A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from

Sep 13, 2017 - A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from Pyridones: Application in the Detection of Nitroaromatics. Aniruddha ... *...
1 downloads 8 Views 1008KB Size
Download PDF
Article Cite This: J. Org. Chem. 2017, 82, 10989-10996

pubs.acs.org/joc

A Mild Rhodium Catalyzed Direct Synthesis of Quinolones from Pyridones: Application in the Detection of Nitroaromatics Aniruddha Biswas, Dipanjan Giri, Debapratim Das, Anurima De, Sanjib K. Patra,* and Rajarshi Samanta* Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India S Supporting Information *

ABSTRACT: A rhodium catalyzed direct regioselective oxidative annulation by double C−H activation is described to synthesize highly substituted quinolones from pyridones. The reaction proceeds at mild conditions with broad scope and wide functional group tolerance. These novel quinolones were explored to recognize nitroaromatic compounds.

■

INTRODUCTION Recently, polyaromatic and heteroaromatic compounds as organic π-conjugated materials have attracted significant attention due to their wide application in detection of explosive nitroaromatic compounds (NACs). 1 To prepare those heteroaromatic compounds classical methods using difunctionalized starting materials were well recognized in the literature.2 Alternative approaches using monofunctionalized arenes were also extensively studied by mainly Satoh and Miura group.3 Arguably, the most effective and direct method to synthesize benzo-fused heteroaromatics is the transition metal catalyzed dehydrogenative annulation of heteroarenes with internal alkynes (Scheme 1).4 For instance, Wu first reported the

elegant methods were emerged to construct polyarenes via oxidative annulation strategy using heteroatom containing directing groups.9,10 Moreover, Chatani group recently developed cost-effective Ni catalyzed oxidative annulaion using benzamide directing group.11 However, in contrast to these tremendous development made with functionalized arenes, there are very limited reports on transition metal catalyzed direct annulations on electron deficient nitrogen containing heterocycles especially at mild conditions.12 Quinolones are well admired in organic and medicinal chemistry for their frequent appearance in bioactive molecules and functional materials.13 The conventional synthetic methods to prepare this scaffold do not provide sufficient control over the more inert carbocycle part. In continuation with our and others works on recent direct pyridone functionalizations at its C3,14 C415 and C616 positions, we envisaged that a new synthetic strategy starting from pyridone would provide poly arylated quinolones via oxidative annulation. Herein, we report a Rh(III)-catalyzed directed dehydrogenative annulation of pyridones and alkynes to provide quinolone derivatives. Moreover, a thorough screening of the obtained molecules was executed to find a potential nitroaromatics detector.

Scheme 1. Conventional Method versus Our Approach

■

RESULTS AND DISCUSSION The required reaction parameters were initially scrutinized with various N-protected 2-pyridones and diphenyl acetylene (2a) in the presence of [(Cp*RhCl2)2] (2 mol %, Cp*= 1,2,3,4,5pentamethyl cyclopentadiene), Cu(OAc)2 (2.0 equiv), AgOAc (10 mol %) in MeOH at 100 °C. Various protecting groups like methyl (1a), benzyl (1b), acetyl (1c) and pivaloyl (1d) did not afford the desired annulated product (Table 1, entries 1−4). Gratifyingly, when 2-pyridyl group (2-Py) was chosen as the protecting group (1e), our desired annulated product was obtained in 82% isolated yield (Table 1, entry 5). To improve the yield further, several reaction conditions were explored.

transition metal catalyzed oxidative annulation of arenes without any assistance from chelation group.5 Recently, this strategy was efficiently extended by Cramer group6 and successively by Tsui and Joo group.7 Since the pioneering development of Rh(III) catalyzed directed oxidative annulations of phenylazoles with alkynes by Satoh and Miura group8a,b (Scheme 1a) and of 2-phenylpyridines with alkynes by You group8c (Scheme 1b), many transition metal catalyzed © 2017 American Chemical Society

Received: August 1, 2017 Published: September 13, 2017 10989

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry Table 1. Optimization Tablea

Scheme 2. Substrate Scoped

entry

PG

additive

solvent

temp (°C)

yield (%)b

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Me (1a) Bn (1b) Ac (1c) Piv (1d) 2-Py (1e) 2-Py 2-Py 2-Py 2-Py 2-Py 2-Py 2-Py 2-Py 2-Py 2-Py

AgOAc AgOAc AgOAc AgOAc AgOAc AgSbF6 Ag2CO3 AgNTf2 AgPF6 AgNO3 AgBF4 AgOAc AgOAc AgOAc AgOAc

MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH MeOH EtOH t AmOH MeCN

100 100 100 100 100 100 100 100 100 100 100 40 40 40 40

n.d. n.d. n.d. n.d. 82 80 80 trace 56 62 59 87 80 trace 60

a

Reaction conditions: 1a (0.1 mmol), 2a (0.22 mmol), [(Cp*RhCl2)2] (2 mol %), additive (10 mol %), Cu(OAc)2 (0.2 mmol), 100 °C, 24 h, 0.05 M. bIsolated yields. DCE = 1,2 dicholoroethane. n.d. = not detected.

Screening of other silver salts (Table 1, entries 6−11) did not improve the yield further. Satisfyingly, the isolated yield was improved to 87% (Table 1, entry 12) when the reaction was performed at 40 °C. In general, screening of other solvents (Table 1, entries 13−15) did not able to improve the isolated yields further. To explore the scope and limitations with our most favorable established catalytic system, different substituted pyridones (Scheme 2 and 3) were tested. Substitutions at the C3 position of 2-pyridones with variant electronic and steric properties provided satisfied yields of the desired products (Scheme 2, 3e−3l). Gratifyingly, pyridones with electron-donating groups at their C3 position smoothly underwent to give the desired products in good to excellent yields (Scheme 2, 3e−3j). However, electron-withdrawing groups at that position provided corresponding products in moderate to good yields (Scheme 2, 3k−3l). To our delight, C4 substituted pyridones provided the desired products in moderate to good yields (Scheme 2, 3m−3n). Interestingly, reaction of isoquinolone derivative afforded the respective annulated product in acceptable yield (Scheme 2, 3o). Next, we turned our attention to make the protocol more general by the reactions of 1e with different alkynes. Diarylalkynes having electronically varying substituents gave desired annulated products in moderate to excellent yields (Scheme 2, 4a−4f). Interestingly, 3,5ditrifluoromethyl diphenyl acetylene afforded corresponding annulated product in moderate yield (Scheme 2, 4g). It was noteworthy that sterically more challenging dinaphthyl acetylene derivative smoothly afforded respected annulated product, albeit in moderate yield (Scheme 2, 4h). Notably, heterocycle attached acetylene like dithiophenyl acetylene also provided desired annulated product in good yield (Scheme 2, 4i). We were delighted to see that less reactive dialkyl acetylenes also worked under the developed conditions with lesser yields of desired products (Scheme 2, 4j−4k).

Reaction performed at 1 gm scale. bReaction conditions: 60 °C. Reaction conditions: solvent ethanol and at 80 °C. dReaction conditions: 1e−1o (0.1 mmol), 2 (0.22 mmol), [(Cp*RhCl2)2] (2 mol %), AgOAc (10 mol %), Cu(OAc)2 (2 equiv), 40 °C, 24−36 h. a c

Scheme 3. Substrate Scopea

a

Reaction conditions: 1p−1r (0.1 mmol), diphenylacetylene (0.22 mmol), [(Cp*RhCl2)2] (2 mol %), AgOAc (10 mol %), Cu(OAc)2 (2 equiv), 40 °C, 24−36 h. Pym = 2-pyrimidyl.

Unfortunately, when we explored our reaction with unsymmetrical alkynes, there was formation of inseparable mixture of regioisomeric products. As a demonstration of scalability, pyridone 1e could be transformed into its corresponding final product in gram scale with 78% yield (Scheme 2, 3e). Strikingly, the annulation in 4-pyridone scaffold could be controlled in one double bond keeping the window open for further modifications in nitrogen containing ring (Scheme 3, 3p). Beside the formation of substituted quinolones, the method was further extended for the synthesis of acridone derivative (Scheme 3, 3q). Aside from pyridine protecting 10990

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry

the C6 position of 2-pyridone to generate rhodacycle intermediate A presumably via acetate assisted concerted metalation-deprotonation (CMD) pathway. Further, alkyne 2a coordinates at rhodium center to give intermediate B and subsequent migration of the rhodium−carbon bond across the alkyne results in the formation of a seven membered rhodacycle intermediate C. Apparently this intermediate triggers a second intramolecular C−H activation leading to a more stable five membered rhodacycle E via intermediate D. Accordingly, the five membered rhodacycle E undergoes second alkyne insertion and subsequent migration affords the desired annulated product 3e with Rh(I) species via reductive elimination. Furthermore, the active Rh(III) species is regenerated from Rh(I) species by Cu(II) mediated oxidation. In general, the initial formation of the intermediate A guided the obtained regioselectivity in the final product. Among the synthesized quinolones, 4h and 4i having substituted naphthalene and thiophene units at the fused ring system exhibit intense emission at λem of 438 and 466 nm respectively, while phenyl substituted quinolones (3h, 3i, 3m, 3o and 3q) are moderately blue emissive in solution as studied in chloroform in 1 × 10−5 M concentration at ambient temperature. The photoluminiscent quantum yields (Φ) of the synthesized emissive quinolones are in the range of 10−18% (quinine sulfate in 0.5 M H2SO4 as reference). The relevant photophysical data of all the emissive molecules are summarized (Table S2, see Supporting Information). In the recent years, large scale use of explosives by terrorist groups has prompted the scientific community to develop novel and synthetically ease small molecule based chemosensors for easy, rapid and selective detection of explosives.18 Nitroaromatic (NAC) compounds such as trinitrotoluene and picric acid are essential energetic materials and are heavily used as component in landmines and explosive materials.19 Being rigid πconjugated polyaromatic compounds, naphthalene and thiophene substituted quinolones (4h−4i) can undergo favorable supramolecular π−π interaction with nitroaromatic ring resulting in fluorescence quenching through electron transfer from quinolones to electron deficient NACs. Thus, the ability of the synthesized emissive molecules to act as small molecule fluorescent probes for the detection of NACs was investigated in solution phase (Figure 1). Interestingly, 4h having significant quantum yield (18%) shows good sensitivity toward the electron deficient nitroaromatic compounds such as nitrobenzene, nitrotoluene, 2,6-dinitrotoluene, 2,4-dinitrobenzene, 2,4-dinitrophenol and most importantly picric acid (PA). The relative emission quenching ability of 4h toward various

group, pyrimidyl protected 4-pyridone would also provide the corresponding annulated product in excellent yield (Scheme 3, 3r). Finally, the 2-pyridyl directing group was removed via twostep quaternization−hydride reduction17 process at room temperature to furnish tetraphenyl quinolone derivative 5 in very good yield (Scheme 4a). To check the electronic effects of Scheme 4. Protecting Group Removal and Control Experiments

pyridone substrates during the transformation, 1k and 1h were chosen to react with 2a under standard reaction conditions. Formation of 3k and 3h were found in 1.8:1 ratio (Scheme 4b). This result suggests that the electron-withdrawing group at the C3 position of pyridone is kinetically more favored for the developed protocol. Further, the electronic effects of alkyne substrates were studied through substrates 2a and 2f (Scheme 4c). The product ratio of 4a and 4f was found to be 2.1:1, indicating that electron-donating groups at alkyne substituents were kinetically more favored. Moreover, a kinetic isotope effect (kH/kD = 1.75) was observed from two parallel reactions of 1e and 6-[D1]-1e with 2a (for details, see the Experimental Section). On the basis of the previous literature precedents,8 a plausible mechanism for the dehydrogenative annulation of pyridones is illustrated in Scheme 5. Initially, with the help of Cu(OAc)2 and AgOAc a cationic Rh(III) species is generated. Next the pyridine directed C−H cleavage appears to occur at Scheme 5. Plausible Mechanism

Figure 1. (Left) Quenching of emission of the probe (4h in 1 × 10−5 M CHCl3) when treated with different nitroaromatics (NB: Nitrobenzene; NT: Nitrotoluene; NBA: Nitrobenzoic acid; HNB: pHydroxy nitrobenzene; DNP: 2,4-Dinitrophenol; DNT: 2,6-Dinitrotoluene; PA: Picric acid). (Right) Visual appearance of 4h before and after addition of PA under 365 nm light. 10991

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry

Preparation of Acetylenes.21 A 100 mL round-bottom flask with a magnetic stir bar was charged with copper iodide (0.1 equiv), palladium acetate (0.05 equiv), and triphenylphosphine (0.1 equiv) in acetonitrile. The solution was degassed with nitrogen for 20 min. Then, triethylamine (3 equiv), aryl iodides (1 equiv), and calcium carbide (3 equiv) were added. The mixture was stirred at room temperature overnight under nitrogen atmosphere. The reaction mixture was then filtrated through a short plug of silica gel and washed with hexane. The filtrate was evaporated under vacuum to give the desired compound. Then products were further purified by silica gel column chromatography. General Procedure for Rhodium(III) Catalyzed Synthesis of Polyarylated Quinolones from Pyridones. A 10 mL screw cap vial was charged with 1-(2-Pyridyl)-2-pyridone (0.1 mmol) dissolved in 2 mL of dry MeOH. Diphenylacetylene (0.22 mmol), [Cp*RhCl2]2 (2 mol %), AgOAc (10 mol %), Cu(OAc)2 (2 equiv) were added to the reaction mixture at the room temperature. Reaction mixture was allowed to stir for 24−36 h at 40−100 °C. After the completion of the reaction, solvent was removed under reduced pressure and purified by flash column chromatography using hexane/EtOAc (4:1−1:1, v/v) mixture as the eluant. Control Experiments. 1. Experiment with Electronically Variable 1-(2-Pyridyl)-2-pyridones. 1k (0.1 mmol) and 1h (0.1 mmol) were dissolved in 2 mL of dry MeOH. Diphenylacetylene (0.22 mmol), [Cp*RhCl2]2 (4 mol %), AgOAc (20 mol %), Cu(OAc)2 (0.4 mmol) were added to the reaction mixture at the room temperature. Reaction mixture was allowed to stir for 8 h at 40 °C. After the completion of the reaction time, solvent was removed under reduced pressure. Product (3k) 31% and (3h) 17% were purified by flash column chromatography using hexane/EtOAc (2:1−1:1, v/v) mixture as the eluant. The product ratio was calculated on the basis of the isolated yields. 2. Experiment with Electronically Variable Diphenylacetylene. Ditolylacetylene (0.1 mmol) and 2f (0.1 mmol) were dissolved in 2 mL of dry MeOH. Then 1e (0.2 mmol), [Cp*RhCl2] (4 mol %), AgOAc (20 mol %), Cu(OAc)2 (0.4 mmol) were added to the reaction mixture at the room temperature. Reaction mixture was allowed to stir for 8 h at 40 °C. After the completion of the reaction time, solvent was removed under reduced pressure. Product (4a) 43% and (4f) 20% were purified by flash column chromatography using hexane/EtOAc mixture (2:1 to 1:1, v/v) as the eluant. And the product ratio was calculated on the basis of isolated yields. 3. Large Scale Experiment. 1-(2-Pyridyl)-2-pyridone (1 g, 5.8 mmol), 1e were taken in a 25 mL sealed tube with Teflon cap and dissolved in 10 mL of dry MeOH. Diphenylacetylene (2.58 g, 14.5 mmol), [Cp*RhCl2] (1 mol %), AgOAc (10 mol %), Cu(OAc)2 (2 equiv) were added to the reaction mixture at the room temperature. Reaction mixture was allowed to stir for 36 h at 40 °C. After the completion of the reaction time, solvent was removed under reduced pressure. Product 3e was purified by flash column chromatography using hexane/EtOAc (3:1, v/v) mixture as the eluant with 78% isolated yield. 4. Directing Group Removal.22 5,6,7,8-Tetraphenyl-1-(pyridin-2yl)quinolin-2(1H)-one (3e) (350 mg, 0.66 mmol) was dissolved in 5 mL of dry CH2Cl2 in a 25 mL round-bottom flask, filled with nitrogen. It was cooled to 0 °C in an ice bath. Then MeOTf (110 μL, 1.0 mmol) was added to it and allowed to warm to room temperature with stirring for 24 h. Volatile materials were evaporated off in vacuum. The residue was dissolved in 5 mL of dry CH3OH and cooled to 0 °C. Then NaBH4 (100 mg, 2.7 mmol) was added in three portions over 10 min, and the flask was filled with nitrogen again. The reaction mixture was allowed to warm to room temperature and stirred 8 h. The reaction mixture was quenched with HCl (2 N) and extracted with ethyl acetate. Organic layer was dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The product (5) was purified by flash chromatography acetone/hexane (1:3, v/v) mixture as eluant in 72% yield. 5. KIE Experiment 1. Following the general procedure of synthesis of polyarylated quinolones, two parallel reactions were carried out with 1-(2-Pyridyl)-2-pyridone (1e) and 6-D1-1-(2-Pyridyl)-2-pyridone (6-

electron deficient nitroaromatics has been summarized as bar diagram (Figure S6, see Supporting Information), showing remarkable visual fluorescence quenching upon the addition of picric acid which can be visualized by naked eye (Figure S11, see Supporting Information). The quenching behavior of the probe-NAC supramolecular complex was analyzed by the Stern−Volmer (SV) equation, I0/I = 1 + KSV[Q], where I0 and I are the fluorescence intensities in the absence and presence of the quencher [Q] (KSV is the Stern−Volmer rate constant). The linear response in Stern−Volmer plot for 4h, upon incremental addition of PA (Figure S10, see Supporting Information), suggest static quenching mechanism. The highest quenching response was observed for PA with the KSV value of 1.36 × 104 M−1 with excellent detection limit in the range of 2.2 × 10−7 M (52 ppm) demonstrating 4h as a selective and efficient sensor for explosive picric acid. In summary, we have demonstrated a Rh(III) catalyzed simple, efficient, site selective, dehydrogenative annulation method for the preparation of poly arylated quinolones directly from pyridones. The pyridyl directing group can smoothly be removed after operation. The reaction proceeded at mild condition with broad scope and wide functional group tolerance. The developed protocol would ensure an access toward novel π-conjugated organic molecules for the detection of nitroaromatics. Highly blue-green light emitting nature of this class of functionalized quinolones can also be explored as active materials in OLED application. To obtain more potent nitroaromatics detector, modification of final polyarylated quinolones is under progress.

■

EXPERIMENTAL SECTION

General Information. Unless otherwise noted, all commercially available compounds were used as provided without further purification. Solvents for chromatography were technical grade. Analytical thin layer chromatography (TLC) was performed on Merck precoated silica gel 60 F254. Visualization on TLC was achieved by the use of UV light (254 nm). Solvents mixtures were understood as volume/volume. Column chromatography was undertaken on silica gel (230−400 mesh). Chemical shifts were quoted in parts per million (ppm) referenced to the appropriate solvent peak or 0.0 ppm for tetramethylsilane. The following abbreviations were used to describe peak splitting patterns when appropriate: br = broad, s = singlet, d = doublet, t = triplet, q = quartet, dd = doublet of doublet, td = triplet of doublet, ddd = doublet of doublet of doublet, m = multiplet. Coupling constants, J, were reported in hertz unit (Hz). The spectra were fully decoupled by broad band proton decoupling. Chemical shifts were reported in ppm referenced to the center of a triplet at 77.16 ppm of chloroform-d (CDCl3). In case of Infrared (IR) spectra frequencies are given in reciprocal centimeters (cm−1), only selected absorbance peaks are reported and KBr is used as the matrix. Materials were obtained from commercial suppliers or prepared according to standard procedures unless otherwise noted. Substrates which are not commercially available were synthesized according to the reported procedures. General Procedure for the Synthesis of Substituted 1-(2Pyridyl)-2-pyridones.20 Substituted 2-hydroxypyridine (1 mmol), copper(I) iodide (10 mol %), and potassium carbonate (1 mmol) were added to DMSO (2 mL), and then 2-bromopyridine (2 mmol) was added. The mixture was stirred at 150 °C for 12 h under nitrogen atmosphere. The resulting mixture was allowed to cool to room temperature and then quenched with water. Organic layer was extracted with ethyl acetate, concentration under reduced pressure, and purified with silica gel column chromatography using hexane/ethyl acetate (1:1 100% EA, v/v) to afforded 2H-[1,2′-bipyridin]-2-one in 50−90% yield. 10992

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry

N-(2-oxo-1,5,6,7,8-Pentaphenyl-1,2-dihydroquinolin-3-yl)-N(phenylsulfonyl)benzenesulfonamide (3j). White amorphous solid, Yield (78.5 mg, 96%): 1H NMR (400 MHz, CDCl3) δ 8.26 (dd, J = 4.8, 1.8 Hz, 1H), 8.07 (d, J = 7.9 Hz, 2H), 7.89 (d, J = 7.7 Hz, 2H), 7.60−7.55 (m, 2H), 7.45 (t, J = 7.8 Hz, 3H), 7.37−7.22 (m, 4H), 7.21−6.96 (m, 5H), 6.96−6.83 (m, 3H), 6.83−6.71 (m, 8H), 6.69− 6.62 (m, 2H), 6.41 (q, J = 7.7 Hz, 2H), 6.01 (d, J = 7.6 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 160.8, 153.1, 148.0, 146.9, 143.8, 140.8, 139.7, 139.2, 139.1, 138.5, 137.8, 137.1, 136.6, 133.9, 133.9, 132.1, 131.3, 131.2, 130.8, 130.7, 130.2, 129.2, 129.1, 129.1, 128.9, 128.8, 127.9, 128.0, 127.51, 127.4, 126.9, 126.8, 126.84, 126.78, 126.74, 126.59, 126.56, 126.54, 126.52, 126.48, 125.9, 125.8, 125.7, 124.6, 122.5, 119.7. FT-IR ν̃ = (KBr, cm−1) 3055, 2956, 1678, 1552, 1496, 1446, 1380, 1170; HRMS (ESI-TOF) Calculated for [M + H]+: C51H37N2O5S2, exact mass 821.2138, found 821.2142. 5,6,7,8-Tetraphenyl-1-(pyridin-2-yl)-3-(trifluoromethyl)quinolin2(1H)-one (3k). White amorphous solid, Yield (45.7 mg, 77%): 1H NMR (400 MHz, CDCl3) δ 8.26 (d, J = 5.0 Hz, 1H), 8.04 (s, 1H), 7.33 (d, J = 4.3 Hz, 2H), 7.25−7.11 (m, 3H), 7.05−6.97 (m, 3H), 6.91−6.85 (m, 2H), 6.82−6.71 (m, 8H), 6.70−6.61 (m, 2H), 6.49− 6.34 (m, 2H), 6.00 (d, J = 7.8 Hz, 1H). 13C NMR (150 MHz, CDCl3) δ 171.2, 159.5, 152.7, 148.3, 147.5, 141.3, 140.3, 139.7 (q, J = 5.4 Hz), 139.0, 138.9, 138.3, 138.0, 137.1, 136.4, 131.9, 131.3, 131.1, 131.0, 130.9, 130.8, 130.6, 130.6, 130.1, 128.1, 128.0, 127.9, 127.7, 127.6, 127.0, 126.8, 126.8, 126.6, 126.5, 126.0, 125.9, 125.8, 122.6, 122.3 (q, J = 273.2 Hz), 118.8 ; 19F NMR (376 MHz, CDCl3) δ −65.64.FT-IR ν̃ = (KBr, cm−1) 3058, 2927, 1683, 1557, 1508, 1416, 1376, 1293; HRMS (ESI-TOF) Calculated for [M + Na]+: C39H25F3N2NaO, exact mass 617.1811, found617.1817. 2-oxo-5,6,7,8-Tetraphenyl-1-(pyridin-2-yl)-1,2-dihydroquinoline3-carbonitrile (3l). Bright yellow amorphous solid, Yield (38 mg, 69%): 1H NMR (400 MHz, CDCl3) δ 8.27 (d, J = 4.6 Hz, 1H), 8.14 (s, 1H), 7.35 (dt, J = 12.5, 7.6 Hz, 2H), 7.23 (dt, J = 22.0, 6.3 Hz, 3H), 7.00 (d, J = 11.9 Hz, 3H), 6.95−6.90 (m, 1H), 6.88 (d, J = 7.3 Hz, 1H), 6.86−6.65 (m, 9H), 6.63 (d, J = 7.7 Hz, 1H), 6.43 (t, J = 7.7 Hz, 1H), 6.38 (d, J = 7.7 Hz, 1H), 5.99 (d, J = 7.8 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 160.1, 152.5, 148.7, 148.4, 141.2, 140.5, 138.7, 138.6, 138.4, 138.0, 136.7, 136.7, 131.9, 131.4, 131.0, 130.7, 130.5, 130.0, 128.2, 128.2, 127.9, 127.7, 127.6, 127.1, 126.9, 126.9, 126.7, 126.6, 126.2, 126.1, 126.0, 122.8, 119.6, 115.2, 106.7; FT-IR ν̃ = (KBr, cm−1) 3058, 2927, 2232, 1672, 1598, 1548, 1410, 1322, 1232; HRMS (ESITOF) Calculated for [M + H]+: C39H26N3O, exact mass 552.2070, found 552.2077. 4-Methyl-5,6,7,8-tetraphenyl-1-(pyridin-2-yl)quinolin-2(1H)-one (3m). White amorphous solid, Yield (36.6 mg, 68%):1H NMR (400 MHz, CDCl3) δ 8.35−8.20 (m, 1H), 7.36 (d, J = 7.6 Hz, 1H), 7.23 (t, J = 7.4 Hz, 1H), 7.17−7.11 (m, 2H), 7.08−6.94 (m, 4H), 6.91−6.55 (m, 12H), 6.51 (s, 1H), 6.38 (q, J = 7.7 Hz, 2H), 5.90 (d, J = 7.8 Hz, 1H), 1.74 (s, 3H). 13C NMR (150 MHz, CDCl3) δ 163.0, 153.8, 150.4, 148.0, 143.8, 141.3, 140.3, 139.7, 139.7, 139.5, 139.1, 138.2, 136.13, 132.0, 131.6, 131.3, 131.0, 130.6, 130.3, 127.8, 127.5, 127.4, 127.2, 127.1, 126.8, 126.6, 126.5, 126.4, 125.6, 125.4, 125.3, 123.5, 122.2, 121.8, 25.1; FT-IR ν̃ = (KBr, cm−1) 3054, 2925, 1672, 1586, 1537, 1491, 1443, 1394, 1262; HRMS (ESI-TOF) Calculated for [M + H]+: C39H29N2O, exact mass 541.2274: found: 541.2273. 4-(Benzyloxy)-5,6,7,8-tetraphenyl-1-(pyridin-2-yl)quinolin-2(1H)one (3n). White amorphous solid, Yield (55 mg, 87%): 1H NMR (400 MHz, CDCl3) δ 8.25 (d, J = 5.1 Hz, 1H), 7.25−7.11 (m, 5H), 7.04 (q, J = 7.4 Hz, 2H), 6.98−6.87 (m, 3H), 6.87−6.62 (m, 14H), 6.54 (d, J = 7.1 Hz, 1H), 6.45−6.25 (m, 2H), 6.03 (s, 1H), 5.91 (d, J = 7.7 Hz, 1H), 4.73 (d, J = 4.2 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ 164.9, 153.9, 147.9, 144.9, 141.8, 141.0, 140.3, 139.8, 139.6, 139.5, 138.6, 138.1, 136.1, 134.4, 132.8, 132.0, 131.4, 131.2, 131.1, 130.9, 130.6, 130.2, 129.4, 129.3, 128.4, 128.2, 128.1, 128.1, 126.5, 126.4, 126.3, 125.7, 125.6, 125.4, 125.2, 121.8, 117.0, 71.1; FT-IR ν̃ = (KBr, cm−1) 3056, 2928, 1660, 1544, 1496, 1428, 1364, 1222; HRMS (ESI-TOF) Calculated for [M + H]+: C45H33N2O2, exact mass 633.2537, found 633.2352. 1,2,3,4-Tetraphenyl-5-(pyridin-2-yl)phenanthridin-6(5H)-one (3o). White amorphous solid, Yield (23.6 mg, 41%): 1H NMR (400

[D1]-1e) in 0.1 mmol scale. Both the reactions were stopped after 3 h and product 3e was isolated separately by flash silica gel column chromatography. The reactions were repeated two times. On the basis of the isolated yields, KIE values were calculated as 1.78, and 1.73. So the average kH/kD was 1.75. Analytical Data. 5,6,7,8-Tetraphenyl-1-(pyridin-2-yl)quinolin2(1H)-one (3e). White amorphous solid, Yield (48.5 mg, 92%):1H NMR (400 MHz, CDCl3) δ 8.27 (dd, J = 4.9, 1.9 Hz, 1H), 7.62 (d, J = 9.9 Hz, 1H), 7.33 (dd, J = 14.4, 7.4 Hz, 2H), 7.24−7.07 (m, 3H), 7.07−6.92 (m, 3H), 6.87 (dd, J = 7.5, 4.9 Hz, 2H), 6.83−6.70 (m, 8H), 6.65 (d, J = 7.4 Hz, 2H), 6.60 (d, J = 9.9 Hz, 1H), 6.42 (q, J = 7.8 Hz, 2H), 6.04 (d, J = 7.7 Hz, 1H). 13C NMR (150 MHz, CDCl3) δ 163.9, 153.6, 148.3, 145.0, 139.9, 139.7, 139.6, 139.5, 139.2, 139.1, 138.2, 137.2, 136.3, 132.1, 131.5, 131.3, 131.0, 130.9, 130.7, 130.4, 127.9, 127.8, 127.5, 127.2, 126.8, 126.7, 126.7, 126.6, 126.4, 125.7, 125.6, 125.6, 122.2, 121.3, 120.9; FT-IR ν̃ = (KBr, cm−1) 3054, 2924, 1669, 1601, 1549, 1492, 1407, 1278; HRMS (ESI-TOF) Calculated for [M + H]+: C38H27N2O, exact mass 527.2118, found 527.2125. 3-Methyl-5,6,7,8-tetraphenyl-1-(pyridin-2-yl)quinolin-2(1H)-one (3f). White amorphous solid, Yield (46.5 mg, 86%): 1H NMR (400 MHz, CDCl3) δ 8.27 (dd, J = 4.8, 1.9 Hz, 1H), 7.48 (s, 1H), 7.41− 7.29 (m, 2H), 7.24−7.09 (m, 3H), 7.01 (dd, J = 13.9, 7.0 Hz, 3H), 6.86 (dt, J = 9.4, 4.8 Hz, 2H), 6.82−6.71 (m, 8H), 6.65 (d, J = 6.9 Hz, 2H), 6.50−6.36 (m, 2H), 6.05 (d, J = 7.7 Hz, 1H), 2.14 (s, 3H). 13C NMR (150 MHz, CDCl3) δ 164.5, 153.9, 148.2, 143.7, 139.8, 139.6, 139.2, 138.7, 138.5, 138.2, 137.0, 136.3, 136.1, 132.1, 131.5, 131.3, 131.1, 130.9, 130.8, 130.5, 130.3, 129.6, 127.9, 127.8, 127.7, 127.4, 126.9, 126.7, 126.6, 126.5, 126.5, 126.3, 125.6, 125.5, 125.4, 122.1, 120.9, 17.5; FT-IR ν = (KBr, cm−1) 3056, 2920, 1654, 1589, 1551, 1492, 1411, 1269; HRMS (ESI-TOF) Calculated for [M + H]+: C39H29N2O, exact mass 541.2274, found 541.2277. 5,6,7,8-Tetraphenyl-1-(pyridin-2-yl)-3-(trimethylsilyl)quinolin2(1H)-one (3g). White amorphous solid, Yield (55 mg, 92%):1H NMR (400 MHz, CDCl3) δ 8.26 (d, J = 4.7 Hz, 1H), 7.74 (s, 1H), 7.40− 7.28 (m, 2H), 7.21−7.14 (m, 3H), 7.04−6.94 (m, 3H), 6.92−6.69 (m, 10H), 6.65 (d, J = 7.7 Hz, 2H), 6.42 (q, J = 8.0 Hz, 2H), 6.05 (d, J = 7.7 Hz, 1H), 0.15 (s, 9H). 13C NMR (100 MHz, CDCl3) δ 166.0, 154.0, 148.4, 146.7, 144.9, 139.8, 139.7, 139.6, 139.5, 139.1, 138.2, 136.8, 136.2, 133.5, 132.2, 131.5, 131.3, 131.0, 130.9, 130.8, 130.5, 130.3, 127.9, 127.7, 127.6, 127.4, 127.1, 126.8, 126.7, 126.6, 126.5, 126.3, 125.6, 125.5, 125.5, 122.0, 120.9, −1.6; FT-IR ν = (KBr, cm−1) 3052, 2952, 1644, 1592, 1494, 1406, 1365, 1261; HRMS (ESI-TOF) Calculated for [M + H]+: C41H35N2OSi, exact mass 599.2513, found 599.2512. 3-(Benzyloxy)-5,6,7,8-tetraphenyl-1-(pyridin-2-yl)quinolin-2(1H)one (3h). White amorphous solid, Yield (48.7 mg, 77%): 1H NMR (400 MHz, CDCl3) δ 8.26 (d, J = 4.3 Hz, 1H), 7.27 (q, J = 3.0 Hz, 4H), 7.23−7.15 (m, 6H), 7.01−6.96 (m, 2H), 6.93−6.81 (m, 5H), 6.79−6.70 (m, 7H), 6.63 (q, J = 7.4 Hz, 2H), 6.47−6.31 (m, 2H), 6.02 (d, J = 7.7 Hz, 1H), 5.00 (s, 2H). 13C NMR (150 MHz, CDCl3) δ 159.9, 153.5, 148.2, 146.2, 142.1, 139.9, 139.6, 139.2, 138.7, 138.1, 137.2, 136.3, 135.9, 134.6, 132.1, 131.2, 130.8, 130.8, 130.6, 130.3, 128.7, 128.1, 128.0, 127.9, 127.8, 127.7, 127.4, 126.9, 126.8, 126.6, 126.6, 126.5, 126.3, 125.6, 125.5, 125.4, 122.3, 120.8, 114.1, 70.7. FTIR ν = (KBr, cm−1) 3066, 2928, 1659, 1659, 1560, 1509, 1459, 1365, 1268; HRMS (ESI-TOF) Calculated for [M + H]+: C45H33N2O2, exact mass 633.2537, found 633.2536. 3,5,6,7,8-Pentaphenyl-1-(pyridin-2-yl)quinolin-2(1H)-one (3i). White amorphous solid, Yield (53 mg, 88%): 1H NMR (400 MHz, CDCl3) δ 8.30 (d, J = 5.1 Hz, 1H), 7.81 (s, 1H), 7.60 (d, J = 7.5 Hz, 2H), 7.44−7.27 (m, 5H), 7.22−6.97 (m, 6H), 6.92−6.61 (m, 12H), 6.44 (d, J = 8.3 Hz, 2H), 6.08 (d, J = 7.9 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 163.2, 153.9, 148.2, 144.7, 139.8, 139.6, 139.5, 139.0, 138.7, 138.2, 137.3, 137.2, 136.3, 136.1, 132.1, 131.6, 131.4, 131.3, 131.2, 131.0, 130.9, 130.8, 130.4, 130.3, 129.1, 128.1, 128.07, 127.9, 127.8, 127.5, 127.1, 126.8, 126.7, 126.6, 126.5, 126.4, 125.7, 125.6, 125.5, 122.2, 121.1; FT-IR ν̃ = (KBr, cm−1) 3056, 2924, 1658, 1552, 1494, 1414, 1328, 1274; HRMS (ESI-TOF) Calculated for [M + H]+: C44H31N2O, exact mass 603.2431, found 603.2437. 10993

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry MHz, CDCl3) δ 8.44 (d, J = 7.9 Hz, 1H), 8.28 (d, J = 5.2 Hz, 1H), 7.42−7.29 (m, 2H), 7.21−6.96 (m, 9H), 6.91−6.61 (m, 12H), 6.48− 6.31 (m, 2H), 5.90 (m, 1H). 13C NMR (100 MHz, CDCl3) δ 163.44, 154.5, 147.9, 142.9, 141.8, 139.9, 139.8, 139.6, 138.2, 138.2, 138.1, 136.1, 135.2, 131.7, 131.5, 131.5, 129.1, 128.6, 128.0, 127.7, 127.4, 126.9, 126.8, 126.6, 126.5, 125.6, 125.4, 125.3, 121.7, 120.4; FT-IR ν̃ = (KBr, cm−1) 3056, 2928, 1668, 1600, 1496, 1440, 1384, 1286; HRMS (ESI-TOF) Calculated for [M + H]+: C42H29N2O, exact mass 577.2274, found 577.2280. 5,6,7,8-Tetraphenyl-1-(pyridin-2-yl)quinolin-4(1H)-one (3p). White amorphous solid, Yield (37.8 mg, 72%) 1H NMR (600 MHz, CDCl3) δ 8.18 (dd, J = 4.9, 1.9 Hz, 1H), 7.63 (d, J = 7.7 Hz, 1H), 7.37 (td, J = 7.7, 1.9 Hz, 1H), 7.15−7.00 (m, 5H), 6.92 (dd, J = 7.4, 4.9 Hz, 1H), 6.84 (d, J = 8.0 Hz, 1H), 6.82−6.68 (m, 12H), 6.64−6.54 (m, 3H), 6.18 (d, J = 7.7 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 178.9, 157.0, 148.9, 144.5, 143.6, 141.6, 141.1, 141.0, 140.2, 139.2, 139.1, 138.9, 138.5, 132.3, 132.1, 131.3, 130.5, 130.3, 129.5, 127.2, 126.9, 126.6, 126.5, 126.2, 125.8, 125.6, 125.5, 122.3, 121.4, 114.5, 113.4, 112.0. FT-IR ν̃ = (KBr, cm−1) 3054, 2924, 1666, 1601, 1549, 1492, 1407, 1278; HRMS (ESI-TOF) Calculated for [M + H]+: C38H27N2O, exact mass 527.2118, found 527.2130. 1,2,3,4-Tetraphenyl-10-(pyridin-2-yl)acridin-9(10H)-one (3q). White amorphous solid, Yield (37.4 mg, 65%): 1H NMR (400 MHz, CDCl3) δ 8.34 (d, J = 8.1 Hz, 1H), 8.25 (d, J = 4.7 Hz, 1H), 7.40 (t, J = 7.9 Hz, 1H), 7.33 (t, J = 7.8 Hz, 1H), 7.16 (d, J = 4.8 Hz, 5H), 7.10 (t, J = 8.0 Hz, 2H), 7.03−6.94 (m, 1H), 6.86 (t, J = 7.4 Hz, 1H), 6.82−6.76 (m, 6H), 6.75−6.67 (m, 5H), 6.60−6.55 (m, 2H), 6.52 (d, J = 7.5 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ 179.1, 163.5, 156.2, 149.3, 147.5, 144.0, 143.4, 142.2, 141.6, 139.9, 139.6, 139.4, 138.3, 137.4, 137.1, 133.2, 132.2, 131.5, 131.4, 130.5, 129.4, 127.9, 127.4, 127.1, 126.5, 126.4, 125.7, 125.6, 125.5, 125.4, 124.0, 122.4, 122.4, 122.2, 116.8 ; FT-IR ν̃ = (KBr, cm−1) 3056, 2929, 1655, 1603, 1543, 1509, 1457, 1421, 1268; HRMS (ESI-TOF) Calculated for [M + H]+: C42H29N2O, exact mass 577.2274, found 577.2269. 5,6,7,8-Tetraphenyl-1-(pyrimidin-2-yl)quinolin-4(1H)-one (3r). White amorphous solid, Yield (47 mg, 89%): 1H NMR (400 MHz, CDCl3) δ 8.36 (d, J = 4.8 Hz, 2H), 8.10 (d, J = 7.9 Hz, 1H), 7.15−7.05 (m, 5H), 6.88−6.73 (m, 12H), 6.71−6.69 (m, 2H), 6.65−6.56 (m, 2H), 6.20 (d, J = 8.0 Hz, 1H). 13C NMR (150 MHz, CDCl3) δ 179.3, 161.5, 159.0, 145.9, 142.5, 141.4, 141.2, 140.6, 139.7, 139.4, 139.3, 138.3, 132.7, 132.5, 131.3, 130.7, 129.5, 127.1, 126.9, 126.7, 126.6, 126.4, 126.0, 125.8, 125.7, 125.5, 118.1, 113.2; FT-IR ν̃ = (KBr, cm−1) 3055, 2924, 1638, 1562, 1498, 1441, 1406, 1294; HRMS (ESI-TOF) Calculated for [M + H]+: C37H26N3O, exact mass 528.2070, found 528.2064. 1-(Pyridin-2-yl)-5,6,7,8-tetrap-tolylquinolin-2(1H)-one (4a). White amorphous solid, Yield (53.5 mg, 92%):1H NMR (600 MHz, CDCl3) δ 8.24 (d, J = 4.2 Hz, 1H), 7.60 (d, J = 9.9 Hz, 1H), 7.22−7.14 (m, 2H), 7.10 (d, J = 7.8 Hz, 1H), 6.94 (d, J = 7.8 Hz, 1H), 6.90−6.83 (m, 3H), 6.80−6.76 (m, 3H), 6.67 (s, 2H), 6.64−6.50 (m, 4H), 6.47 (d, J = 8.0 Hz, 1H), 6.28 (d, J = 7.8 Hz, 1H), 6.21 (d, J = 7.8 Hz, 1H), 5.88 (d, J = 7.9 Hz, 1H), 2.28 (s, 3H), 2.10 (s, 3H), 2.05 (s, 3H), 2.01 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 164.03, 153.9, 148.1, 145.3, 140.1, 139.9, 139.6, 139.4, 137.4, 136.8, 136.6, 136.5, 136.3, 135.9, 135.5, 135.0, 134.7, 134.7, 132.0, 131.4, 131.1, 130.8, 130.6, 130.3, 128.8, 128.6, 128.4, 128.3, 127.8, 127.5, 127.2, 127.2, 127.1, 121.9, 121.0, 120.9, 21.4, 21.2, 21.1; FT-IR ν̃ = (KBr, cm−1) 3055, 2924, 1658, 1562, 1498, 1441, 1406, 1294; HRMS (ESI-TOF) Calculated for [M + H]+: C42H35N2O, exact mass 583.2744, found 583.2746. 5,6,7,8-Tetrakis(4-chlorophenyl)-1-(pyridin-2-yl)quinolin-2(1H)one (4b). White amorphous solid, Yield (55 mg, 83%): 1H NMR (400 MHz, CDCl3) δ 8.20 (d, J = 5.0 Hz, 1H), 7.47 (d, J = 9.9 Hz, 1H), 7.37−7.22 (m, 2H), 7.19−7.11 (m, 2H), 6.98−6.73 (m, 8H), 6.68 (d, J = 7.5 Hz, 1H), 6.63 (d, J = 7.8 Hz, 1H), 6.56 (d, J = 9.9 Hz, 2H), 6.48 (d, J = 8.3 Hz, 1H), 6.40 (d, J = 8.2 Hz, 1H), 6.25 (d, J = 8.4 Hz, 1H), 5.88 (d, J = 8.4 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 163.5, 153.4, 148.4, 143.5, 139.7, 139.1, 138.9, 137.4, 137.2, 137.0, 136.6, 136.1, 135.9, 133.8, 133.1, 132.5, 132.3, 132.3, 132.2, 132.0, 131.8, 131.5, 129.9, 128.6, 128.5, 128.0, 127.8, 127.7, 127.4, 127.3, 127.2, 122.6, 122.2, 121.2; FT-IR ν̃ = (KBr, cm−1) 3061, 2924, 1672, 1593, 1564,

1477, 1430, 1396, 1279; HRMS (ESI-TOF) Calculated for [M + H]+: C38H2335Cl4N2O, exact mass 663.0559, found 663.0552. 5,6,7,8-Tetrakis(4-bromophenyl)-1-(pyridin-2-yl)quinolin-2(1H)one (4c). White amorphous solid, Yield (67 mg, 80%): 1H NMR (600 MHz, CDCl3) δ 8.26 (dd, J = 4.9, 1.9 Hz, 1H), 7.51 (d, J = 9.9 Hz, 1H), 7.48 (d, J = 8.1 Hz, 1H), 6.59−6.54 (m, 1H), 7.34 (dt, J = 7.8, 3.8 Hz, 2H), 7.17 (d, J = 8.0 Hz, 2H), 7.07 (d, J = 8.2 Hz, 1H), 7.03−6.92 (m, 3H), 6.93−6.77 (m, 4H), 6.65−6.61 (m, 3H), 6.57 (d, J = 7.4 Hz, 1H), 6.48 (d, J = 8.3 Hz, 1H), 6.26 (d, J = 7.7 Hz, 1H), 5.87 (d, J = 7.7 Hz, 1H). 13C NMR (150 MHz, CDCl3) δ 163.5, 153.3, 148.4, 143.2, 139.6, 139.1, 138.8, 137.7, 137.6, 137.3, 136.7, 136.4, 135.7, 133.4, 132.8, 132.5, 132.5, 132.3, 132.2, 132.1, 131.8, 131.5, 131.4, 131.0, 130.6, 130.6, 130.4, 130.2, 130.1, 129.8, 127.8, 122.6, 122.2, 121.1, 120.6, 120.6; FT-IR ν̃ = (KBr, cm−1) 3056, 2924, 1662, 1595, 1494, 1432, 1372, 1280; HRMS (ESI-TOF) Calculated for [M + H]+: C38H2379Br4N2O, exact mass 838.8538, found 838.8537. 5,6,7,8-Tetrakis(4-fluorophenyl)-1-(pyridin-2-yl)quinolin-2(1H)one (4d). White amorphous solid, Yield (37.6 mg, 63%): 1H NMR (400 MHz, CDCl3) δ 8.28 (d, J = 5.0 Hz, 1H), 7.56 (d, J = 9.9 Hz, 1H), 7.36−7.20 (m, 2H), 7.09−6.81 (m, 6H), 6.62 (tdd, J = 31.4, 12.2, 5.9 Hz, 8H), 6.48−6.39 (m, 1H), 6.39−6.30 (m, 1H), 6.23−6.11 (m, 1H), 6.00 (t, J = 6.9 Hz, 1H). 13C NMR (101 MHz,CDCl3) δ 163.46, 161.7 (d, J = 247 Hz), 160.9 (d, J = 245 Hz), 160.8 (d, J = 245), 160.7 (d, J = 245 Hz), 153.4, 148.3, 144.1, 139.5, 139.2, 139.0, 136.4, 135.1 (d, J = 3.1 Hz), 134.9 (d, J = 3.3 Hz), 134.6 (d, J = 3.4 Hz), 133.6 (d, J = 3.2 Hz), 133.5 (d, J = 7.3 Hz), 132.7 (d, J = 7.5 Hz), 132.4 (d, J = 7.9 Hz), 132.3, 132.2, 132.1, 131.9 (d, J = 8.3 Hz), 131.6 (d, J = 8.2 Hz), 130.0, 127.6, 122.4, 121.8, 121.1, 115.2 (d, J = 8.8 Hz), 115.0 (d, J = 9.2 Hz), 114.8, 114.5, 114.2, 114.0, 113.9, 113.9, 113.8, 113.7, 113.7; 19 F NMR (376 MHz, Chloroform-d) δ −114.17, −115.52, −115.82, −115.89. FT-IR ν̃ = (KBr, cm−1) 3048, 2928, 1655, 1626, 1543, 1457, 1413, 1286, 1232; HRMS (ESI-TOF) Calculated for [M + H]+: C38H23F4N2O, exact mass 599.1741, found 599.1744. 5,6,7,8-Tetrakis(4-tert-butylphenyl)-1-(pyridin-2-yl)quinolin2(1H)-one (4e). White amorphous solid, Yield (47.2 mg, 63%): 1H NMR (400 MHz, CDCl3) δ 8.24 (d, J = 4.6 Hz, 1H), 7.75 (d, J = 9.8 Hz, 1H), 7.35−7.20 (m, 2H), 7.20−7.03 (m, 2H), 6.97−6.71 (m, 8H), 6.67−6.47 (m, 5H), 6.47−6.34 (m, 1H), 6.30−6.20 (m, 1H), 6.07− 5.75 (m, 1H), 1.25 (s, 9H), 1.13 (s, 9H), 1.06 (s, 9H), 1.01 (s, 9H). 13 C NMR (100 MHz, CDCl3) δ 164.1, 153.8, 149.7, 148.3, 148.2, 147.9, 145.6, 140.3, 139.8, 139.0, 137.6, 136.8, 136.7, 136.2, 136.0, 135.4, 132.1, 131.3, 130.9, 130.8, 130.7, 130.6, 130.4, 130.1, 128.1, 124.6, 124.4, 124.3, 123.3, 123.0, 122.8, 122.0, 120.8, 120.7, 34.6, 34.2, 34.2, 34.1, 31.4, 31.3, 31.2, 31.2; FT-IR ν̃ = (KBr, cm−1) 3070, 2930, 1666, 1604, 1512, 1418, 1362, 1228, 1156; HRMS (ESI-TOF) Calculated for [M + H]+: C54H59N2O, exact mass 751.4622, found 751.4624. 1-(Pyridin-2-yl)-5,6,7,8-tetrakis(4-(trifluoromethyl)phenyl)quinolin-2(1H)-one (4f). White amorphous solid, Yield (70 mg, 88%): 1 H NMR (600 MHz, CDCl3) δ 8.27 (dd, J = 5.0, 1.8 Hz, 1H), 7.60 (d, J = 8.0 Hz, 1H), 7.52 (d, J = 9.9 Hz, 1H), 7.48 (d, J = 7.9 Hz, 1H), 7.43 (d, J = 8.4 Hz, 1H), 7.27 (d, J = 8.1 Hz, 1H), 7.22 (td, J = 7.7, 1.9 Hz, 1H), 7.17 (t, J = 7.6 Hz, 2H), 6.93 (d, J = 7.7 Hz, 1H), 6.88 (d, J = 7.7 Hz, 1H), 6.78 (m, 7H), 6.64 (d, J = 9.8 Hz, 2H), 6.37 (d, J = 7.7 Hz, 1H), 6.19 (d, J = 8.1 Hz, 1H). 13C NMR (150 MHz,CDCl3) δ 163.5, 153.3, 148.5, 144.9, 142.9, 141.9, 139.1, 138.7, 138.6, 138.5, 137.3, 136.6, 131.74 (q, J = 5.3 Hz), 131.61 (q, J = 264 Hz), 131.63 (q, J = 265 Hz), 131.60 (q, J = 265 Hz), 131.2 (q, J = 4.9 Hz), 131.0, 130.8 (q, J = 5.9 Hz), 130.2, 129.8, 129.4, 128.2, 127.9, 127.2, 127.1, 126.9, 126.8, 126.2, 126.2, 124.9, 124.9, 124.8, 124.4, 124.2, 124.1, 123.6 (q, J = 7.2 Hz), 122.6, 122.1, 120.7; 19F NMR (376 MHz, CDCl3) δ −62.76, −62.87, −62.99; FT-IR ν̃ = (KBr, cm−1) 3056, 2932, 1667, 1608, 1512, 1418, 1288, 1248; HRMS (ESI-TOF) Calculated for [M + H]+: C42H23F12N2O, exact mass 799.1613, found 799.1611. 5,6,7,8-Tetrakis(3,5-bis(trifluoromethyl)phenyl)-1-(pyridin-2-yl)quinolin-2(1H)-one (4g). yellow oil, Yield (77 mg, 72%): 1H NMR (600 MHz, CDCl3) δ 8.30 (dd, J = 5.1, 1.9 Hz, 1H), 7.82 (s, 1H), 7.79 (d, J = 10.0 Hz, 1H), 7.59−7.49 (m, 2H), 7.46 (s, 2H), 7.39 (s, 1H), 7.36 (s, 1H), 7.34−7.26 (m, 3H), 7.11 (d, J = 6.2 Hz, 1H), 7.01−6.92 10994

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry (m, 2H), 6.84 (t, J = 10.6 Hz, 2H), 6.59 (s, 1H). 13C NMR (150 MHz, CDCl3) δ 162.5, 152.2, 149.2, 141.7, 139.8, 139.6, 139.6, 139.4, 138.6, 138.2, 137.5, 137.2, 134.2, 132.7, 132.5, 132.2 (q, J = 4.2 Hz), 131.9, 131.7, 131.6 (d, J = 8.3 Hz), 131.5 (d, J = 4.3 Hz), 131.4 (q, J = 4.4 Hz), 131.2 (q, J = 4.5 Hz), 131.1, 131.0 (q, J = 6.5 Hz), 130.7 (q, J = 3.6 Hz), 130.5, 130.5, 130.4, 130.4, 130.4, 130.4, 130.1, 130.0, 129.95, 129.93 (q, J = 4.9 Hz), 128.8, 127.4, 124.8, 124.6, 124.1, 123.8, 123.6 (q, J = 4.5 Hz), 123.3 (q, J = 6.6 Hz), 122.4, 122.37, 122.34, 121.82, 121.81, 121.4, 121.0 (q, J = 3.9 Hz), 120.84, 120.82, 120.61, 120.6; 19F NMR (376 MHz, CDCl3) δ −62.99, −63.09, −63.29, −63.38, −63.50, −63.89, −63.94. FT-IR ν̃ = (KBr, cm−1) 3057, 2923, 1671, 1590, 1544, 1489, 1431, 1378, 1275; HRMS (ESI-TOF) Calculated for [M + H]+: C46H19F24N2O, exact mass 1071.1109, found 1071.1115. 5,6,7,8-Tetra(naphthalen-1-yl)-1-(pyridin-2-yl)quinolin-2(1H)-one (4h). Light yellow amorphous solid, Yield (42.1 mg, 59%): 1H NMR (400 MHz, CDCl3) δ 8.38 (d, J = 6.3 Hz, 1H), δ 7.96 (d, J = 8.7 Hz, 1H), 7.84 (m, 2H), 7.78−7.69 (m, 2H), 7.68−7.56 (m, 5H), 7.56− 7.25 (m, 13H), 7.22−7.11 (m, 3H), 7.08−6.96 (m, 2H), 6.96−6.82 (m, 2H), 6.77 (m, 7.1 Hz, 1H), 6.52 (dd, J = 9.6, 4.4 Hz, 1H), 6.31 (d, J = 7.0 Hz, 1H). 13C NMR (150 MHz,CDCl3) δ 163.6, 152.2, 148.6, 140.6, 139.9, 138.4, 137.7, 136.9, 136.1, 134.6, 133.8, 133.3, 132.5, 130.4, 130.3, 130.1, 129.5, 129.4, 129.3, 128.9, 128.8, 128.6, 128.4, 128.2, 127.7, 127.7, 127.5, 127.5, 127.1, 126.9, 126.8, 126.6, 126.3, 126.1, 126.0, 125.9, 125.9, 125.8, 125.5, 125.5, 125.2, 124.9, 124.7, 124.6, 123.2, 122.5, 122.0, 120.5, 120.0: FT-IR ν̃ = (KBr, cm−1) 3046, 2924, 1671, 1592, 1543, 1509, 1459, 1380; HRMS (ESI-TOF) Calculated for [M + H]+: C54H35N2O, exact mass 727.2744, found 727.2729. 1-(Pyridin-2-yl)-5,6,7,8-tetra(thiophen-2-yl)quinolin-2(1H)-one (4i). Light yellow amorphous solid, Yield (46.2 mg, 84%): 1H NMR (600 MHz, CDCl3) δ 8.31 (dd, J = 5.0, 1.9 Hz, 1H), 7.78 (d, J = 9.9 Hz, 1H), 7.40 (m, 1H), 7.33 (m, 1H), 7.05−6.96 (m, 7H), 6.67 (d, J = 9.9 Hz, 1H), 6.65−6.61 (m, 1H), 6.56 (t, J = 4.4 Hz, 1H), 6.52 (d, J = 3.5 Hz, 1H), 6.41 (m, 1H), 6.28 (m, 1H), 5.66 (m, 1H). 13C NMR (150 MHz, CDCl3) δ 163.4, 153.4, 148.2, 141.4, 140.7, 139.7, 139.5, 139.2, 138.2, 137.9, 136.6, 134.9, 132.9, 130.2, 129.9, 129.4, 128.8, 127.7, 127.4, 126.6, 126.3, 125.9, 125.7, 125.5, 124.7, 122.7, 122.4, 122.2; FT-IR ν̃ = (KBr, cm−1) 3072, 2922, 1667, 1589, 1557, 1465, 1931, 1267; HRMS (ESI-TOF) Calculated for [M + H] +: C30H19N2OS4, exact mass 551.0375, found 551.0383. 5,6,7,8-Tetrapropyl-1-(pyridin-2-yl)quinolin-2(1H)-one (4j). Yellow liquid, Yield (41%): 1H NMR (400 MHz, CDCl3) δ 8.50 (dd, J = 4.9, 1.9 Hz, 1H), 7.96 (d, J = 9.8 Hz, 1H), 7.88 (td, J = 7.7, 2.0 Hz, 1H), 7.70 (d, J = 7.8 Hz, 1H), 7.31 (dd, J = 7.4, 4.9 Hz, 1H), 6.59 (d, J = 9.8 Hz, 1H), 2.89−2.73 (m, 2H), 2.57 (m, 4H), 1.68−1.46 (m, 6H), 1.46−1.37 (m, 2H), 1.09 (m, 8H), 0.99 (t, J = 7.3 Hz, 3H), 0.57 (t, J = 7.2 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 163.7, 154.5, 149.1, 143.9, 138.6, 138.4, 137.3, 136.0, 135.3, 128.2, 125.3, 122.8, 119.8, 119.6, 33.1, 32.5, 31.7, 30.8, 25.4, 24.83, 24.8, 23.6, 15.1, 14.9, 13.9; FT-IR ν̃ = (KBr, cm−1) 2958, 2930, 2870, 1666, 1560, 1464, 1312; HRMS (ESI-TOF) Calculated for [M + H]+: C26H35N2O: 391.2744, found 391.2746. 5,6,7,8-Tetraethyl-1-(pyridin-2-yl)quinolin-2(1H)-one (4k). Yellow liquid, Yield (34%): 1H NMR (400 MHz, CDCl3) δ 8.52 (m, 1H), 8.01 (d, J = 9.8 Hz, 1H), 7.88 (td, J = 7.8, 1.9 Hz, 1H), 7.75 (d, J = 8.0 Hz, 1H), 7.30 (dd, J = 7.4, 4.8 Hz, 1H), 6.61 (d, J = 9.8 Hz, 1H), 2.94 (q, J = 7.6 Hz, 2H), 2.70 (m, 4H), 1.33−1.24 (m, 5H), 1.20 (t, J = 7.5 Hz, 3H), 1.10 (t, J = 7.5 Hz, 3H), 0.68 (t, J = 7.3 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 163.9, 154.7, 149.1, 145.0, 138.7, 138.3, 137.3, 137.2, 136.2, 129.5, 125.5, 122.8, 119.8, 119.7, 23.4, 22.7, 21.9, 21.6, 16.2, 15.8, 15.7, 14.9; FT-IR ν̃ = (KBr, cm−1) 2968, 2930, 2871, 1664, 1562, 1430, 1298; HRMS (ESI-TOF) Calculated for [M + H]+: C22H27N2O: 335.2118, found 335.2119. 5,6,7,8-Tetraphenylquinolin-2(1H)-one (5). White amorphous solid, Yield (32.3 mg, 72%): 1H NMR (600 MHz, CDCl3) δ 8.57 (s, 1H), 7.62 (d, J = 9.9 Hz, 1H), 7.30 (dd, J = 8.1, 6.6 Hz, 2H), 7.25 (s, 1H), 7.25−7.21 (m, 2H), 7.21 (d, J = 7.0 Hz, 1H), 7.18−7.15 (m, 2H), 7.14−7.11 (m, 2H), 6.90−6.80 (m, 6H), 6.78 (m, 4H), 6.54 (dd, J = 9.8, 2.0 Hz, 1H); 13C NMR (150 MHz, CDCl3) δ 162.3, 143.7, 139.9, 139.7, 139.3, 139.2, 137.8, 136.2, 135.6, 134.6, 131.5, 130.9,

130.9, 130.8, 129.2, 128.3, 127.9, 127.4, 127.2, 127.0, 126.9, 126.1, 125.8, 121.5, 118.1; FT-IR ν̃ = (KBr, cm−1) 3364, 3056, 1666, 1580, 1496, 1440, 1384, 1294; HRMS (ESI-TOF) Calculated for [M + H]+: C33H24NO, exact mass 450.1852, found 450.1851.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.7b01932. 1 H, 13C, 19F NMR spectra for all new compounds and photophysical studies of quinolone derivatives (PDF)

■

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Rajarshi Samanta: 0000-0002-7925-6601 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by the SERB, India (YSS/2014/ 000383). Fellowships received from the Council of Scientific and Industrial Research (CSIR), India (A.B. and D.D.) and IIT Kharagpur (D.G.) are gratefully acknowledged.

■

REFERENCES

(1) (a) Salinas, Y.; Manez, R. M.; Marcos, M. D.; Sancenon, F.; Costero, A. M.; Parra, M.; Gil, S. Chem. Soc. Rev. 2012, 41, 1261. (b) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998, 120, 11864. (2) (a) Yamaguchi, J.; Yamaguchi, A. D.; Itami, K. Angew. Chem., Int. Ed. 2012, 51, 8960. (b) Kuhl, N.; Hopkinson, M. N.; Wencel-Delord, J.; Glorius, F. Angew. Chem., Int. Ed. 2012, 51, 10236. (c) Sarkar, S. D.; Liu, W.; Kozhushkov, S. I.; Ackermann, L. Adv. Synth. Catal. 2014, 356, 1461. (3) (a) Bras, J. L.; Muzart, J. Synthesis 2014, 46, 1555. (b) Yasukawa, T.; Satoh, T.; Miura, M.; Nomura, M. J. Am. Chem. Soc. 2002, 124, 12680. (c) Ueura, K.; Satoh, T.; Miura, M. J. Org. Chem. 2007, 72, 5362. (d) Yamashita, M.; Hirano, K.; Satoh, T.; Miura, M. Org. Lett. 2009, 11, 2337. (e) Yamashita, M.; Horiguchi, H.; Hirano, K.; Satoh, T.; Miura, M. J. Org. Chem. 2009, 74, 7481. (f) Uto, T.; Shimizu, M.; Ueura, K.; Tsurugi, H.; Satoh, T.; Miura, M. J. Org. Chem. 2008, 73, 298. (g) Fukutani, T.; Hirano, K.; Satoh, T.; Miura, M. J. Org. Chem. 2011, 76, 2867. (h) Ilies, L.; Matsumoto, A.; Kobayashi, M.; Yoshikai, N.; Nakamura, E. Synlett 2012, 23, 2381. (i) Adak, L.; Yoshikai, N. Tetrahedron 2012, 68, 5167. (4) Recent reviews: (a) Segawa, Y.; Maekawa, T.; Itami, K. Angew. Chem., Int. Ed. 2015, 54, 66. (b) Gulías, M.; Mascareñas, J. L. Angew. Chem., Int. Ed. 2016, 55, 11000 Rhodium catalyzed annulation:. (c) Yang, Y.; Li, K.; Cheng, Y.; Wan, D.; Li, M.; You, J. Chem. Commun. 2016, 52, 2872 Few recent papers:. (d) Zhang, S.-S.; Liu, X.G.; Chen, S.-Y.; Tan, D.-H.; Jiang, C.-Y.; Wu, J.-Q.; Li, Q.; Wang, H. Adv. Synth. Catal. 2016, 358, 1705. (e) Lao, Y.-X.; Zhang, S.-S.; Liu, X.G.; Jiang, C.-Y.; Wu, J.-Q.; Li, Q.; Huang, Z.-S.; Wang, H. Adv. Synth. Catal. 2016, 358, 2186. (f) Prakash, S.; Muralirajan, K.; Cheng, C.-H. Angew. Chem., Int. Ed. 2016, 55, 1844. (5) Wu, Y. − T.; Huang, K. − H.; Shin, C. − C.; Wu, T. − C. Chem. Eur. J. 2008, 14, 6697. (6) Pham, M. V.; Cramer, N. Angew. Chem., Int. Ed. 2014, 53, 3484. (7) Kim, O. S.; Jang, J. H.; Kim, H. T.; Han, S. J.; Tsui, G. C.; Joo, J. M. Org. Lett. 2017, 19, 1450. (8) (a) Umeda, N.; Tsurugi, H.; Satoh, T.; Miura, M. Angew. Chem., Int. Ed. 2008, 47, 4019. (b) Umeda, N.; Hirano, K.; Satoh, T.; Shibata, 10995

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996

Article

The Journal of Organic Chemistry N.; Sato, H.; Miura, M. J. Org. Chem. 2011, 76, 13. (c) Zheng, J.; You, S.-L. Chem. Commun. 2014, 50, 8204. (9) (a) Miura, M. Chem. - Asian J. 2010, 5, 847. (b) Song, G.; Gong, X.; Li, X. J. Org. Chem. 2011, 76, 7583. (c) Shi, Z.; Tang, C.; Jiao, N. Adv. Synth. Catal. 2012, 354, 2695. (d) Qian, Z.-C.; Zhou, J.; Li, B.; Shi, B.-F. Synlett 2014, 25, 1036. (e) Martinez, A. M.; Echa-varren, J.; Alonso, I.; Rodriguez, N.; Gomez Arrayas, R.; Carretero, J. C. Chem. Sci. 2015, 6, 5802. (f) Wu, J.; Cui, X.; Mi, X.; Li, Y.; Wu, Y. Chem. Commun. 2010, 46, 6771. (g) Wang, L.; Huang, J.; Peng, S.; Liu, H.; Jiang, X.; Wang, J. Angew. Chem., Int. Ed. 2013, 52, 1768. (10) (a) Fukuzumi, K.; Unoh, Y.; Nishii, Y.; Satoh, T.; Hirano, K.; Miura, M. J. Org. Chem. 2016, 81, 2474. (b) Li, X.; Yang, X.; Qi, Z. ACS Catal. 2016, 6, 6372. (c) Villar, J. M.; Suárez, J.; Varela, J. A.; Saá, C. Org. Lett. 2017, 19, 1702. (d) Morioka, R.; Nobushige, K.; Satoh, T.; Hirano, K.; Miura, M. Org. Lett. 2015, 17, 3130. (e) Ge, Q.; Hu, Y.; Li, B.; Wang, B. Org. Lett. 2016, 18, 2483. (f) Boldt, S.; Parpart, S.; Villinger, A.; Ehlers, P.; Langer, P. Angew. Chem., Int. Ed. 2017, 56, 4575. (11) Misal Castro, L. C.; Obata, A.; Aihara, Y.; Chatani, N. Chem. Eur. J. 2016, 22, 1362. (12) (a) Martínez, Á . M.; Echavarren, J.; Alonso, I.; Rodríguez, N.; Arrayás, R. G.; Carretero, J. C. Chem. Sci. 2015, 6, 5802. (b) Hyster, T. K.; Rovis, T. Chem. Commun. 2011, 47, 11846. (c) Schroder, N.; Lied, F.; Glorius, F. J. Am. Chem. Soc. 2015, 137, 1448. (13) (a) Cui, S. − F.; Addla, D.; Zhou, C. − H. J. Med. Chem. 2016, 59, 4488. (b) Cui, S. − F.; Peng, L. − P.; Zhang, H. − Z.; Rasheed, S.; Kumar, K. V.; Zhou, C. − H. Eur. J. Med. Chem. 2014, 86, 318. (c) Heeb, S.; Fletcher, M. P.; Chhabra, S. R.; Diggle, S. P.; Williams, P.; Cámara, M. FEMS Microbiol Rev. 2011, 35, 247. (14) (a) Nakatani, A.; Hirano, K.; Satoh, T.; Miura, M. Chem. - Eur. J. 2013, 19, 7691. (b) Nakatani, A.; Hirano, K.; Satoh, T.; Miura, M. J. Org. Chem. 2014, 79, 1377. (c) Modak, A.; Rana, S.; Maiti, D. J. Org. Chem. 2015, 80, 296. (d) Anagnostaki, E. E.; Fotiadou, A. D.; Demertzidou, V.; Zografos, A. L. Chem. Commun. 2014, 50, 6879. (e) Min, M.; Kim, Y.; Hong, S. Chem. Commun. 2013, 49, 196. (f) Cheng, D.; Gallagher, T. Org. Lett. 2009, 11, 2639. (g) Shi, Z.; Zhang, B.; Cui, Y.; Jiao, N. Angew. Chem., Int. Ed. 2010, 49, 4036. (h) Dutta, U.; Deb, A.; Lupton, D. W.; Maiti, D. Chem. Commun. 2015, 51, 17744. (15) Miura, W.; Hirano, K.; Miura, M. Synthesis 2017, DOI: 10.1055/ s-0036-1588735. (16) (a) Nakao, Y.; Idei, H.; Kanyiva, K. S.; Hiyama, T. J. Am. Chem. Soc. 2009, 131, 15996. (b) Tamura, R.; Yamada, Y.; Nakao, Y.; Hiyama, T. Angew. Chem. 2012, 124, 5777. (c) Donets, P. A.; Cramer, N. Angew. Chem., Int. Ed. 2015, 54, 633. (d) Das, D.; Biswas, A.; Karmakar, U.; Chand, S.; Samanta, R. J. Org. Chem. 2016, 81, 842. (e) Peng, P.; Wang, J.; Jiang, H.; Liu, H. Org. Lett. 2016, 18, 5376. (f) Li, T.; Wang, Z.; Xu, K.; Liu, W.; Zhang, X.; Mao, W.; Guo, Y.; Ge, X.; Pan, F. Org. Lett. 2016, 18, 1064. (g) Li, Y.; Xie, F.; Li, X. J. Org. Chem. 2016, 81, 715. (h) Das, D.; Poddar, P.; Maity, S.; Samanta, R. J. Org. Chem. 2017, 82, 3612. (i) Li, J.; Yang, Y.; Wang, Z.; Feng, B.; You, J. Org. Lett. 2017, 19, 3083. (j) Kumar, K. A.; Kannaboina, P.; Das, P. Org. Biomol. Chem. 2017, 15, 5457. (17) Smout, V.; Peschiulli, A.; Verbeeck, S.; Mitchell, E. A.; Herrebout, W.; Bultinck, P.; Vande Velde, C. M. L.; Berthelot, D.; Meerpoel, L.; Maes, B. U. W. J. Org. Chem. 2013, 78, 9803. (18) (a) Germain, M. E.; Knapp, M. J. Chem. Soc. Rev. 2009, 38, 2543. (b) Toal, S. J.; Trogler, W. C. For small molecule based NAC chemosensors, see. J. Mater. Chem. 2006, 16, 2871. (c) Shanmugaraju, S.; Mukherjee, P. S. Chem. Commun. 2015, 51, 16014 and references cited therein. (d) Chowdhury, A.; Mukherjee, P. S. J. Org. Chem. 2015, 80, 4064. (e) Kumar, S.; Venkatramaiah, N.; Patil, S. J. Phys. Chem. C 2013, 117, 7236. (f) Venkatramaiah, N.; Firmino, A. D. G.; Almeida Paz, F. A.; Tome, J. P. C. Chem. Commun. 2014, 50, 9683. (g) Chandrasekaran, Y.; Venkatramaiah, N.; Patil, S. Chem. - Eur. J. 2016, 22, 5288. (19) (a) Akhavan, J. The Chemistry of Explosives; RSC: Cornwall, U.K., 2004. (b) Czarnik, A. W. Nature 1998, 394, 417. (20) Sughara, M.; Ukita, T. Chem. Pharm. Bull. 1997, 45, 719.

(21) Chuentragoola, P.; Vongnamb, K.; Rashatasakhona, P.; Sukwattanasinitta, M.; Wacharasindhu, S. Tetrahedron 2011, 67, 8177. (22) Smout, V.; Peschiulli, A.; Verbeeck, S.; Mitchell, E. A.; Herrebout, W.; Bultinck, P.; Vande Velde, C. M. L.; Berthelot, D.; Meerpoel, L.; Maes, B. U. W. J. Org. Chem. 2013, 78, 9803.

10996

DOI: 10.1021/acs.joc.7b01932 J. Org. Chem. 2017, 82, 10989−10996