Problem Solving and Environmentally Benign Approach toward

Research Article pubs.acs.org/journal/ascecg

Problem Solving and Environmentally Benign Approach toward Diversity Oriented Synthesis of Novel 2‑Amino-3-phenyl (or Alkyl) Sulfonyl‑4H‑chromenes at Ambient Temperature Kapil S. Pandit,† Ravindra V. Kupwade,† Pramod V. Chavan,† Uday V. Desai,*,† Prakash P. Wadgaonkar,‡ and Kisan M. Kodam§ †

Department of Chemistry, Shivaji University, Kolhapur-416004, India Polymer Science and Engineering Division, CSIR, National Chemical Laboratory, Pune-411008, India § Department of Chemistry, Savitribai Phule Pune University Pune, Pune-411008, India

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‡

S Supporting Information *

ABSTRACT: A problem solving, environmentally benign, and diversity oriented protocol has been described for multicomponent synthesis of medicinally privileged 2-amino-3-phenyl (or methyl) sulfonyl-4H-chromenes by one-pot, three component condensation among aldehydes, phenyl (or methyl) sulphonyl acetonitrile, and α-naphthol, 3-dimethylamino phenol, 4-hydroxyN-methyl-quinoline-2-one as well as 4-hydroxycarbazole, using diethylamine as an efficient organo catalyst. The catalyst employed is commercially available, inexpensive, and nontoxic. Ambient reaction conditions, very high yields, wide scope, and avoidance of conventional isolation as well as chromatographic purification have improved the practical utility of this protocol manifold. KEYWORDS: 2-Amino-3-phenylsulfonyl-4H-chromenes, 2-Amino-3-methylsulfonyl-4H-chromenes, Green chemistry, Multicomponent synthesis, Diethylamine, Organocatalyst

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antitumor activities.20−25 They also find applications as cognitive enhancers in the treatment of neodegradable diseases like Alzheimer’s disease, insomnia, etc.26,27 It is a well-established fact that the biological activities of 2-amino-4H-chromenes depend upon the nature of substituents in pyran as well as in adjacent rings. Thus, variation of substituents in both rings result in a large number of structurally related compounds with important biological activities. The structures of a few biologically active 2-amino-4H-chromenes possessing anticancer activities are depicted in Figure 1. A classical approach to the one-pot synthesis of 2-amino-4Hchromenes involves a base catalyzed multicomponent reaction between aldehyde (or isatin) and two different C−H acids.28 In most of the reported protocols, substrates like dimedone, barbituric acid, naphthols, resorcinol, 4-hydroxycoumarin, 4-hydroxyquinolin-2-one, Kojic acid, indane-1,3-dione, 2-hydroxy naphthoquinone, etc. have been used as one of the C−H acids, while the choice of the other C−H acid has been limited toward the use of malononitrile or alkyl cyanoacetate.29−39 More precisely, although many compounds bearing a sulfone moiety are known to possess important applications in the field of

INTRODUCTION Development of enviro-economic protocols for the library synthesis of medicinally promising organic compounds is the aim of current day research. In partial fulfillment of this requirement, use of multicomponent reactions (MCRs) with their welldocumented advantages like high atom economy, reduction in the number of steps, energy consumption, waste production, etc. have become the topic of interest both in academia as well as industries.1−12 Especially, the last two decades have witnessed tremendous developments in multicomponent condensation reactions. The developments have been primarily aimed at the introduction of new multicomponent reactions or toward the development of novel methodologies for known multicomponent reactions. At the same time, multicomponent synthesis of novel and medicinally privileged organic compounds has acquired momentum in recent years.13,14 The chromene moiety often appears as an important structural motif in many naturally occurring compounds with important biological activities.15,16 Among the chromene family members, 2-amino-4H-chromenes, 2-amino-4H-benzo[b]pyrans, constitute an important class of compounds widely used in the field of pigments, cosmetics, and biodegradable agrochemicals.17−19 The interest in this class of compounds has increased in the past few years owing to their wide spectrum of biological activities such as antibacterial, mutageneticidal, antiviral, antihypertensive, and © 2016 American Chemical Society

Received: March 8, 2016 Revised: April 10, 2016 Published: April 13, 2016 3450

DOI: 10.1021/acssuschemeng.6b00484 ACS Sustainable Chem. Eng. 2016, 4, 3450−3464

Research Article

ACS Sustainable Chemistry & Engineering

Figure 1. Representative biologically active 2-amino-4H-chromenes.

Scheme 1. Diversity Oriented Synthesis of 2-Amino-3-phenyl/alkylsulfonyl-4H-chromenes

pharmaceuticals, agrochemicals, polymers, etc.,40there are only a few reports wherein alkyl/arylsulfonyl acetonitrile has been used as the C−H acid in multicomponent synthesis of 2-amino-4Hchromenes.41−43Thus, our attention was focused on the choice of phenylsulfonyl acetonitrile as a C−H acid. The literature survey within the framework of choice of phenyl or alkylsulfonyl acetonitrile in the synthesis of 2-amino4H-chromnes revealed that there exists only a few recent reports on the synthesis of 2-oxo-3-phenylsulfonyl-2H-chromenes (Figure 1F), for the synthesis of spiro-2-amino-3-phenylsulfonyl4H-chromenes (Figure 1G), for the diastereoselective synthesis of [2-amino-3-(phenylsulfonyl)-4H-chromen-4-yl] (phenylsulfonyl)acetonitrile (Figure 1H), etc.44−46 However, to the best of our knowledge, there are no reports on the synthesis of 2-amino-3phenyl/alkylsulfonyl-4-aryl-4H-chromenes. In light of promising anticancer activities associated with 2-amino-3-cyano-4Hchromenes (Figure 1A−E) and the biological activities associated with the compounds containing a sulfonyl group,40 we surmised that the replacement of the cyano functionality in 2-amino-3-cyano4H-chromenes with an alkylsulfonyl or arylsulfonyl group would furnish 2-amino-3-alkylsulfonyl/arylsulfonyl-4-aryl-4H-chromenes,

a novel class of compounds with promising biological activities. With all of these considerations, we planned to undertake the synthesis of 2-amino-3-phenyl/alkylsulfonyl-4H-chromenes. Herein, we describe our studies on the development of a problem solving approach toward the synthesis of 2-amino-3alkyl/phenylsulfonyl-4H-chromenes (Scheme 1). From a mechanistic viewpoint, the synthesis of 2-amino-3phenylsulfonyl-4H-chromenes involves either a two component reaction between 3-aryl-2-(phenylsulfonyl)prop-2-enenitrile, 3, and the requisite C-H acid or a multicomponent reaction among an aldehyde, 1, alkyl/phenylsulfonyl acetonitrile, 2, and a C−H acid, for example, dimedone, 4. The multicomponent reaction follows the Knoevenagel−Michael-cyclocondensation pathway (Scheme 2) and success toward their atom economical synthesis is mainly concerned with the ease of Knoevenagel condensation between an aldehyde and relatively weaker C−H acid viz. alkyl/phenylsulfonyl acetonitrile. A literature survey with regard to Knoevenagel condensation between an aldehyde and alkyl/phenylsulfonyl acetonitrile revealed that there are only a few reports on this condensation reaction47−51and that the reported protocols mainly suffer from 3451


Research Article

ACS Sustainable Chemistry & Engineering Scheme 2. Retrosynthetic Pathway for the Synthesis of 2-Amino-3-aryl/alkyl Sulfonyl-4H-chromenes

the drawbacks with regard to poor yields, elevated temperature, difficulties in the preparation of the catalyst, etc. Hence, we directed our initial efforts toward screening of a base catalyst suitable for Knoevenagel condensation between an aldehyde and phenylsulfonyl acetonitrile. Anisaldehyde, 1a, and phenylsulfonyl acetonitrile, 2a, were selected as two model substrates (Scheme 3).

Table 1. Screening of Catalyst for Knoevenagel Condensation between Anisaldehyde and Phenylsulfonyl Acetonitrilea

Scheme 3. Knoevenagel Condensation between Anisaldehyde and Phenylsulfonyl Acetonitrile

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RESULTS AND DISCUSSION To begin with, a few model reactions were carried out. Thus, an ethanolic solution containing equimolar quantities of anisaldehyde,1a, and phenylsulfonyl acetonitrile, 2a, (1 mmol, each) was stirred together at ambient temperature in the presence of various base catalysts (30 mol %). The reactions were monitored by TLC, and the results are summarized in Table 1. It was noticed that Knoevenagel condensation between anisaldehyde and phenylsulfonyl acetonitrile proceeds equally well in the presence of diethylamine as well as DBU as the catalysts. As compared to DBU as well as various other catalysts reported earlier for this condensation reaction (47−51), use of diethylamine as the catalyst was certainly advantageous from the viewpoint of cost, ease of handling, and ease of removal from the reaction mixture. Similarly, ethanol being a nontoxic and relatively less expensive solvent, studies on optimization of reaction conditions with regard to the choice of other organic solvents were surmised to be unnecessary. Thus, diethylamine− ethanol was selected as the catalyst−solvent combination to establish the generality as well as scope of the protocol. A variety of aromatic aldehydes tethered with electrondonating as well as electron-withdrawing groups were subsequently subjected to condensation with phenylsulfonyl acetonitrile. In all cases, the desired Knoevenagel condensation product resulted in excellent yield (Table 2). However, aliphatic aldehydes like n-butanal as well as cyclohexanecarbaldehyde furnished the desired Knoevenagel condensation product in very poor yield (∼15−20%, TLC) while ketones failed to undergo any reaction under the established reaction conditions.

entry

catalyst (mol %)

time (h)

yield (%)b

1 2 3 4 5 6 7 8 9 9 10 11

K3PO4 (30) K2CO3 (30) MgO (0.5 g) Et3N (30) pyrrolidine (30) piperidine (30) DABCO (30) DBU (30) Et2NH (30) Et2NH (20) Et2NH (15) Et2NH (10)

24 24 24 3 75 60c 60c 25c 3 3 4 8

50 30 20 76 72 82 78 90 89 76 70 50

a

Reaction conditions: anisaldehyde and phenylsulfonyl acetonitrile (1 mmol, each), catalyst, ethanol (5 mL), RT. bIsolated yield. cTime in minutes.

After establishing the generality of the reaction conditions for Knoevenagel condensation between various aromatic or heteroaromatic aldehydes with phenylsulfonyl acetonitrile, we next planned to undertake the synthesis of 2-amino-7,7dimethyl-3-(phenylsulfonyl)-4-methoxyphenyl-4,6,7,8-tetrahydro5H-chromen-5-one, 5, which involves a three component condensation among anisaldehyde, phenylsulfonyl acetonitrile, and dimedone (Scheme 4). In a prototype reaction, a mixture of anisaldehyde, 1a, phenylsulfonyl acetonitrile, 2a, and dimedone, 4 (1 mmol, each), was stirred together in ethanol medium in the presence of diethylamine (30 mol %) as the catalyst (Scheme 4). Upon completion of the reaction (TLC), water (10 mL) was added, and the resulting mass was extracted using ethyl acetate. Routine workup followed by chromatographic separation indicated the formation of three major products viz. Knoevenagel condensation product, 3 (20%), the desired product, 5 (10%), and tetraketone, 6 (35%). The formation of tetraketone at a high amount was a little surprising for us, and it was concluded that in diethylamine catalyzed reaction of anisaldehyde with two different C−H acids, compared to phenylsulfonyl acetonitrile 3452


Research Article

ACS Sustainable Chemistry & Engineering Table 2. Diethylamine Catalyzed Condensation between Aldehydes and Phenylsulfonyl Acetonitrilea

melting point (0C)ref entry

aldehyde (1)

time (h)

yield (%)

3a 3b 3c 3d 3e 3f 3g 3h 3i 3j 3k 3l 3m

benzaldehyde 4-methoxybenzaldehyde 4-methylbenzaldehyde 4-chlorobenzaldehyde 3,4- dimethoxybenzaldehyde 4-cyanobenzaldehyde 4 - Bromobenzaldehyde 3-nitrobenzaldehyde piperonal thiophen-2-carbaldehyde 4-hydroxy benzaldehyde n-butyraldehyde cyclohexanecarbaldehyde

1.5 1.5 1.5 1.5 1.5 1.0 1.5 1.0 1.0 1.5 1.5 8 8

93 70 92 80 95 82 89 85 92 87 91 traces traces

b

Obs.

Lit.

135−139 110−112 148−151 156−158 152−155 189−192 146−148 150−152 172−175 114−115 218−221

130−13276 113−11578 144−14679 152−15479

15277 170−17277

a Reaction conditions: anisaldehyde and phenylsulfonyl acetonitrile (1 mmol, each), diethylamine (30 mol %), ethanol (5 mL), RT. bIsolated product; NR, no reaction.

Scheme 4. Attempted Synthesis of 2-Amino-3-phenylsulfonyl Tetrahydrobenzo[b]pyran, 5

Scheme 5. Attempted Synthesis of Pyrano [3,2-c]chromen-5-one, 8

condensation product, 3 (15%), bis-coumarin, 9 (25%), and desired product, 8 (30%). This interesting result once again prompted us to conclude that this diethylamine catalyzed multicomponent reaction preferentially follows the Knoevenagelcarba-Michael-domino reaction pathway to furnish bis-coumarin as another undesirable reaction product. At the same time, formation of the desired product, 8, in improved yield by change in the third component from dimedone (Scheme 4) to 4-hydroxycoumarin (Scheme 5) indirectly projected that with the choice of another C−H acid with still lower acidity, the reaction course can be directed to follow exclusively the Knoevenagelcarba-Michael-Pinner cyclization pathway to obtain targeted 2-amino-3-phenylsulponyl-4H-chromenes, in acceptable yield. It is well-known that the similar 1,3-diketones, phenols, naphthols as well as resorcinols do serve as enolizable C−H acids. Thus, we became interested in replacing the 4-hydroxycoumarin component of the model reaction by α-naphthol (pKa = 9.31). A literature survey revealed that there is only one earlier report

(pKa = 12) dimedone being more acidic (pKa = 5.23), diethylamine not only promotes Knoevenagel condensation between aldehyde and dimedone but also promotes the subsequent carba-Michael-domino reaction to furnish tetraketone, 6, as the major, but undesired, product (Scheme 4). To give credence to this observation, we next planned to replace the dimedone component from the above model reaction by another 1,3-diketone viz. 4-hydroxycoumarin, 7. It was surmised that 4-hydroxycoumarin being weaker in acidity (pKa = 7.79) than dimedone, a three component reaction between an aldehyde, 4-hydroxycoumarin, and phenylsulfonyl acetonitrile would furnish pyrano [3,2-c]chromen-5-one, 8 (Scheme 5). Accordingly, a reaction was performed using anisaldehyde, 1a, phenylsulfonyl acetonitrile, 2a, and, 4-hydroxycoumarin, 7, as the substrates and diethylamine (30 mol %) as the catalyst (Scheme 5). Upon completion of the reaction (TLC) followed by workup as well as chromatographic separation, we once again observed the formation of three main products viz. Knoevenagel 3453


Research Article

ACS Sustainable Chemistry & Engineering Scheme 6. Synthesis of Benzo[h]chromen-2-amine, 11/12

involving a multicomponent condensation among aldehydes, phenylsulfonyl acetonitrile, and α-naphthol and that the synthesized compounds were shown to possess important biological properties.52 This particular report encouraged us to screen the catalytic potential of diethylamine in three component condensation among anisaldehyde, phenylsulfonyl acetonitrile, and α-naphthol (Scheme 6). Once again, a model reaction was carried out using anisaldehyde, 1a, phenylsulfonylacetonitrile, 2a, and α-naphthol, 10, as the substrates (1 mmol, each) and diethylamine (30 mol %) as the catalyst (Scheme 6). Upon completion of the reaction (TLC), the reaction mixture was treated with water, and the resultant solid was filtered, washed with water, and dried. TLC examination of the resultant product indicated the presence of phenylsulfonyl acetonitrile only in traces. The resultant solid on simple washing with hexane−chloroform mixture (3 × 10 mL, 3:1, v/v) furnished the pure product. Its spectral analysis indicated the same to be the desired product viz. 4-(4methoxyphenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen-2amine, 11a. The reaction conditions established for the synthesis of 11a were very close to those defined for an ideal synthesis, and further optimization of the reaction conditions was surmised unnecessary. So as to examine the scope of the developed protocol, the phenylsulphonyl acetonitrile component from the model reaction was replaced with methylsulfonyl acetonitrile, 2b. Most gratifyingly, under the same reaction conditions, the corresponding chromene derivative viz. 4-(4-methoxyphenyl)-3(methylsulfonyl)-4H-benzo[h]chromen-2-amine, 12a, was obtained in acceptable yield. So as to establish the generality of the reaction conditions, various aromatic aldehydes bearing electronwithdrawing as well as electron-donating groups were allowed to react with α-naphthol and phenylsulfonyl as well as methylsulfonyl acetonitrile. In all the cases, corresponding 2-amino-3phenylsulphonyl-4H-chromenes, 11b−h and 12b−d, were obtained in acceptable yield (Table 3). After this initial success, our attention was focused on resorcinol as the possible C−H acid. This is because it has earlier been demonstrated that 2-amino-7-(dimethylamino)-4aryl-4H-chromene-3-carbonitriles (Figure 1E) resulting by one-pot, three component condensation among aldehydes, malononitrile, and 3-dimethylaminophenol are known to possess anticancer as well as apoptosis inducer activities.53−56 However, to the best of our knowledge, there are no reports on the synthesis and consequently on the biological activities of 2-amino-7(dimethylamino)-4-aryl-3-phenylsulphonyl-4H-chromenes, 14. Thus, we planned to extend the scope of the developed protocol toward the synthesis of 14 (Scheme 7). In a model reaction anisaldehyde, 1a, phenylsulphonyl acetonitrile, 2a, and 3-dimethylaminophenol, 13, were allowed to react under the reaction conditions established for the synthesis of 11 (Scheme 7). During monitoring of the reaction, TLC examination indicated the formation of the desired product, 14a, as a major product. However, the reaction did not go to

completion. Modification of the reaction conditions with regard to the increase in the amount of the catalyst, reaction temperature, and the change in solvent were not found to be useful in driving the reaction to completion. Hence, the resultant solid was filtered and taking recourse to the solubility behavior of 14a, a nonconventional way was adopted for it is purification. The filtered solid was allowed to dry in air, washed with a hexane− chloroform mixture (3 × 10 mL, 3:1, v/v), and dried again. The resultant solid product did not require any further purification and was identified to be the desired product, 14a. So as to examine generality of the reaction conditions, various aromatic aldehydes bearing electron-withdrawing as well as electrondonating groups were allowed to react with dimethylamino phenol and phenylsulfonyl or methylsulfonyl acetonitrile. In all of the cases, corresponding 2-amino-3-phenyl-sulphonyl-4Hchromenes, 14b−h and 15a−d, were obtained in acceptable yield (Table 3). All of the synthesized compounds being new compounds, their structures were fully established by various spectral methods. This initial success prompted us to develop a diversity oriented protocol for the synthesis of various 2-amino3-phenyl (or methyl) sulphonyl-4H-chromenes with established biological activities. It is well-known that the pyranoquinolone moiety is a structural feature of many naturally occurring bioactive alkaloids like smulenoline, huajiosimuline, findersine, etc. In recent years, the derivatives of pyranoquinolones have attracted much attention because of their important biological activities mainly the antiinflammatory as well as antiallergic activities.57−64 They also bear pharmacological activities such as anticoagulant, coronary constructing, antifungal, and cancer cell growth inhibitory activity. Despite these facts, only a limited number of protocols have been reported for their synthesis.65−68 For instance, Elinson et al. have reported the synthesis of 2-amino-3-cyano pyrano(3,2-c)quinolones by a three component condensation among an aldehyde, malononitrile, and 4-hydroxy-N-methyl quinolone,69 while their synthesis using Tris-hydroxymenthylaminomethane (THAM) as an organo catalyst has recently been reported by us.28However, to the best of our knowledge, there are no reports on the synthesis of pyrano (3,2-c) quinolones containing an alkyl/arylsulfonyl group. Alike pyrano [3,2-c] quinolones, compounds containing carbazole as the structural motif, are also known to exhibit a very wide of range of biological activities such as antitumor, antiinflammatory, antitubercular, psychotropic, and antihistaminic properties.70−73 Among carbazole derivatives, compounds like girinimbine as well as isomahanine (Figure 2A and B) are known to possess excellent cytotoxic activities. Quite recently, the synthesis of pyrano [3,2-c] carbazoles containing a nitrile function at position three has been reported by Padmaja et al. following one-pot, three component condensation among aldehydes, malononitrile, and 4-hydroxycarbazole and the resultant pyrano[3,2-c]carbazoles were shown to possess excellent antitumor activities.74 With reference to our earlier contribution 3454


Research Article

ACS Sustainable Chemistry & Engineering Table 3. Diethylamine Catalyzed Syntheses of 2-Amino-4H-chromenes, 11-12/14-15a

time

yield

entry

aldehyde (1)

product

(h)

(%)

melting point (°C)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

4-methoxybenzaldehyde 4-methoxybenzaldehyde 4-isopropylbenzaldehyde 4-isopropylbenzaldehyde 3-nitrobenzaldehyde 3-nitrobenzaldehyde 4-bromobenzaldehyde 4-bromobenzaldehyde thiophene-2-carbaldehyde thiophene-2-carbaldehyde 4-cyanobenzaldehyde 4-cyanobenzaldehyde benzaldehyde benzaldehyde 4-methoxybenzaldehyde 4-methoxybenzaldehyde 3-nitrobenzaldehyde 3-nitrobenzaldehyde piperonal 4-isopropylbenzaldehyde 3,4,5-trimethoybenzaldehyde 4-chlorobenzaldehyde 2,5-dimethoxybenzaldehyde 4-methylbenzaldehyde benzaldehyde

11a 14a 11b 14b 11c 14c 11d 14d 11e 14e 11f 14f 11g 14g 12a 15a 12b 15b 12c 15c 11h 14h 14i 14j 12d

4.0 5.0 4.5 5.0 3.5 4.5 4 5 4.5 5.5 3.5 4 4 5 4.5 5.5 4 5 4 6 4 5 5.5 5 5

91 91 90 90 93 93 92 92 89 86 93 94 85 92 83 81 87 85 86 78 88 90 84 90 81

156−158 202−205 225−228 168−170 275−278 222−225 254−257 208−211 258−261 179−181 251−254 187−189 248−251 156−159 175−178 163−165 184−187 185−187 205−208 156−158 222−225 184−187 228−231 159−162 158−161

a Reaction conditions: aldehyde, phenylsulfonyl acetonitrile/methylsulfonyl acetonitrile, and α-naphthol or 3-dimethylaminophenol (1 mmol, each), DEA (30 mol %), ethanol (5 mL), RT.

Scheme 7. Synthesis of 2-Amino-7-(dimethylamino)-4-aryl-3-phenyl (or Methyl) Sulphonyl-4H-chromenes

toward the synthesis of pyrano [3,2-c] carbazoles,75 it was quite logical for us to test the catalytic potential of diethylamine in the synthesis of pyrano[3,2-c] carbazoles containing an alkyl/ arylsulphonyl acetonitrile group at position 3 (Figure 2D). To the best of our knowledge, there are no reports on the synthesis of title compounds.Thus, we planned to explore the potential of diethylamine as the catalyst in the synthesis of pyrano[3,2-c]quinolin-5-ones, 17/18, as well as pyrano [3,2-c] carbazoles, 20/21 (Scheme 8). Initially, two model reactions were carried out using anisaldehyde, phenylsulfonyl acetonitrile, and 4-hydroxy-N-methylquinolone,

16, or 4-hydroxycarbazole, 19, as the substrates employing the reaction conditions established for the synthesis of 11 (Scheme 8). With the progress of the reaction, the formation of free-flowing solid was noticed and upon completion of the reaction (TLC) followed by workup as described earlier. The resultant solids were identified to be the desired pyrano[3,2-c]quinolone, 17a, and pyrano [3,2-c] carbazole, 20a, respectively. So as to examine the scope of the protocol and generality of the reaction conditions, various aromatic and heteroaromatic aldehydes were allowed to react with N-methyl-4-hydroxy quinolone and 4-hydroxycarbazole using phenylsulfonyl as well 3455


Research Article


quinoline-2-one was received as a gift sample from M/S Bravil Chemicals, Kolhapur, India. Melting points were recorded using a Kumar melting point apparatus. IR spectra were recorded using a PerkinElmer Spectrum 1 spectrometer. 1H and 13C NMR spectra were recorded using a Bruker Avance-II (300 MHz) spectrometer. High resolution mass spectra (HRMS) were recorded using a ThermoScientific-Q-Exactive, Accela 1250 pump, instrument. Representative Experimental Procedure for the Synthesis of 3. To a well stirred solution of substituted benzaldehyde, 1, and phenylsulphonyl acetonitrile, 2a (1 mmol, each), in ethanol (5 mL) was added diethylamine (30 mol %), and stirring was continued. Upon completion of the reaction (TLC), water (15 mL) was added, and the resultant solid was filtered, dried, and washed with hexane−chloroform mixture (3 × 10 mL, 3:1, v/v) and dried again. The resultant product 3 was found to be pure and did not require any further purification. General Experimental Procedure for the Synthesis of 11, 12/14, 15/17, 18/20, and 21. To a well stirred solution of substituted aldehyde, 1 (1 mmol), phenylsulphonyl acetonitrile 2a, or methylsulfonyl acetonitrile, 2b (1 mmol), and α-naphthol, 10, or 3-dimethylaminophenol, 13, or 4-hydroxy-N-methyl-quinolone, 16, or 4-hydroxycarbazole, 19 (1 mmol, each) in ethanol (5 mL) was added diethylamine (30 mol %) and stirring was continued at ambient temperature. Upon completion of the reaction (TLC), water (15 mL) was added, and the resultant solid was filtered, dried, and washed with hexane−chloroform mixture (3 × 10 mL, 3:1, v/v) and dried again. The resultant products, 11, 12/14, 15/17, 18/20, and 21, were found to be pure and did not require any further purification. Spectral Data of the New Compounds. 3-Phenyl-2(phenylsulfonyl)prop-2-enenitrile, 3a. Solid. M. P.: 135−139 °C. IR (KBr): 3083, 2885, 2215, 1669, 1467, 757 cm−1. 1H NMR (300 MHz, CDCl3): δ 7.50 (t, 2H, J = 7.0 and 7.8 Hz), 7.57 (d, 1H, J = 7.1 Hz), 7.62 (t, 2H, J = 7.1 and 7.9 Hz), 7.72 (t, 1H, J = 7.4 and 7.5 Hz), 7.93 (d, 2H, J = 7.5 Hz), 8.0 (d, 2H, J = 7.5), 8.2 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 113.11, 114.7, 128.7, 129.5, 129.7, 130.1, 131.0, 134.2, 134.7, 137.8, 151.6 ppm. 3-(4-Methoxyphenyl)-2-(phenylsulfonyl)prop-2-enenitrile, 3b. Solid. M. P.: 110−112 °C. IR (KBr): 3122, 2922, 2222, 1567, 1512, 857 cm−1. 1H NMR (300 MHz, CDCl3): δ 3.9 (s, 3H), 6.9 (d, 2H, J = 8.9 Hz), 7.61 (m, 2H), 7.68 (m, 1H), 7.92 (d, 2H, J = 8.9 Hz), 8.0 (d, 2H, J = 8.4 Hz), 8.1 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 55.73, 110.90, 113.76, 115.02, 122.96, 128.47, 129.60, 133.68, 134.35, 138.50, 150.99, 164.51 ppm. 3-(4-Methylphenyl)-2-(phenylsulfonyl)prop-2-enenitrile, 3c. Solid. M. P.: 148−151 °C. IR (KBr): 3126, 3022, 2971, 2238, 1567, 1540, 757 cm−1. 1H NMR (300 MHz, CDCl3): δ 2.44 (s, 3H), 7.27 (t, 2H, J = 7.6 and 8.1 Hz), 7.60−7.71 (m, 3H), 7.82 (d, 2H, J = 8.1 Hz), 8.0 (d, 2H, J = 8.1 Hz), 8.14 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 21.95, 113.24, 113.37, 127.56, 128.61, 129.65, 130.27, 131.22, 134.53, 138.15, 145.75, 151.54 ppm.

Figure 2. Structures of pyrano (3,2-c) carbazoles.

as methylsulfonyl acetonitrile as the C−H acids. In all of the cases, corresponding pyrano (3,2-c)quinolones 17b−h, 18a−c, and pyrano [3,2-c] carbazoles, 20b−h and 21a−d, were obtained in excellent yield as well as purity (Table 4).

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CONCLUSIONS A plethora of methods have earlier been reported for the synthesis of 2-amino-3-cyano-4H-chromenes. However, reports on the synthesis of 2-amino-3-aryl (or alkyl) sulphonyl-4Hchromenes are scanty. This observation made us uncover the reason behind not selecting arylsulphonyl or alkylsulphonyl acetonitrile in the multicomponent synthesis of 2-amino-4Hchromenes. In this article, we have not only uncovered the reason behind the same but also have successfully developed an enviro-economic protocol for the synthesis of 2-amino-3-aryl (or alkyl) sulphonyl-4H-chromenes using diethylamine as a commercially available, inexpensive, and easy to handle catalyst. A wide scope, ambient reaction conditions, and avoidance of chromatographic purification are the noteworthy features of the developed protocol. Perhaps this is the simplest and most ecofriendly protocol designed for the synthesis of targeted compounds.

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EXPERIMENTAL SECTION

General. All aldehydes, 3-dimethylaminophenol, phenylsulphonyl acetonitrile, methylsulfonyl acetonitrile, and 4-hydroxy coumarin (Aldrich), dimedone (SD fine chemicals, Mumbai), and 4-hydroxy carbazole (Spectrochem, Mumbai) were used as received. N-Methyl

Scheme 8. Synthesis of Pyrano [3, 2-c]Quinolin-5-ones and Pyrano [3,2-c] Carbazoles

3456


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ACS Sustainable Chemistry & Engineering Table 4. Diethylamine Catalyzed Synthesis of 2-Amino-4H-chromenes, 17, 18, 20, and 21a

time

yield

entry

aldehyde (1)

product

(h)

(%)

melting point (°C)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

4-methoxybenzaldehyde 4-methylbenzaldehyde 3-nitrobenzaldehyde 4-bromobenzaldehyde 4-chlorobenzaldehyde benzaldehyde 4-cyanobenzaldehyde 4-allyoxybenzaldehyde 3,4-dimethoxybenzaldehyde 4-isopropylbenzaldehyde thiophene-2-carbaldehyde 3-nitrobenzaldehyde 4-methoxybenzaldehyde 3-methylthiophene-2-carbaldehyde 4-methoxybenzaldehyde 4-bromobenzaldehyde 4-allyloxybezaldehyde 4-cyanobenzaldehyde 2,5-dimethylbenzaldehyde 3,4-dimethoxybenzaldehyde 3,4,5-trimethoxybenzaldehyde 6-nitropiperonal thiophene-2-carbaldehyde 5-methylfurfural 3-nitrobenzaldehyde 4-isopropylbenzaldehyde

17a 17b 17c 17d 17e 17f 17g 17h 17i 17j 17k 18a 18b 18c 20a 20b 20c 20d 20e 20f 20g 20h 21a 21b 21c 21d

5 5 4.5 5 5 5 4 5.5 5.5 5 5.5 5 5.5 6 5 5 5.5 4.5 5.5 5 5 4.5 5 5.5 5.5 6

91 90 93 92 91 92 94 87 84 90 86 85 81 78 87 86 84 89 84 85 87 89 83 80 84 81

199−201 167−170 188−190 223−225 204−207 218−222 206−208 218−220 138−141 178−181 189−192 192−195 195−198 215−218 165−167 228−231 218−221 206−208 238−240 202−205 218−221 212−215 198−201 207−210 162−165 145−148

a

Reaction conditions: aldehyde, phenylsulphonyl/methylsulfonyl acetonitrile, and 4-hydroxy-N-methylquinolone/4-hydroxycarbazole (1 mmol, each), DEA (30 mol %), ethanol (5 mL), RT.

3-(4-Chlorophenyl)-2-(phenylsulfonyl)prop-2-enenitrile, 3d. Solid. M. P.: 156−158 °C. IR (KBr): 3111, 3082, 3018, 2231, 1587, 1398, 797 cm−1. 1H NMR (300 MHz, CDCl3): δ 7.49 (d, 2H, J = 8.6 Hz), 7.63 (t, 2H, J = 7 and 7.8 Hz), 7.70−7.76 (m, 1H), 7.88 (d, 2H, J = 8.6 Hz), 8.0 (d, 2H, J = 8.5 Hz), 8.15 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 112.92, 115.25, 128.57, 128.75, 129.75, 129.93, 132.15, 134.79, 137.67, 140.55, 149.89 ppm. 3-(4-Cyanophenyl)-2-(phenylsulfonyl)prop-2-enenitrile, 3f. Solid. M. P.: 189−192 °C. IR (KBr): 3145, 3034, 2971, 2208, 1581, 1431, 857 cm−1. 1H NMR (300 MHz, CDCl3): δ 7.65 (t, 2H, J = 7.1 and 7.9 Hz), 7.75−7.81 (m, 3H), 8.02 (d, 2H, J = 6 Hz), 8.04 (d, 2H, J = 5.4 Hz), 8.2 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 99.98, 112.13, 117, 119.08, 129.02, 129.72, 131, 132.84, 134, 135, 137.32, 148.43 ppm. 3-(4-Bromophenyl)-2-(phenylsulfonyl)prop-2-enenitrile,3g. Solid. M. P.: 146−148 °C. IR (KBr): 3098, 3034, 2993, 2227, 1621, 1439, 973 cm−1. 1H - NMR (300 MHz, CDCl3): δ 7.61−7.67 (m, 4H), 7.71−7.76 (m, 1H), 7.80 (d, 2H, J = 8.6 Hz), 8.1 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 12.92, 115.37, 128.75, 128.97, 129.27, 129.77, 132.16, 132.93, 134.81, 137.62, 150.01 ppm. 3-(3-Nitrophenyl)-2-(phenylsulfonyl)prop-2-enenitrile, 3h. Solid. M. P.: 150−152 °C. IR (KBr): 3118, 3028, 2981, 2208, 1385, 1212, 829 cm−1. 1H NMR (300 MHz, CDCl3): δ 7.64−7.79 (m, 4H), 8.04

(d, 2H, J = 7.5 Hz), 8.3 (s, 1H), 8.35 (d, 1H, J = 8.0 Hz), 8.42 (d, 1H, J = 8.1 Hz), 8.67 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 112.32, 118.44, 125.85, 127.77, 128.93,129.92, 130.79, 131.61, 135.16, 137.05, 148.38, 148.64 ppm. 3-(1,3-Benzodioxol-5-yl)-2-(phenylsulfonyl)prop-2-enenitrile, 3i. Solid. M. P.: 172−175 °C. IR (KBr): 3144, 3051, 2981, 2219, 1591, 1318, 932 cm−1. 1H NMR (300 MHz, CDCl3): δ 6.12 (s, 2H), 6.93 (d, 1H, J = 8.1 Hz), 7.40 (d, 1H, J = 8.2 Hz), 7.62 (m, 3H), 7.7 (m, 1H), 8.05 (d, 2H, J = 7.6 Hz), 8.1 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 102.5, 108.6, 109.1, 113.5, 117.4, 124.6, 128.5, 129.6, 130.1, 134.5, 138.3, 148.9, 150.9, 153.0 ppm. (Phenylsulfonyl)-3-(thiophen-2-yl)prop-2-enenitrile, 3j. Solid: M. P.: 114−115 °C. IR (KBr): 3189, 3092, 3022 2224, 1589, 1390, 919 cm−1. 1H NMR (300 MHz, CDCl3): δ 7.25 (t, 1H, J = 4.6 and 4.4 Hz), 7.63 (m, 2H), 7.73 (m, 1H), 7.83 (d, 2H, J = 4.5 Hz), 8.0 (d, 2H, J = 7.4 Hz), 8.4 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 111.5, 113.0, 128.5, 128.8, 129.5, 134.3, 134.6, 135.6, 137.3, 138.6, 143.0 ppm. 4-(4-Methoxyphenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen-2amine, 11a: Off-white solid. M. P.: 156−158 °C. IR (KBr): 3442, 3092, 2955, 1632, 1521, 1321, 729 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.64 (s, 3H), 4.97 (s, 1H), 6.68 (d, 2H, J = 9.1 Hz), 7.09 (d, 2H, J = 8.4 Hz), 7.30 (d, 1H, J = 8.7 Hz), 7.37 (d, 2H, J = 7.4 Hz), 7.40 (s, 2H), 7.48 (t, 2H, J = 8.2 Hz), 7.55−7.62 (m, 3H), 7.69 (d, 2H, J = 6.7 Hz), 7.84 (d, 1H, J = 7.3 Hz). 13C NMR (75 MHz, 3457


Research Article

ACS Sustainable Chemistry & Engineering DMSO-d6): δ 40.69, 55.47, 83.27, 114.16, 121.21, 121.98, 123.16, 124.47, 126.40, 127.00, 127.04, 128.07, 128.67, 129.18, 132.52, 132.88, 138.34, 142.93, 144.29, 158.23, 158.57 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Isopropylphenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen2-amine, 11b: Off-white solid. M.P.: 225−228 °C. IR (KBr): 3440, 3318, 3109, 3056, 1621, 1372, 719 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 1.07 (d, 3H, J = 2.4 Hz), 1.10 (d, 3H, J = 2.4 Hz), 2.67− 2.76 (m, 1H), 5.00 (s, 1H), 6.96 (d, 2H, J = 8.3 Hz), 7.08 (d, 2H, J = 8.2 Hz), 7.30 (d, 1H, J = 3.7 Hz), 7.34 (t, 2H, J = 7.8 Hz), 7.43 (s, 2H), 7.48 (t, 1H, J = 7.3 Hz), 7.55 (t, 2H, J = 9.4 Hz), 7.60 (t, 1H, J = 6.9 Hz), 7.66 (t, 2H, J = 7.5 Hz), 7.84 (d, 1H, J = 8.00 Hz), 8.28 (d, 1H, J = 8.2 Hz). 13C NMR (75 MHz, DMSO-d6): δ 24.27, 24.33, 33.46, 41.17, 83.14, 121.23, 121.85, 123.17, 124.52, 126.16, 126.65, 127.03, 127.05, 127.53, 128.07, 129.12, 132.49, 132.91, 142.99, 143.43, 144.24, 146.79, 158.65 ppm. HRMS: mass calculated for [C28H25NO3S], 456.1633 [M + H]+ and 478.1453 [M + Na]+; obs. mass 456.1627 [M + H]+ and 478.1447 [M + Na]+. 4-(3-Nitrophenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen-2amine, 11c. Pale yellow solid. M.P.: 275−278 °C. IR (KBr): 3441, 3087, 2966, 1653, 1511, 1322, 819 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.31 (s, 1H), 7.33−7.39 (m, 3H), 7.42 (s, 1H), 7.46 (d, 1H, J = 7.8 Hz), 7.52−7.57 (m, 1H), 7.59 (s, 1H), 7.62 (s, 1H), 7.64 (s, 2H), 7.71 (s, 2H), 7.73 (s, 1H), 7.85 (d, 1H, J = 8.0 Hz), 7.90 (t, 1H, J = 9.5 Hz), 7.95 (t, 1H, J = 2.6 Hz), 8.31 (d, 1H, J = 8.3 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 40.82, 82.04, 120.34, 121.34, 121.90, 122.16, 123.11, 124.86, 126.08, 127.26, 127.38, 128.13, 129.29, 130.47, 132.68, 133.16, 134.56, 143.13, 144.09, 148.09, 148.15, 158.87 ppm. HRMS: mass calculated for [C25H18N2O5S], 459.1014 [M + H]+ and 481.0834 [M + Na]+; obs. mass 459.1011 [M + H]+ and 481.0832 [M + Na]+. 4-(4-Bromophenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen-2amine, 11d. Solid. M.P.: 254−257 °C. IR (KBr): 3481, 3092, 2909, 1671, 1555, 1172, 829 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.04 (s, 1H), 7.16 (d, 2H, J = 8.4 Hz), 7.30 (d, 1H, J = 1.8 Hz), 7.32 (d, 1H, J = 2.0 Hz), 7.40 (t, 2H, J = 7.7 Hz), 7.48−7.53 (m, 4H), 7.55−7.58 (m, 2H), 7.60 (t, 1H, J = 7.1 Hz), 7.73 (d, 2H, J = 7.6 Hz), 7.84 (d, 1H, J = 8.0 Hz), 8.28 (d, 1H, J = 8.3 Hz). 13C NMR (75 MHz, DMSO-d6): δ 40.74, 82.63, 119.91, 121.01, 121.27, 123.14, 124.65, 126.15, 126.21, 127.15, 127.19, 128.10, 129.29, 129.91, 131.61, 132.64, 133.03, 143.03, 144.13, 145.71, 158.69 ppm. HRMS: mass calculated for [C25H18BrNO3S], 492.0268 [M + H]+ and 514.0089 [M + Na]+; obs. mass 492.0261 [M + H]+ and 514.0075 [M + Na]+. 3-(Phenylsulfonyl)-4-(thiophen-2-yl)-4H-benzo[h]chromen-2amine,11e. Solid. M. P.: 258−261 °C. IR (KBr): 3466, 2918, 1609, 1510, 1221, 1172, 929 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.40 (s, 1H), 6.78 (dd, 1H, J = 8.4 and 3.9 Hz), 6.94 (d, 1H, J = 3.2 Hz), 7.17 (d, 1H, J = 4.8 Hz), 7.42 (d, 1H, J = 7.0 Hz), 7.45 (s, 1H), 7.48 (s, 3H), 7.54 (t, 2H, J = 9.8 Hz), 7.63 (t, 2H, J = 8.7 Hz), 7.80 (d, 2H, J = 7.5 Hz), 7.88 (d, 1H, J = 7.8 Hz), 8.26 (d, 1H, J = 8.0 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 36.70, 83.62, 121.23, 121.71, 123.12, 124.27, 124.68, 125.16, 126.14, 126.17, 127.04, 127.15, 127.19, 128.14, 129.32, 132.69, 133.12, 143.34, 144.33, 151.37, 158.90 ppm. HRMS: mass calculated for [C13H12N4O2], 420.0728 [M + H]+ and 442.0548 [M + Na]+; obs. mass 420.0723 [M + H]+ and 442.0540 [M + Na]+. 4-(2-Amino-3-(phenylsulfonyl)-4H-benzo[h]chromen-4-yl)benzonitrile, 11f. Solid. M. P.: 251−254 °C. IR (KBr): 3491, 3023, 2908, 1656, 1521, 1122, 817 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.17 (s, 1H), 7.34 (d, 1H, J = 8.5 Hz), 7.40 (d, 1H, J = 4.4 Hz), 7.41 (s, 1H), 7.43 (s, 2H), 7.52 (t, 2H, J = 7.3 Hz), 7.59 (s, 4H), 7.61 (d, 2H, J = 7.3 Hz), 7.74 (d, 2H, J = 7.8 Hz), 7.85 (d, 1H, J = 8.0 Hz), 8.28 (d, 1H, J = 8.2 Hz). 13C NMR (75 MHz, DMSO-d6): δ 41.35, 82.10, 109.59, 119.22, 120.38, 121.30, 123.12, 124.79, 126.09, 126.16, 127.24, 127.35, 128.12, 128.71, 129.36, 132.79, 132.83, 133.14, 143.16, 143.99, 151.71, 158.82 ppm. HRMS: mass calculated for [C26H18N2O3S], 439.1116 [M + H]+ and 461.0936 [M + Na]+; obs. mass 439.1114 [M + H]+ and 461.0935 [M + Na]+.

4-Phenyl-3-(phenylsulfonyl)-4H-benzo[h]chromen-2-amine, 11g. Solid. M. P.: 248−251 °C. IR (KBr): 3448, 3055, 2987, 1628, 1542, 1162, 949 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.04 (s, 1H), 7.05 (t, 1H, J = 7.1 Hz), 7.12 (t, 2H, J = 7.4 Hz), 7.21 (d, 2H, J = 7.3 Hz), 7.35 (t, 2H, J = 8.4 Hz), 7.40 (s, 1H), 7.46 (s, 2H), 7.48 (s, 1H), 7.51 (d, 1H, J = 6.7 Hz), 7.56 (t, 1H, J = 4.7 Hz), 7.60 (t, 1H, J = 6.9 Hz), 7.71 (d, 2H, J = 7.4 Hz), 7.84 (d, 1H, J = 8.2 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 41.52, 82.98, 121.25, 121.79, 123.17, 124.55, 126.16, 126.34, 126.76, 127.08, 127.60, 128.08, 128.78, 129.23, 132.60, 132.94, 143.06, 144.18, 146.18, 158.78 ppm. HRMS: mass calculated for [C25H19NO3S], 414.1164 [M + H]+ and 436.0984 [M + Na]+; obs. mass 414.1162 [M + H]+and 436.0981 [M + Na]+. 4-(3,4,5-Trimethoxyphenyl)-3-(phenylsulfonyl)-4H-benzo[h]chromen-2-amine, 11h. Solid. M.P.: 222−225 °C. IR (KBr): 3476, 3088, 2965, 1671, 1531, 1172, 779 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.53 (s, 3H), 3.56 (s, 6H), 5.04 (s, 1H), 6.39 (s, 2H), 7.34 (t, 2H, J = 7.6 Hz), 7.43 (d, 1H, J = 8.7 Hz), 7.51 (s, 2H), 7.54 (d, 1H, J = 7.1 Hz), 7.59 (d, 2H, J = 8.9 Hz), 7.63 (d, 2H, J = 7.9 Hz), 7.86 (d, 1H, J = 7.9 Hz), 8.28 (d, 1H, J = 8.1 Hz). 13C NMR (75 MHz, DMSO-d6): δ 41.69, 56.06, 60.24, 82.47, 104.92, 121.21, 121.32, 123.11, 124.43, 126.29, 126.36, 127.05, 128.08, 128.91, 132.47, 132.96, 136.41, 140.85, 142.75, 144.36, 153.05, 158.63 ppm. HRMS: mass calculated for [C13H12N4O2], 257.1039 [M + H]+ and 279.0858 [M + Na]+; obs. mass 257.1025 [M + H]+ and 279.0852 [M + Na]+. 4-(4-Methoxyphenyl)-3-(methylsulfonyl)-4H-benzo[h]chromen2-amine,12a. Solid. M. P.: 175−178 °C. IR (KBr): 3475, 3011, 3964, 1655, 1543, 1312, 759 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.68 (s, 3H), 5.00 (s, 1H), 5.94 (d, 2H, J = 7.4 Hz), 6.80 (s, 2H), 6.83 (s, 1H), 7.13 (s, 2H), 7.36 (d, 1H, J = 8.5 Hz), 7.56 (t, 1H, J = 7.7 Hz), 7.64 (t, 2H, J = 8.4 Hz), 7.89 (d, 1H, J = 7.7 Hz), 8.30 (d, 1H, J = 8.1 Hz). 13C NMR (75 MHz, DMSO-d6): δ 40.93, 43.79, 83.42, 101.39, 108.13, 108.72, 120.84, 121.27, 121.62, 123.22, 124.45, 126.52, 127.06, 128.12, 132.99, 140.60, 143.08, 146.38, 147.86, 158.05 ppm. HRMS: mass calculated for [C21H19NO4S], 382.1113 [M + H]+ and 404.0933 [M + Na]+; obs. mass 382.1108 [M + H]+ and 404.0928 [M + Na]+. 3-(Methylsulfonyl)-4-(3-nitrophenyl)-4H-benzo[h]chromen-2amine, 12b. Solid. M. P.: 184−187 °C; IR (KBr): 3490, 3018, 2909, 1686, 1599, 1172, 812 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.83 (s, 3H), 5.34 (s, 1H), 7.28 (s, 2H), 7.43 (d, 1H, J = 8.6 Hz), 7.55−7.60 (m, 2H), 7.63 (d, 1H, J = 3.8 Hz), 7.66 (d, 1H, J = 5.0 Hz), 7.78 (d, 1H, J = 8.1 Hz), 7.90 (d, 1H, J = 7.7 Hz), 8.04 (dd, 1H, J = 1.6 and 8.0 Hz), 8.18 (t, 1H, J = 2.0 Hz), 8.34 (d, 1H, J = 8.1 Hz). 13C NMR (75 MHz, DMSO-d6): δ 40.21, 42.94, 82.14, 120.17, 120.85, 121.65, 121.68, 122.73, 124.28, 125.86, 126.74, 126.85, 127.67, 130.23, 132.69, 134.13, 142.96, 147.82, 148.74, 157.97 ppm. HRMS: mass calculated for [C20H16N2O5S], 397.0858 [M + H]+ and 419.0678 [M + Na]+; obs. mass 397.0852 [M + H]+ and 419.0672 [M + Na]+. 3-(Methylsulfonyl)-4-phenyl-4H-benzo[h]chromen-2-amine, 12d. Solid. M. P.: 158−161 °C. IR (KBr): 3479, 3023, 2985, 1672, 1561, 1352, 829 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.69 (s, 3H), 5.00 (s, 1H), 6.88 (d, 2H, J = 8.3 Hz), 7.32 (s, 2H), 7.38 (d, 2H, J = 8.7 Hz), 7.42 (d, 1H, J = 8.6 Hz), 7.52 (t, 1H, J = 8.2 Hz), 7.65 (t, 1H, J = 8.9 Hz), 7.92 (d, 1H, J = 7.9 Hz), 8.34 (d, 1H, J = 8.0 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 40.52, 43.58, 83.59, 114.41, 121.22, 121.83, 123.28, 124.82, 126.53, 127.01, 128.02, 128.14, 128.85, 132.91, 138.59, 143.73, 158.42, 159.31 ppm. HRMS: mass calculated for [C20H17NO3S], 352.1007 [M + H]+ and 374.0827 [M + Na]+; obs. mass 352.1002 [M + H]+ and 374.0823 [M + Na]+. 4-(Benzo[d][1,3]dioxol-6-yl)-3-(methylsulfonyl)-4H-benzo[h]chromen-2-amine, 12c. Solid. M. P.: 205−208 °C.; IR (KBr): 3560, 3108, 2989, 1656, 1521, 1327, 849 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.68 (s, 3H), 5.00 (s, 1H), 5.94 (d, 2H, J = 7.4 Hz), 6.80 (s, 2H), 6.83 (s, 1H), 7.13 (s, 2H), 7.36 (d, 1H, J = 8.5 Hz), 7.56 (t, 1H, J = 7.7 Hz), 7.64 (t, 2H, J = 8.4 Hz), 7.89 (d, 1H, J = 7.7 Hz), 8.30 (d, 1H, J = 8.1 Hz). 13C NMR (75 MHz, DMSO-d6): δ 40.93, 43.79, 83.42, 101.39, 108.13, 108.72, 120.84, 121.27, 121.62, 123.22, 124.45, 126.52, 127.06, 128.12, 132.99, 140.60, 143.08, 146.38, 147.86, 158.05 ppm. HRMS: mass calculated for [C21H17NO5S]: 396.0905 [M + H]+ 3458


Research Article

ACS Sustainable Chemistry & Engineering and 418.0725 [M + Na]+; obs. mass 396.0906 [M + H]+ and 418.0725 [M + Na]+. 4-(4-Methoxyphenyl)-N7,N7-dimethyl-3-(phenylsulfonyl)-4Hchromene-2,7-diamine, 14a. Solid. M. P.: 202−205 °C. IR (KBr): 3454, 3307, 3060, 2906, 1622, 1385, 847 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.81 (s, 6H), 3.65 (s, 3H), 4.69 (s, 1H), 6.20 (d, 2H, J = 8.4 Hz), 6.41 (dd, 1H, J = 6.7 and 8.5 Hz), 6.67 (d, 2H, J = 8.5 Hz), 6.95 (d, 2H, J = 9.1 Hz), 7.00 (s, 1H), 7.09 (s, 2H), 7.38 (t, 2H, J = 7.6 Hz), 7.49 (t, 1H, J = 7.3 Hz), 7.64 (d, 2H, J = 7.7 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.71, 40.46, 55.47, 83.53, 99.01, 109.88, 114.02, 114.68, 126.07, 128.27, 129.17, 132.44, 139.49, 144.38, 149.34, 150.44, 157.95, 158.86 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Isopropylphenyl)-N7,N7-dimethyl-3-(phenylsulfonyl)-4Hchromene-2,7-diamine, 14b. Solid. M. P.: 168−170 °C. IR (KBr): 3451, 3350, 3052, 2873, 2220, 1620, 1345, 797 cm. 1H NMR (300 MHz, DMSO-d6): δ 1.11 (s, 3H), 1.13 (s, 3H), 2.69−2.76 (m, 1H), 2.81 (s, 6H), 4.72 (s, 1H), 6.21 (s, 1H), 6.39−6.42 (m, 1H), 6.97 (s, 5H), 7.12 (s, 2H), 7.35 (t, 2H, J = 8.4 Hz), 7.46 (t, 1H, J = 7.2 Hz), 7.61 (d, 2H, J = 7.5 Hz). 13C NMR (75 MHz, DMSO-d6): δ 24.34, 24.42, 33.47, 39.98, 40.47, 83.32, 99.02, 109.87, 114.53, 126.07, 126.49, 127.15, 129.11, 129.20, 132.41, 144.30, 144.59, 146.32, 149.34, 150.47, 158.90 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. N7,N7-Dimethyl-4-(3-nitrophenyl)-3-(phenylsulfonyl)-4H-chromene-2,7-diamine, 14c. Solid. M. P.: 222−225 °C. IR (KBr): 3445, 3297, 3082, 2896, 1631, 1526, 1279, 734 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.83 (s, 6H), 4.99 (s, 1H), 6.24 (s, 1H), 6.43 (d, 1H, J = 6.5 Hz), 7.04 (d, 1H, J = 8.5 Hz), 7.29 (s, 2H), 7.36 (t, 2H, J = 7.6 Hz), 7.44 (t, 2H, J = 7.6 Hz), 7.61 (d, 1H, J = 6.8 Hz), 7.66 (d, 2H, J = 7.2 Hz), 7.82 (s, 1H), 7.88 (d, 1H, J = 7.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.85, 40.36, 82.23, 98.95, 110.01, 112.68, 121.47, 121.74, 126.00, 129.26, 129.35, 130.29, 132.58, 134.22, 144.13, 148.04, 149.27, 149.36, 150.78, 159.12 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Bromophenyl)-N7,N7-dimethyl-3-(phenylsulfonyl)-4H-chromene-2,7-diamine, 14d. Solid. M. P.: 208−211 °C. IR (KBr): 3462, 3333, 2893, 2807, 1622, 1386, 857 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.81 (s, 6H), 4.75 (s, 1H), 6.21 (d, 1H, J = 2.1 Hz), 6.41 (dd, 1H, J = 6.6 and 8.9 Hz), 6.97 (d, 1H, J = 8.7 Hz), 7.06 (d, 2H, J = 8.3 Hz), 7.19 (s, 2H), 7.29 (d, 2H, J = 8.2 Hz), 7.40 (t, 2H, J = 7.5 Hz), 7.52 (t, 1H, J = 7.2 Hz), 7.68 (d, 2H, J = 7.5 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.85, 40.42, 82.81, 98.98, 109.93, 113.52, 119.39, 126.07, 129.28, 129.52, 131.45, 132.57, 144.20, 146.84, 149.28, 150.63, 158.96 ppm.HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. N7,N7-Dimethyl-3-(phenylsulfonyl)-4-(thiophen-2-yl)-4H-chromene-2,7-diamine, 14e. Solid. M. P.: 179−181 °C. IR (KBr): 3429, 3319, 3060, 2908, 1622, 1274, 713 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.83 (s, 6H), 5.10 (s, 1H), 6.20 (d, 1H, J = 2.1 Hz), 6.46 (dd, 1H, J = 2.3 and 8.5 Hz), 6.76 (t, 1H, J = 4.7 Hz), 6.81 (d, 1H, J = 2.7 Hz), 7.10 (d, 1H, J = 8.6 Hz), 7.14 (s, 1H), 7.16 (s, 2H), 7.43 (t, 2H, J = 7.8 Hz), 7.53 (t, 1H, J = 7.3 Hz), 7.75 (d, 2H, J = 7.5 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 35.72, 40.44, 83.86, 99.04, 109.79, 114.29, 123.56, 124.56, 126.03, 126.91, 129.04, 129.30, 132.60, 144.44, 149.66, 150.74, 152.72, 159.17 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(2-Amino-7-(dimethylamino)-3-(phenylsulfonyl)-4H-chromen4-yl)benzonitrile, 14f. Solid. M. P.: 187−189 °C. IR (KBr): 3460, 3333, 3054, 2870, 2216, 1622, 1385, 860 cm−1. 1H NMR: (300 MHz, DMSO-d6): δ 2.82 (s, 6H), 4.86 (s, 1H), 6.21 (d, 1H, J = 2.3 Hz), 6.42 (dd, 1H, J = 8.6 and 6.2 Hz), 7.00 (d, 1H, J = 8.7 Hz), 7.28 (d, 2H, J = 3.7 Hz), 7.31 (s, 1H), 7.41 (t, 2H, J = 7.7 Hz), 7.52 (t, 1H, J = 7.5 Hz), 7.58 (d, 2H, J = 8.2 Hz), 7.69 (d, 2H, J = 7.4 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.99, 40.38, 82.26, 98.99, 109.12, 112.72,

119.34, 126.08, 128.30, 129.33, 132.72, 144.05, 149.31, 150.78, 152.90, 159.09 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. N7,N7-Dimethyl-4-phenyl-3-(phenylsulfonyl)-4H-chromene-2,7diamine, 14g. Solid. M. P.: 156−159 °C. IR (KBr): 3440, 3314, 3029, 2939, 1633, 1357, 993 cm−1. 1H NMR (300 MHz, DMSO-d6): δ2.81 (s, 6H), 4.75 (s, 1H), 6.20 (d, 1H, J = 2.31 Hz), 6.41 (dd, 1H, J = 2.31 and 8.35 Hz), 6.99 (d, 1H, J = 8.7 Hz), 7.01−7.06 (m, 1H), 7.10−7.12 (m, 4H), 7.15 (brs, 2H), 7.38 (t, 2H, J = 7.7 Hz), 7.49 (t, 1H, J = 7.3 Hz), 7.65 (d, 2H, J = 7.4 Hz). 13C NMR (75 MHz, DMSO-d6): δ 40.45, 40.51, 83.12, 99.02, 109.85, 114.38, 126.07, 126.33, 127.22, 128.63, 129.22, 132.52, 144.24, 147.31, 149.37, 150.50, 159.03 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Chlorophenyl)-N7,N7-dimethyl-3-(phenylsulfonyl)-4H-chromene-2,7-diamine, 14H. Solid. M. P.: 184−187 °C. IR (KBr): 3471, 3343, 2893, 1627, 1385, 853 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.81 (s, 6H), 4.77 (s, 1H), 6.21 (d, 1H, J = 2.5 Hz), 6.41 (dd, 1H, J = 6.2 and 8.6 Hz), 6.98 (d, 1H, J = 8.5 Hz), 7.10 (d, 2H, J = 8.5 Hz), 7.17 (d, 2H, J = 8.6 Hz), 7.19 (s, 1H), 7.40 (t, 2H, J = 7.7 Hz), 7.51 (t, 1H, J = 7.5 Hz), 7.68 (d, 2H, J = 7.3 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.71, 40.41, 82.87, 98.99, 109.92, 113.62, 126.07, 128.52, 129.12, 129.26, 130.92, 132.57, 144.21, 146.39, 149.30, 150.62, 158.98 ppm.HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(2,6-Dimethoxyphenyl)-N7,N7-dimethyl-3-(phenylsulfonyl)-4Hchromene-2,7-diamine, 14i. Solid. M.P.: 228−231 °C; IR (KBr): 3466, 3345, 3078, 2900, 2205, 1634, 1375, 680 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.80 (s, 6H), 3.53 (s, 3H), 3.67 (s, 3H), 5.08 (s, 1H), 6.18 (s, 1H), 6.36−6.40 (m, 2H), 6.55 (dd, 1H, J = 6.2 and 7.6 Hz), 6.69 (d, 1H, J = 7.4 Hz), 6.99 (d, 1H, J = 8.1 Hz), 7.14 (s, 2H), 7.35 (t, 2H, J = 8.5 Hz), 7.46 (t, 1H, J = 7.2 Hz), 7.58 (d, 1H, J = 7.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.99, 40.38, 82.26, 98.99, 109.12, 112.72, 119.34, 126.08, 128.30, 129.33, 132.72, 144.05, 149.31, 150.78, 152.90, 159.09 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. N7,N7-Dimethyl-3-(phenylsulfonyl)-4-p-tolyl-4H-chromene-2,7diamine, 14j. Solid. M. P.: 159−162 °C. IR (KBr): 3452, 3307, 2994, 2897, 1633, 1520, 1385, 847 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.17 (s, 3H), 2.81 (s, 6H), 4.67 (s, 1H), 6.20 (s, 1H), 6.37 (d, 1H, J = 8.4 Hz), 6.88 (d, 2H, J = 8.1 Hz), 6.95 (t, 2H, J = 7.8 Hz), 7.06 (s, 2H), 7.34 (t, 2H, J = 7.7 Hz), 7.46 (t, 1H, J = 7.3 Hz), 7.62 (d, 2H, J = 7.9 Hz). 13C NMR (75 MHz, DMSO-d6): δ 20.96, 40.19, 40.46, 83.41, 99.05, 109.74, 114.40, 126.04, 127.20, 128.99, 129.02, 129.12, 132.21, 135.23, 144.33, 149.32, 150.38, 158.87 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Methoxyphenyl)-N7,N7-dimethyl-3-(methylsulfonyl)-4Hchromene-2,7-diamine, 15a. Solid. M. P.: 163−165 °C. IR (KBr): 3432, 3354, 3091, 2900, 2222, 1630, 1345, 960 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.42 (s, 3H), 2.85 (s, 6H), 3.68 (s, 3H), 4.71 (s, 1H), 6.24 (d, 1H, J = 8.5 Hz), 6.38−6.41 (m, 1H), 6.68 (s, 2H), 6.76 (d, 2H, J = 8.8 Hz), 6.88 (d, 1H, J = 8.1 Hz), 7.09 (d, 2H, J = 7.3 Hz). 13C NMR (75 MHz, DMSO-d6): δ 39.63, 40.48, 43.68, 55.27, 83.99, 98.99, 109.69, 114.08, 128.56, 129.34, 139.33, 149.33, 150.32, 158.00, 158.16 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081[M + Na]+. N7,N7-Dimethyl-3-(methylsulfonyl)-4-(3-nitrophenyl)-4H-chromene-2,7-diamine, 15b. Solid. M. P.: 185−187 °C. IR (KBr):3430, 3378, 2998, 2856, 2212, 1612, 1299, 786 cm−1;1H NMR (300 MHz, DMSO-d6): δ 2.58 (s, 3H), 2.85 (s, 6H), 4.90 (s, 1H), 6.26 (d, 1H, J = 6.9 Hz), 6.36 (d, 1H, J = 7.0 Hz), 6.62 (brs, 2H), 6.84−6.88 (m, 1H), 7.39−7.44 (m, 1H), 7.58 (d, 1H, J = 8.5 Hz), 7.92 (d, 1H, J = 7.8 Hz), 7.98 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 40.35, 40.92, 43.33, 83.13, 99.11, 109.69, 112.05, 121.47, 122.11, 129.17, 129.75, 133.97, 3459


Research Article


122.70, 122.86, 126.24, 128.27, 129.37, 130.28, 131.43, 132.16, 132.85, 138.98, 143.25, 143.68, 150.25, 157.44 ppm. HRMS: mass calculated for [C25H19ClN2O4S], 479.0833 [M + H]+ and 501.0652 [M + Na]+; obs. mass 479.0833 [M + H]+ and 501.0653 [M + Na]+. 2-Amino-6-methyl-4-phenyl-3-(phenylsulfonyl)-4H-pyrano[3,2c]quinolin-5(6H)-one, 17f. Solid. M. P.: 218−222 °C. IR (KBr): 3492, 3378, 3024, 2885, 2192, 1622, 1372, 832 cm−1. 1H NMR: (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.82 (s, 1H), 7.05−7.08 (m, 1H), 7.01 (t, 2H, J = 7.7 Hz), 7.16 (d, 2H, J = 6.8 Hz), 7.35 (t, 1H, J = 7.5 Hz), 7.39 (t, 2H, J = 7.6 Hz), 7.49 (s, 1H), 7.51 (s, 3H), 7.63−7.68 (m, 3H), 8.07 (d, 1H, J = 7.1 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.83, 36.88, 84.11, 112.56, 113.10, 115.43, 122.66, 122.80, 126.23, 126.83, 128.36, 129.32, 132.05, 132.80, 138.91, 143.72, 144.27, 150.21, 157.55, 160.05 ppm. HRMS: mass calculated for [C25H20N2O4S], 445.1223 [M + H]+ and 467.1042 [M + Na]+; obs. mass 445.1220 [M + H]+ and 467.1039 [M + Na]+. 4-(2-Amino-5,6-dihydro-6-methyl-5-oxo-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-4-yl) Benzonitrile, 17g. Solid. M. P.: 206− 208 °C. IR (KBr): 3441, 3319, 3126, 2945, 2225, 1600, 1372, 840, 726 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.50 (s, 3H), 4.84 (s, 1H), 7.34−7.40 (m, 3H), 7.43 (d, 2H, J = 7.7 Hz), 7.52 (t, 2H, J = 8.2 Hz), 7.57 (d, 2H, J = 8.2 Hz), 7.65 (s, 3H), 7.70 (d, 2H, J = 7.4 Hz), 8.07 (d, 1H, J = 7.9 Hz). 13C NMR(75 MHz, DMSO-d6): δ 29.85, 37.31, 83.06, 109.63, 111.09, 112.93, 115.50, 119.24, 122.76, 122.93, 126.23, 129.43, 129.58, 132.34 132.97, 139.07, 143.54, 149.75, 150.48, 157.49, 159.95 ppm. HRMS: mass calculated for [C26H19N3O4S], 470.1175 [M + H]+ and 492.0994 [M + Na]+; obs. mass 470.1172 [M + H]+ and 492.0992 [M + Na]+. 4-(4-(Allyloxy)phenyl)-2-amino-6-methyl-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17h. Solid. M. P.: 218−220 °C. IR (KBr): 3439, 3321, 3054, 2981, 1665, 1360, 754 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.45 (d, 2H, J = 4.6 Hz), 4.77 (s, 1H), 5.22 (d, 1H, J = 10.6 Hz), 5.36 (d, 1H, J = 17.1 Hz), 5.92− 6.03 (m, 1H), 6.68 (d, 2H,J = 8.3 Hz), 7.05 (d, 2H, J = 8.4 Hz), 7.33 (d, 1H, J = 7.0 Hz), 7.40 (t, 2H, J = 7.9 Hz), 7.43−7.53 (m, 4H), 7.62−7.68 (m, 3H), 8.06 (d, 1H, J = 7.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.81, 36.03, 68.58, 84.36, 112.71, 113.12, 114.57, 115.40, 117.70, 122.65, 122.76, 126.25, 129.29, 129.34, 131.98, 132.76, 134.29, 136.47, 138.83, 143.80, 149.99, 157.25, 157.42, 160.07 ppm. HRMS: mass calculated for [C28H24N2O5S], 501.1485 [M + H]+ and 523.1304 [M + Na]+; obs. mass 501.1488 [M + H]+ and 523.1309 [M + Na]+. 2-Amino-4-(3,4-dimethoxyphenyl)-6-methyl-3-(phenylsulfonyl)4H-pyrano[3,2-c]quinolin-5(6H)-one, 17i. Solid. M. P.: 138−141 °C. IR (KBr): 3454, 3348, 2931, 2825, 1601, 1258, 759, cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.52 (s, 3H), 3.56 (s, 3H), 3.64 (s, 3H), 4.80 (s, 1H), 6.68 (s, 3H), 7.34 (d, 1H, J = 7.5 Hz), 7.40 (t, 2H, J = 7.6 Hz), 7.50 (s, 4H), 7.61−7.66 (m, 3H), 8.06 (d, 1H, J = 8.0 Hz). 13 C NMR (75 MHz, DMSO-d6): δ 29.83, 36.37, 55.79, 56.06, 84.14, 112.21, 112.50, 112.58, 113.14, 115.37, 120.55, 122.62, 122.77, 126.27, 129.15, 131.95, 132.67, 136.48, 138.83, 143.81, 148.08, 148.57, 149.98, 157.50, 160.16 ppm. HRMS: mass calculated for [C27H24N2O6S], 505.1434 [M + H]+ and 527.1253 [M + Na]+; obs. mass 505.1434 [M + H]+ and 527.1252 [M + Na]+. 2-Amino-4-(4-isopropylphenyl)-6-methyl-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17j. Solid. M.P.: 178−181 °C. IR (KBr): 3464, 3328, 3055, 2960, 1670, 1368, 723 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 1.09 (s, 3H), 1.11 (s, 3H), 2.69−2.73 (m, 1H),3.52 (s, 3H), 4.80 (s, 1H), 6.87 (d, 2H, J = 7.8 Hz), 7.04 (d, 2H, J = 8.0 Hz), 7.28 (s, 3H), 7.38 (s, 4H), 7.56 (s, 2H), 7.58 (s, 1H), 8.06 (d, 1H, J = 7.9 Hz). 13C NMR (75 MHz, DMSO-d6): δ 24.20, 24.25, 29.67, 33.52, 36.42, 84.42, 112.54, 113.30, 114.84, 122.33, 122.85, 126.03, 126.17, 128.32, 131.59, 132.29, 138.81, 141.21, 143.79, 146.66, 150.09, 157.43, 160.17 ppm. HRMS: mass calculated for [C28H26N2O4S], 487.1692 [M + H]+ and 509.1511 [M + Na]+; obs. mass 487.1692 [M + H]+ and 509.1511 [M + Na]+. 2-Amino-6-methyl-3-(phenylsulfonyl)-4-(thiophen-2-yl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17k. Solid. M. P.: 189−192 °C. IR (KBr): 3441, 3322, 3016, 2928, 2212, 1666, 1361, 756 cm−1. 1 H NMR (300 MHz, DMSO-d6): δ 3.57 (s, 3H), 5.17 (s, 1H),

148.29, 149.40, 149.66, 150.58, 158.52 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Isopropylphenyl)-N7,N7-dimethyl-3-(methylsulfonyl)-4Hchromene-2,7-diamine, 15c. Solid. M. P.: 156−158 °C. IR (KBr): 3434, 3355, 2903, 2881, 2221, 1654, 1290, 780 cm−1; 1H NMR (300 MHz, DMSO-d6): δ 1.12 (s, 3H), 1.15 (s, 3H), 2.51 (s, 3H), 2.75−2.79 (m, 1H), 2.84 (s, 6H), 4.74 (s, 1H), 6.27 (s, 1H), 6.46 (d, 1H, J = 8.2 Hz), 6.81 (s, 1H), 6.99 (d, 1H, J = 8.7 Hz), 7.11 (s, 4H). 13 C NMR (75 MHz, DMSO-d6): δ 24.30, 24.38, 33.43, 40.53, 43.57, 83.74, 99.04, 109.88, 114.42, 126.80, 127.34, 129.43, 144.93, 146.72, 149.48, 150.52, 158.29 ppm.HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 2-Amino-4-(4-methoxyphenyl)-6-methyl-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17a. Solid. M.P.: 199−201 °C. IR (KBr): 3426, 3322, 3071, 2838, 1667, 1367, cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.93 (s, 1H), 7.34−7.37 (m, 2H), 7.40 (s, 1H), 7.45 (t, 2H, 1H, J = 7.7 Hz), 7.52 (d, 2H, 1H, J = 8.6 Hz), 7.66 (s, 2H), 7.68 (s, 2H), 7.72 (s, 2H), 7.85 (s, 1H), 7.91 (d, 1H, 1H, J = 8.4 Hz), 8.11 (d, 1H, 1H, J = 7.8 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.87, 37.04, 82.88, 110.90, 112.92, 115.54, 122.00, 122.80, 122.94, 122.99, 126.14, 129.37, 129.95, 132.36, 132.87, 135.41, 139.13, 143.64, 145.99, 147.79, 157.53, 159.99 ppm. HRMS: mass calculated for [C26H22N2O5S], 475.1328 [M + H]+ and 497.1147 [M + Na]+; obs. mass 475.1324 [M + H]+ and 497.1143 [M + Na]+. 2-Amino-6-methyl-3-(phenylsulfonyl)-4-p-tolyl-4H-pyrano[3,2-c]quinolin-5(6H)-one, 17b. Solid. M. P.: 167−170 °C. IR (KBr):3440, 3306, 3120, 2934, 1665, 1360, 754 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 2.17 (s, 3H), 3.50 (s, 3H), 4.77 (s, 1H),6.90 (d, 2H, J = 8.3 Hz), 7.05 (d, 2H, J = 8.3 Hz), 7.34 (t, 1H, J = 7.7 Hz), 7.40 (t, 2H, J = 8.6 Hz), 7.47−7.54 (m, 4H), 7.63 (d, 1H, J = 8.0 Hz), 7.67 (d, 2H, J = 7.7 Hz), 8.06 (d, 1H, 1H, J = 8.0 Hz). 13C NMR (75 MHz, DMSO-d6): δ 20.99, 29.79, 36.47, 84.31, 112.64, 113.11, 115.39, 122.63, 122.76, 126.24, 128.28, 128.89, 129.29, 131.98, 132.71, 135.90, 138.86, 141.40, 143.78, 150.05, 157.43, 160.04 ppm. HRMS: mass calculated for [C26H22N2O4S], 459.1379 [M + H]+ and 481.1198 [M + Na]+; obs. mass 459.1375 [M + H]+ and 481. 1194 [M + Na].+ 2-Amino-6-methyl-4-(3-nitrophenyl)-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17c. Solid. M. P.: 188−190 °C. IR (KBr): 3419, 3317, 2915, 1601, 1360, 808, 756 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.93 (s, 1H), 7.34−7.37 (m, 2H), 7.40 (s, 1H), 7.45 (t, 2H, J = 7.7 Hz), 7.52 (d, 2H, J = 8.6 Hz), 7.66 (s, 2H), 7.68 (s, 2H), 7.72 (s, 2H), 7.85 (s, 1H), 7.91 (d, 1H, J = 8.4 Hz), 8.11 (d, 1H, J = 7.8 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.87, 37.04, 82.88, 110.90, 112.92, 115.54, 122.00, 122.80, 122.94, 122.99, 126.14, 129.37, 129.95, 132.36, 132.87, 135.41, 139.13, 143.64, 145.99, 147.79, 157.53, 159.99 ppm. HRMS: mass calculated for [C25H19N3O6S], 490.1074 [M + H]+ and 512.0893 [M + Na]+; obs. mass 490.1072 [M + H]+ and 512.0892 [M + Na]+. 2-Amino-4-(4-bromophenyl)-6-methyl-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17d. Solid. M. P.: 223−225 °C. IR (KBr): 3445, 3333, 2939, 1668, 1361, 755 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.50 (s, 3H), 4.76 (s, 1H), 7.12 (d, 2H, J = 8.5 Hz), 7.29 (d, 2H, J = 8.3 Hz), 7.35 (t, 1H, J = 7.6 Hz), 7.42 (t, 2H, J = 7.6 Hz), 7.52 (t, 2H, J = 8.3 Hz), 7.58 (s, 2H), 7.64 (d, 1H, J = 7.7 Hz), 7.69 (d, 2H, J = 7.3 Hz), 8.07 (d, 1H, 1H, J = 7.2 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.83, 36.57, 83.60, 111.73, 113.00, 115.47, 119.96, 122.71, 122.85, 126.23, 129.38, 130.69, 131.20, 132.17, 132.85, 143.65, 143.71, 150.21, 157.40, 159.98 ppm. HRMS: mass calculated for [C25H19BrN2O4S], 523.0328 [M + H]+ and 545.0147 [M + Na]+; obs. mass 523.0331 [M + H]+ and 545.0152 [M + Na]+. 2-Amino-4-(4-chlorophenyl)-6-methyl-3-(phenylsulfonyl)-4Hpyrano[3,2-c]quinolin-5(6H)-one, 17e. Solid. M. P.: 204−207 °C. IR (KBr): 3433, 3306, 2927, 2828, 1599, 838, cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.79 (s, 1H), 7.16 (s, 3H), 7.34 (d, 1H, J = 7.4 Hz), 7.38 (d, 1H, J = 7.9 Hz), 7.43 (d, 2H, J = 7.8 Hz), 7.49−7.53 (m, 2H), 7.57 (s, 2H), 7.65 (d, 1H, J = 7.4 Hz), 7.69 (d, 2H, J = 7.7 Hz), 8.01 (d, 1H, J = 7.9 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.83, 36.49, 83.68, 111.82, 113.02, 115.47, 3460


Research Article


DMSO-d6): δ 4.40 (d, 1H, J = 3.2 Hz), 4.92 (s, 1H), 5.19 (d, 1H, J = 10.8 Hz), 5.32 (d, 1H, J = 17.2 Hz), 5.91−6.00 (m, 1H), 6.62 (d, 2H, J = 8.0 Hz), 7.05 (d, 2H, J = 8.0 Hz), 7.09 (d, 1H, J = 4.4 Hz), 7.16 (t, 1H, J = 9.2 Hz), 7.33−7.43 (m, 7H), 7.67 (d, 2H, J = 6.6 Hz), 8.54 (d, 1H, J = 7.2 Hz), 11.27 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 40.34, 68.56, 83.47, 107.93, 110.52, 111.02, 114.62, 116.05, 117.41, 119.17, 120.72, 123.64, 125.72, 125.89, 126.07, 128.46, 128.89, 132.17, 134.03, 139.63, 139.98, 140.07, 143.50, 144.40, 156.91, 158.65 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(2-Amino-4,7-dihydro-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-4-yl)benzonitrile, 20d. Solid. M. P.: 206−208 °C. IR (KBr): 3572, 3074, 2938, 1653, 1362, 892, 776 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.14 (s, 1H), 7.16 (d, 1H, J = 8.2 Hz), 7.20 (d, 2H, J = 8.6 Hz), 7.39 (s, 2H), 7.42 (s, 2H), 7.45 (d, 2H, J = 3.5 Hz), 7.49 (d, 1H, J = 4.9 Hz), 7.53 (d, 1H, J = 7.4 Hz), 7.59 (d, 2H, J = 8.1 Hz), 7.68 (s, 2H), 7.76 (d, 2H, J = 7.5 Hz), 8.60 (d, 1H, J = 7.9 Hz), 11.44 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 40.92, 82.22, 108.34, 109.20, 110.51, 111.26, 114.70, 119.32, 119.45, 120.53, 123.76, 126.01, 126.13, 128.52, 129.36, 132.77, 140.01, 140.40, 143.51, 144.12, 153.07, 158.91 ppm.HRMS: mass calculated for [C26H21NO4S], 444.1269 [M+ H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(2,5-dimethylphenyl)-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 20e. Solid. M. P.: 238−240 °C. IR (KBr): 3581, 3067, 2954, 1657, 1351, 899, 781 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 1.91 (s, 3H), 2.45 (s, 3H), 5.30 (s, 1H), 6.63 (s, 1H), 6.68 (d, 1H, J = 6.8 Hz), 6.86 (d, 1H, J = 7.6 Hz), 6.97 (d, 1H, J = 8.2 Hz), 7.13 (d, 1H, J = 7.4 Hz), 7.20 (t, 1H, J = 7.5 Hz), 7.30 (d, 2H, J = 7.3 Hz), 7.40 (d, 1H, J = 8.2 Hz), 7.44 (d, 2H, J = 7.2 Hz), 7.50 (d, 2H, J = 5.3 Hz), 7.54 (brs, 2H), 8.62 (d, 1H, J = 7.7 Hz), 11.41 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 19.37, 20.99, 36.80, 83.15, 108.20, 110.29, 111.22, 115.39, 119.37, 120.73, 123.80, 125.83, 126.01, 127.07, 128.87, 129.81, 130.59, 131.41, 132.28, 135.31, 139.98, 140.06, 143.23, 144.29, 144.90, 158.29 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(3,4-dimethoxyphenyl)-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 20f. Solid. M. P.: 202−205 °C. IR (KBr): 3593, 3075, 2945, 1662, 1365, 840, 729 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.54 (s, 3H), 3.63 (s, 3H), 4.98 (s, 1H), 6.68 (s, 3H), 7.14 (d, 1H, J = 8.3 Hz), 7.20 (t, 2H, J = 8.2 Hz), 7.34 (d, 1H, J = 7.7 Hz), 7.40 (d, 2H, J = 8.0 Hz), 7.46 (d, 2H, J = 7.4 Hz), 7.53 (s, 2H), 7.67 (d, 2H, J = 7.7 Hz), 8.57 (d, 1H, J = 7.7 Hz), 11.39 (s, 1H). 13 C NMR (75 MHz, DMSO-d6): δ 40.51, 55.74, 56.04, 83.17, 108.02, 110.36, 111.19, 111.44, 112.35, 116.20, 119.31, 119.54, 120.65, 123.73, 125.98, 126.16, 129.04, 132.40, 139.86, 139.98, 140.08, 143.40, 144.47, 148.89, 158.68 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(3,4,5-trimethoxyphenyl)-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 20g. Solid. M. P.: 218−221 °C. IR (KBr): 3555, 3057, 2925, 1632, 1344, 867, 782 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.54 (s, 3H), 3.57 (s, 6H), 5.05 (s, 1H), 6.39 (s, 2H), 7.19 (t, 2H, J = 8.1 Hz), 7.31 (t, 1H, J = 8.3 Hz), 7.36 (d, 2H, J = 7.8 Hz), 7.41 (d, 1H, J = 7.2 Hz), 7.46 (t, 2H, J = 7.8 Hz), 7.61 (s, 2H), 7.65 (d, 2H, J = 9.8 Hz), 8.60 (d, 1H, J = 7.8 Hz), 11.41 (s, 1H). 13 C NMR (75 MHz, DMSO-d6): δ 41.25, 56.08, 60.24, 82.69, 104.85, 108.05, 110.36, 111.21, 115.64, 119.33, 120.69, 123.78, 126.00, 126.16, 126.28, 128.89, 132.40, 136.23, 140.00, 142.23, 143.32, 144.51, 152.99, 158.74 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(5-nitrobenzo[d][1,3]dioxol-6-yl)-3(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 20h. Solid. M. P.: 212−215 °C. IR (KBr): 3543, 3098, 2981, 1661, 1369, 908, 796 cm−1. 1 H NMR (300 MHz, DMSO-d6): δ 5.80 (s, 1H), 6.00 (s, 2H), 6.37 (s, 1H), 7.21 (t, 2H, J = 8.0 Hz), 7.30 (d, 1H, J = 8.6 Hz), 7.37 (s, 1H), 7.46 (d, 2H, J = 8.3 Hz), 7.52 (t, 1H, J = 7.1 Hz), 7.65 (d, 2H,

6.77 (t, 1H, J = 4.9 Hz), 6.86 (d, 1H, J = 3.1 Hz), 7.16 (d, 1H, J = 4.5 Hz), 7.33 (d, 1H, J = 7.5 Hz), 7.38 (t, 1H, J = 4.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.92, 31.82, 84.14, 112.31, 113.01, 115.46, 122.74, 124.82, 124.99, 126.22, 126.94, 129.48, 132.18, 132.96, 138.86, 143.81, 148.84, 150.35, 157.82, 159.99 ppm. HRMS: mass calculated for [C23H18N2O4S2], 451.0787 [M + H]+ and 473.0606 [M + Na]+; obs. mass 451.0786 [M + H]+ and 473.0607 [M + Na]+. 2-Amino-6-methyl-3-(methylsulfonyl)-4-(3-nitrophenyl)-4,6-dihydro-5H-pyrano[3,2-c]quinolin-5-one, 18a. Solid. M. P.: 192−195 °C. IR (KBr): 3441, 3322, 3016, 2928, 2212, 1666, 1361, 756 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.57 (s, 3H), 5.17 (s, 1H), 6.77 (t, 1H, J = 4.9 Hz), 6.86 (d, 1H, J = 3.1 Hz), 7.16 (d, 1H, J = 4.5 Hz), 7.33 (d, 1H, J = 7.5 Hz), 7.38 (t, 1H, J = 4.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.92, 31.82, 84.14, 112.31, 113.01, 115.46, 122.74, 124.82, 124.99, 126.22, 126.94, 129.48, 132.18, 132.96, 138.86, 143.81, 148.84, 150.35, 157.82, 159.99 ppm. HRMS: mass calculated for [C20H17N3O6S], 428.0917 [M + H]+ and 450.0736 [M + Na]+; obs. mass 428.0914 [M + H]+ and 450.0734 [M + Na]+. 2-Amino-4-(4-methoxyphenyl)-6-methyl-3-(methylsulfonyl)-4,6dihydro-5H-pyrano[3,2-c]quinolin-5-one, 18b. Solid. M. P.: 195− 198 °C. IR (KBr): 3444, 3311, 3132, 2999, 1643, 1389, 871 cm−1. 1 H NMR (300 MHz, DMSO-d6): δ 2.53 (s, 3H), 3.55 (s, 3H), 3.68 (s, 3H), 4.80 (s, 1H), 6.82 (d, 2H, J = 8.6 Hz), 7.16 (brs, 2H), 7.19 (d, 2H, J = 8.7 Hz), 7.39 (t, 1H, J = 7.5 Hz), 7.55 (d, 1H, J = 8.5 Hz), 7.69 (t, 1H, J = 7.8 Hz), 8.09 (d, 1H, J = 7.7 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.79, 36.08, 43.83, 55.46, 84.72, 112.49, 113.21, 114.09, 115.44, 122.65, 122.79, 129.52, 131.95, 136.55, 138.92, 150.05, 156.71, 158.46, 160.19 ppm. HRMS: mass calculated for [C21H20N2O5S], 413.1172 [M + H]+ and 435.0991 [M + Na]+; obs. mass 413.1170 [M + H]+ and 435.0989 [M + Na]+. 2-Amino-6-methyl-3-(methylsulfonyl)-4-(3-methylthiophen-2-yl)4,6-dihydro-5H-pyrano[3,2-c]quinolin-5-one, 18c. Solid. M. P.: 215−218 °C. IR (KBr): 3477, 3301, 3091, 3012, 1667, 1444, 812 cm−1. 1 H NMR (300 MHz, DMSO-d6): δ 2.35 (s, 3H), 2.51 (s, 3H), 3.58 (s, 3H), 5.18 (s, 1H), 6.71 (d, 1H, J = 5.0 Hz), 7.20 (brs, 2H), 7.22 (d, 1H, J = 5.1 Hz), 7.40 (t, 1H, J = 7.5 Hz), 7.57 (d, 1H, J = 8.5 Hz), 7.71 (t, 1H, J = 7.9 Hz), 8.09 (d, 1H, J = 7.6 Hz). 13C NMR (75 MHz, DMSO-d6): δ 14.03, 29.86, 30.35, 43.83, 85.07, 112.01, 113.12, 115.53, 122.73, 122.82, 123.85, 130.06, 132.15, 134.74, 138.96, 142.98, 149.96, 156.33, 160.15 ppm. HRMS: mass calculated for [C19H18N2O4S2], 403.0787 [M + H]+ and 425.0606 [M + Na]+; obs. mass 403.0785 [M + H]+ and 425.0604 [M + Na]+. 4,7-Dihydro-4-(4-methoxyphenyl)-3-(phenylsulfonyl)pyrano[3,2c]carbazol-2-amine, 20a. Solid. M. P.: 165−167 °C. IR (KBr): 3542, 3097, 2944, 1661, 1560, 888, 726 cm−1. 1H NMR (300 MHz, DMSOd6): δ 3.64 (s, 3H), 4.97 (s, 1H), 6.67 (d, 2H, J = 8.6 Hz), 7.09 (d, 2H, J = 8.4 Hz), 7.15 (s, 2H), 7.20 (d, 1H, J = 7.5 Hz), 7.37 (s,1H), 7.41 (d, 2H, J = 7.0 Hz), 7.46 (s, 2H), 7.50 (d, 2H, J = 6.6 Hz), 7.72 (d, 2H, J = 7.6 Hz), 8.58 (d, 1H, J = 7.7 Hz), 11.40 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 40.52, 55.45, 79.64, 83.46, 108.08, 110.44, 111.20, 114.06, 116.46, 119.34, 120.64, 123.71, 126.12, 128.47, 129.19, 132.48, 139.74, 140.00, 140.08, 143.51, 144.43, 157.99, 158.69 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-Bromophenyl)-4,7-dihydro-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 20b. Solid. M. P.: 226−228 °C. IR (KBr): 3519, 3027, 2955, 1653, 1320, 822, 742 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.02 (s, 1H), 7.14 (s, 1H), 7.16 (s, 2H), 7.19 (d, 1H, J = 7.5 Hz), 7.31 (d, 2H, J = 8.3 Hz), 7.37−7.41 (m, 4H), 7.48−7.54 (m, 2H), 7.61 (s, 2H), 7.75 (d, 2H, J = 7.5 Hz), 8.58 (d, 1H, J = 7.8 Hz), 11.44 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 40.50, 82.74, 108.23, 110.45, 111.24, 115.40, 119.40, 119.49, 120.56, 123.73, 126.12, 129.30, 129.73, 131.51, 132.60, 139.99, 140.24, 143.46, 144.24, 147.08, 158.76 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4-(4-(Allyloxy)phenyl)-4,7-dihydro-3-(phenylsulfonyl)pyrano[3,2c]carbazol-2-amine, 20c. Solid. M. P.: 218−221 °C. IR (KBr): 3529, 3045, 2943, 1651, 1371, 881, 716 cm−1. 1H NMR (300 MHz, 3461


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ACS Sustainable Chemistry & Engineering Notes

J = 7.3 Hz), 7.72 (brs, 2H), 8.63 (d, 1H, J = 7.3 Hz), 11.51 (s, 1H). 13 C NMR (75 MHz, DMSO-d6): δ 34.60, 83.06, 103.51, 104.33, 108.71, 108.95, 110.49, 111.30, 113.20, 119.51, 120.63, 123.89, 125.57, 125.66, 126.19, 129.39, 132.74, 138.30, 140.02, 140.56, 142.55, 143.70, 144.20, 146.46, 151.69, 158.63 ppm. HRMS: mass calculated for [C26H21NO4S]: 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-3-(methylsulfonyl)-4-(thiophen-2-yl)pyrano[3,2-c]carbazol-2-amine,21a. Solid. M. P.: 198−201 °C. IR (KBr): 3544, 3017, 2916, 1651, 1320, 988, 876 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 5.37 (s, 1H), 6.78 (dd, 1H, J = 3.4 and 5.0 Hz), 6.90 (d, 1H, J = 3.1 Hz), 7.16 (d, 2H, J = 7.8 Hz), 7.21 (d, 1H, J = 8.1 Hz), 7.32 (d, 1H, J = 8.3 Hz), 7.39 (t, 2H, J = 7.4 Hz), 7.44 (d, 2H, J = 4.6 Hz), 7.47 (d, 1H, J = 5.0 Hz), 7.51 (d, 1H, J = 7.1 Hz), 7.56 (s, 2H), 7.81 (d, 1H, J = 7.2 Hz), 8.55 (d, 1H, J = 7.8 Hz), 11.45 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 36.24, 83.70, 108.15, 110.46, 111.23, 116.17, 119.40, 120.53, 123.74, 124.78, 125.92, 126.09, 126.95, 129.33, 132.65, 140.01, 140.37, 143.77, 144.46, 152.98, 158.98 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(5-methylfuran-2-yl)-3-(phenylsulfonyl)pyrano[3,2-c]carbazol-2-amine, 21b. Solid. M. P.: 207−210 °C. IR (KBr): 3532, 3074, 2935, 1663, 1368, 888, 740 cm−1. 1H NMR (300 MHz, DMSO-d6): δ 1.88 (s, 3H), 5.08 (s, 1H), 5.73 (d, 1H, J = 2.1 Hz), 6.00 (d, 1H, J = 2.9 Hz), 7.21 (s, 2H), 7.38 (d, 1H, J = 7.7 Hz), 7.41 (d, 1H, J = 2.8 Hz), 7.44 (s, 1H), 7.46 (s, 2H), 7.49 (d, 1H, J = 5.7 Hz), 7.54 (s, 2H), 7.73 (d, 2H, J = 7.4 Hz), 8.56 (d, 1H, J = 7.8 Hz), 11.40 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 13.62, 34.67, 80.58, 106.29, 106.52, 107.98, 110.40, 111.22, 113.08, 119.39, 120.56, 123.07, 126.06, 129.10, 132.38, 140.01, 140.40, 144.01, 144.24, 150.51, 155.93, 159.06 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-3-(methylsulfonyl)-4-(3-nitrophenyl)pyrano[3,2-c]carbazol-2-amine, 21c. Solid. M. P.: 162−165 °C. IR (KBr): 3567, 3077, 2952, 1664, 1381, 915, 816 cm−1. 1H NMR (300 MHz, DMSOd6): δ 2.82 (s, 3H), 5.32 (s, 1H), 7.19−7.23 (m, 2H), 7.28 (d, 1H, J = 8.3 Hz), 7.38 (s, 2H), 7.43 (d, 1H, J = 7.1 Hz), 7.50 (d, 1H, J = 8.1 Hz), 7.57 (t, 1H, J = 8.0 Hz), 7.76 (d, 1H, J = 7.6 Hz), 8.03 (d, 1H, J = 8.0 Hz), 8.15 (s, 1H), 8.62 (d, 1H, J = 7.9 Hz), 11.48 (s, 1H). 13C NMR (75 MHz, DMSO-d6): δ 43.40, 82.78, 108.37, 110.54, 111.31, 114.94, 119.48, 120.63, 121.82, 121.98, 123.75, 126.15, 126.30, 130.63, 134.53, 140.04, 140.41, 143.80, 148.25, 150.53, 158.50 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+. 4,7-Dihydro-4-(4-isopropylphenyl)-3-(methylsulfonyl)pyrano[3,2c]carbazol-2-amine, 21d. Solid. M. P.: 145−148 °C. IR (KBr): 3494, 3012, 2911, 1621, 1320, 801, cm−1. 1H NMR (300 MHz, DMSO-d6): δ 3.51 (s, 3H), 4.93 (s, 1H), 7.34−7.37 (m, 2H), 7.40 (s, 1H), 7.45 (t, 2H, J = 7.7 Hz), 7.52 (d, 2H, J = 8.6 Hz), 7.66 (s, 2H), 7.68 (s, 2H), 7.72 (s, 2H), 7.85 (s, 1H), 7.91 (d, 1H, J = 8.4 Hz), 8.11 (d, 1H, J = 7.8 Hz). 13C NMR (75 MHz, DMSO-d6): δ 29.87, 37.04, 82.88, 110.90, 112.92, 115.54, 122.00, 122.80, 122.94, 122.99, 126.14, 129.37, 129.95, 132.36, 132.87, 135.41, 139.13, 143.64, 145.99, 147.79, 157.53, 159.99 ppm. HRMS: mass calculated for [C26H21NO4S], 444.1269 [M + H]+ and 466.1089 [M + Na]+; obs. mass 444.1263 [M + H]+ and 466.1081 [M + Na]+.

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The authors declare no competing financial interest.

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ACKNOWLEDGMENTS K.S.P. and U.V.D. are thankful to the University Grants Commission (UGC), New Delhi for financial assistance [F.43221-2014/SR]. We are also grateful to the Department of Science & Technology (DST), New Delhi for financial assistance to the Department of Chemistry, Shivaji University Kolhapur under the DST-FIST program.

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The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b00484.

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REFERENCES

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