Stable Core-Modified Doubly N-Fused Expanded

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Stable Core-Modified Doubly N-Fused Expanded Dibenziporphyrinoids Sunit Kumar, Malakalapalli Rajeswara Rao, and Mangalampalli Ravikanth J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b02851 • Publication Date (Web): 03 Jan 2018 Downloaded from http://pubs.acs.org on January 3, 2018

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The Journal of Organic Chemistry

Stable Core-Modified Doubly N-Fused Expanded Dibenziporphyrinoids Sunit Kumar,a M. Rajeswara Raob and Mangalampalli Ravikanth*a a

Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India, Fax:91-22-5723480; Tel: 91-22-5767176 b

Indian Institute of Technology Dharwad, Dharwad, 580011, Karnataka, India

Abstract:

We described one pot synthesis of stable doubly N-fused expanded

dibenziporphyrinoids using readily available precursors under acid catalyzed conditions. The doubly N-fused expanded dibenziporphyrinoids have been synthesized by adopting inversion followed by fusion strategy. The studies showed that the dibenziporphyrinoids undergo mono fusion initially but due to high stability of doubly fused dibenziporphyrinoids, the mono-fused macrocycles undergo further fusion to form doubly fused dibenziporphyrinoids. The mono fusion and double fusion in these dibenziporphyrinoids were established by X-ray crystallography.

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Carbaporphyrinoids1 are macrocycles containing one or more carbon atoms along with other donor heteroatoms such as N, S, O, Se etc. inside the core and have been explored as a favourite porphyrin based ligand to synthesize organometallic complexes.2 Carbaporphyrinoids exist as fully aromatic species as well as nonaromatic and anti-aromatic compounds. The presence of carbocyclic rings along with heterocycles in carbaporphyrinoid macrocyclic skeleton alters the electronic properties significantly which are quite different from porphyrinoids. The pioneering works carried out by the research groups of Lash,1, 2 Latos-Grażyński,3 Furuta,4 and others5 have established that carbaporphyrinoids are the most promising macrocycles with multitude of applications that range from catalysis to material science and medicine. Benziporphyrinoids6 containing one or two benzene rings along with other fivemembered heterocycles are the most widely studied carbaporphyrinoids and known to exhibit intriguing spectroscopic, structural and coordinating properties. Interestingly, the expanded porphyrinoids7 containing more than four five-membered heterocycles have been extensively investigated over the years but relatively few examples are available on expanded benziporphyrinoids although the first example was reported in 1991.8 Another feature which is not yet studied to a greater extent in expanded benziporphyrinoid9 is the chemistry of inversion of heterocyclic unit which is well-established in expanded porphyrinoids.10 Many expanded porphyrinoids known in literature exhibit the inversion of heterocycle ring such as pyrrole, thiophene, furan, selenophene etc.10 The inversion of heterocycle ring in porphyrinoids may sometimes result in the formation of

another very interesting macrocycle called N-fused

porphyrinoid which contains an unique fused tripentacyclic (TP) ring in the macrocyclic core due to the formation of a bond between pyrrole N with that of α- or β-carbon of neighbouring inverted pentacycle.11 However, such a fusion to result tripentacyclic rings is not common and


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very few examples are available in literature.11 Furuta and co-workers reported the first examples of N-fused porphyrin12 1 and N-fused sapphyrin13 and other related macrocycles containing tripentacyclic rings. These fused macrocycles were synthesized from the appropriate N-confused porphyrinoid systems but not from the inverted porphyrinoids.12, 13 Furthermore, Furuta and coworkers14 have also reported the synthesis of N-fused pentaphyrin 2 which was obtained during the condensation reactions under mild acid-catalysed conditions. The formation of N-fused pentaphyrin 2 was attributed to the pyrrole inversion followed by fusion during the condensation reaction. These N-fused porphyrinoids were used as ligands to prepare metal complexes and studied their properties.15

Figure 1: Structures dibenziporphyrinoids

of

N-fused

porphyrin,

pentaphyrin,

benzipentaphyrin

and

Latos-Grażyński and co-workers16 isolated an unique N-fused benzipentaphyrin 3 by adopting similar pyrrole inversion followed by fusion strategy. Subsequently, Furuta and coworkers also succeeded in synthesizing doubly fused porphyrin17 4 and pentaphyrin18 from corresponding N-confused N-fused porphyrin and N-confused N-fused pentaphyrin respectively (Figure 1). Thus, a perusal of literature revealed that singly fused porphyrinoinds were formed via inversion strategy followed by fusion, but no examples on doubly fused porphyriniods under this simple strategy. Herein, we report the first examples of doubly N-fused core-modified



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expanded dibenziporphyrins 5a-5d which were synthesized in one pot reaction via inversion followed by fusion strategy. These novel macrocycles contain two N-fused tripentacyclic rings because of formation of bond between nitrogens of two pyrrole rings with neighbouring βcarbons of inverted thiophene rings. However, our initial aim was to synthesize core-modified expanded dibenziporphyrin 6 but serendipitously, we obtained the doubly fused expanded dibenziporphyrin 5a as confirmed by X-ray crystallography (vide-infra).

To establish our

serendipitous discovery, we varied different diols and tripyrranes and synthesized three other doubly fused expanded dibenziporphyrins 5b-5d. The macrocycles 5a-5d were highly stable in solid and in solution state and characterized by HR-MS, 1D, 2D NMR spectroscopy and X-ray crystallography. The target macrocycles 5a-5d were prepared by following [5+3] condensation method as shown in Scheme 1. The (10,10′-bis[(p-tolyl/anisyl/4-isopropylbenzene/4-tert-butylbenzene) hydroxymethyl]-1,3-bis(2-thienyl)benzenediol) diols 7a-7d were synthesized in 45-63% yields by treating 1,3-bis(2-thienyl)benzene with 2.5 equivalents of n-BuLi followed by 2.5 equivalents of appropriate aryl aldehyde in THF at 0° C and subsequent purification by silica gel column chromatography. The 5,20-bis(p-tolyl/anisyl/4-isopropylbenzene/4-tert-butyl benzene)27,28-bis(thia)-25,26-dihydrotripyrranes 8a-8d were prepared by treating appropriate diol 7a-7d with 10 equivalents of pyrrole under mild acid catalyzed conditions followed by silica gel column chromatographic purification.

The doubly N-fused expanded dibenziporphyrinoid 5a

was synthesized by condensing one equivalent of appropriate diol 7a with one equivalent of tripyrrane 8a in CH2Cl2 in presence of catalytic amount of TFA under inert atmosphere for 2h followed by oxidation with two equivalents of DDQ in open air for additional 2h (Scheme 1). TLC analysis showed distinctively one major polar spot and one less polar minor spot.


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However, upon addition of further two equivalents of DDQ followed by continuous stirring the reaction mixture for extra 2h in open air, we noticed that the major polar spot disappeared and the earlier minor spot had become the major spot. The crude compound was subjected to silica gel column chromatography and afforded the only macrocycle 5a as purple solution using pet ether/CH2Cl2. The macrocycle 5a was freely soluble in common organic solvents and it is stable in solution and in solid form. The single crystal of compound 5a was obtained readily from CH2Cl2/n-hexanes and the crystal structure showed that the macrocycle obtained was the unprecedented doubly N-fused dibenziporphyrinoid 5a. To test the generality of the reaction, we carried out the [5+3] condensation with three other different diols 7b-7d and three different tripyrranes 8b-8d under same mild acid catalyzed conditions followed by oxidation with four equivalents of DDQ and successfully obtained the doubly N-fused dibenziporphyrinoids 5b-5d in 10-15% yields. To know about the other intermediate macrocycle which initially formed in these reactions but transformed to the doubly fused macrocycle, we made an attempt to isolate and characterize the intermediate macrocycle. Thus, condensation of diol 7a and tripyrrane 8a was carried out under mild TFA catalyzed conditions for 2h and oxidized by only two equivalents of DDQ. Column chromatographic purification yielded the intermediate macrocycle 9.

Fortunately, we obtained the crystal structure of 9 and the structure revealed that the

macrocycle was mono N-fused dihydrobenziporphyrin 9 (vide infra). Thus, the [5+3] condensation initially results in the formation of the intermediate mono N-fused dihydrobenziporphyrin 9 which transforms to doubly N-fused dibenziporphyrin upon further oxidation. The doubly N-fused dibenziporphyrinoids 5a-5d, therefore can be obtained readily in one pot reaction under mild acid catalyzed reaction conditions.



Scheme 1: Synthesis of macrocycles 5a-5d. The single crystals of 5a were grown via slow evaporation of n-hexane into CH2Cl2 solution at room temperature over a period of 3 days. The molecule crystallizes with a triclinic crystal system with P-1 space group. The crystallographic data and crystal parameters are given in Table S1 while all the relevant bond distances are tabulated in Table S2 & S3 (see Supporting information). It is evident from the X-ray structure that the macrocycle 5a is highly ruffled and resembles a Mobius conformation (Figure 2). However, the 1,3-connection of dithienyl benzene provide no continuous π-delocalization leading to a non-aromatic system. Further, it renders unambiguous evidence towards the formation of two tripentacyclic (TP) rings in cis fashion. The sulphur atom of the fused thiophene rings were pointing outwards while those of the free thiophene rings were pointing inwards. The flexibility of the large core and the rigid TP rings induced a large distortion at the meso positions between the TP rings and thiophenes with dihedral angles of 53.7° and 57.1° which minimizes the π-delocalization pathway. Moreover, central benzenes exhibit asymmetric dihedral angles of 41.0° and 22.1° with respect to TP rings while the thiophenes on the non-fused side showcase 6.4° and 32.5°. The C-C bond lengths of the thiophenes in the TP rings match closely with those of the non-fused indicating that the aromaticity of the former thiophenes is unperturbed. Also, C-C bond lengths of the TP rings


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exhibit close to ~1.40 Å which is in line with the expected π-delocalization within the rings. The crystal structure of the intermediate mono N-fused dihydrobenziporphyrin 9 also possess highly contorted conformation with closely matching dihedral angles to that of 5a. However, the central benzene rings maintain near planarity (~3-5°) with their corresponding substituents (thiophenethiophene or thiophene-TP ring), which could be attributed to the increased flexibility bestowed by two sp3 carbons. Overall, it is anticipated that the relatively electron-rich and structurally rigid TP ring (vs thiophene) in the intermediate compound 9 may facilitate the fusion to occur on the same side of the macrocycle. However, the high selectivity of formation of cis-isomer over transisomer is unclear at present and more investigations are needed to understand the selective formation of cis-isomer.

Figure 2: Single crystal X-ray structure of macrocycles (a) 5a and (b) 9 at 50% probability. For clarity, all of the hydrogen atoms have been omitted. The macrocycles 5a-5d were further characterized by detailed 1D and 2D NMR spectroscopy and the representative 1D and 2D NMR spectra of 5a are shown in Figure 3 and Figure S1 (see Supporting information). All the resonances of the macrocycles 5a-5d were



identified based on position, integration, coupling constant and cross-peak correlations in 1D and 2D NMR spectra and the molecular structures of 5a-5d were deduced (see Supporting information). We have attempted to characterize the intermediate macrocycle 9 by NMR spectroscopy. The 1H NMR recorded for compound 9 at room temperature as well as at 233 K showed very complex spectrum with large number of resonances due to unsymmetric nature of macrocycle 9. Since we could not carry out detailed 2D NMR studies at low temperature because of our instrument limitation, the identification and assignment of all the resonances in 1H NMR spectrum of macrocycle 9 was not done.

Figure 3: 1H NMR spectra of macrocycle 5a recorded in CDCl3. The absorption and electrochemical properties were investigated for doubly N-fused dibenziporphyrinoids 5a-5d along with mono N-fused dihydrobenziporphyrinoid 9 and data are presented in Table S4 (see Supporting Information). The comparison of absorption spectra of 5a and 9 are presented in Figure 4a and the cyclic voltammograms are provided in Figure 4b. Both 5a and 9 showed typical non-aromatic absorption features with three broad absorption bands present in 300-700 nm region. Unlike the reported macrocycles where meso-aryl groups lie orthogonal to the plane of the macrocycles in order to avoid steric interactions, the TP rings of 5a-5d facilitate the meso-aryls to remain in the plane which led to the extended π-delocalization resulted in red-shifted absorption. The absorption bands of 5a were slightly bathochromically


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shifted compared to 9. These fused macrocycles 5a-5d exhibited two reversible oxidations at ~ 0.8 and 1.10 V and one irreversible reduction at ~ -1.20 V. The low oxidation potentials support that the macrocycles are electron rich.

Figure 4: (a) Comparison of absorption spectra of compound 9 (black line) and compound 5a (red line) recorded in a chloroform and (b) Comparison of cyclic voltammograms of compound 9 (black line), compound 5a (red line) and differential pulse voltammogram (blue line) recorded in CH2Cl2 with 0.1 M TBAP as the supporting electrolyte at a scan rate of 50 mVs-1.

CONCLUSIONS In summary, we have synthesized the first stable doubly N-fused non-aromatic expanded dibenziporphyrins in one pot under mild reaction conditions. We have demonstrated that the double fusion can be induced in the expanded dibenziporphyrin by adopting simple inversion strategy followed by fusion. The double fusion in expanded dibenziporphyrinoid occurs stepwise via the formation of an intermediate mono N-fused dihydrobenziporphyrin. Both mono Nfused dihydrobenziporphyrin and doubly N-fused dibenziporphyrin were structurally characterized which showed the presence of tripentacyclic ring(s) leading to the structural contortion in the macrocycles. The NMR and absorption studies supported the non-aromatic nature of the macrocycles while electrochemical studies revealed the electron rich behaviour of



these fused expanded dibenziporphyrinoids. Presently, the studies are underway to understand the underdeveloped inversion followed by fusion strategy to disclose the factors responsible for fusion in expanded carbaporphyrinoids.

MATERIALS AND METHODS General Experimental: The chemicals such as BF3·Et2O, TFA and 2, 3-dichloro-5, 6-dicyano1,4-benzoquinone (DDQ) were used as obtained from Aldrich. All other chemicals used for the synthesis were reagent grade unless otherwise specified. Column chromatography was performed on silica gel. The 1H NMR spectra were recorded in CDCl3 on Bruker 400 and 500 MHz instruments. The frequencies for 13C nucleus are 100.06 and 125.77 MHz for 400 MHz and 500 MHz instruments respectively. Tetramethylsilane [Si(CH3)4] was used as an internal standard for 1

H and 13C NMR. Absorption spectra were obtained with Agilent Technologies Cary 5000 UV-

Vis-NIR. Cyclic voltammetric (CV) studies were carried out with BAS electrochemical system utilizing the three electrode configuration consisting of a glassy carbon (working electrode), platinum wire (auxiliary electrode) and saturated calomel (reference electrode) electrodes. The experiments were done in dry dichloromethane using 0.1 M tetrabutylammonium perchlorate as supporting electrolyte. The HR mass spectra were recorded with a Q-TOF micro mass spectrometer. For UV-vis, the solution for all compounds (1×10-5 M) was prepared by using spectroscopic grade CHCl3 solvent. X-ray crystal structure analysis: Single-crystal X-ray structure analysis was performed on a Rigaku Saturn724 diffractometer that was equipped with a low-temperature attachment. Data were collected at 100 K using graphite-monochromated Mo-Kα radiation (λα= 0.71073 Å) by ωscan technique. The data were reduced by using CrystalClear-SM Ex-pert 2.1 b24 software. The


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structures were solved by direct methods and refined by least-squares against F2 utilizing the software packages SHELXL-97,19a,b SIR-92,19c and WINGX.19d All non-hydrogen atoms were refined anisotropically. CCDC No. 1564600, 1564601 (for 5a and 9) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Density functional calculations (see supporting information) of the molecular structures (in the gas phase) and the molecular orbital energies were carried out at the B3LYP/6-31G(d) level as implemented in Gaussian 09.20 (10,10′-bis[(p-toly/anisyl/4-isopropylbenzene/4-tertbutylbenzene)hydroxymethyl]-1,3-bis(2thienyl)benzenediol) diols 7a-7d: Dry and distilled n-hexane (30mL) was added to a 250-mL three-necked, round-bottom flask fitted with a rubber septum and gas inlet tube; the flask was flushed with nitrogen for 10 min. Tetramethylethylenediamine (TMEDA) (3.09 mL, 20.66 mmol) and n-butyllithium (12.91 mL of ca. 1.6 M solution in hexane) were added to the stirred solution and the reaction temperature was maintained at 0° C in an ice bath. 1,3-bis(2thienyl)benzene21 (2.00 g, 8.26 mmol) was added and the solution was refluxed gently for 1 h. As the reaction progressed, a white turbid solution formed indicating the formation of lithiated salt of 1,3-bis(2-thienyl)benzene. The reaction mixture was allowed to attain room temperature. To this reaction mixture, an ice cold solution of appropriate aryl aldehyde (20.66 mmol) in dry THF (40mL) was then added under ice bath and stirred for an additional 15 min at 0oC. The reaction mixture was brought to room temperature and stirred for additional 2h and quenched by adding an ice-cold NH4Cl solution (50 mL, ca. 1 M). The organic layer was diluted with ether and washed several times with water and brine and dried over anhydrous Na2SO4. The solvent was removed in a rotary evaporator under reduced pressure to afford the crude compound. TLC



analysis showed three spots corresponding to unchanged bithiabenzene, unreacted aldehyde and the desired di-ol. The crude compound was loaded on silica and eluted with petroleum ether. The 1,3-bis(2-thienyl)benzene and aldehyde were removed with petroleum ether/ethyl acetate (98:02) mixture and the desired diol 7a-7d was collected with petroleum ether/ethyl acetate (~70:30) mixture. The solvent was removed in a rotary evaporator to afford diols as a white solid in 4563% yield. 7a: (63% yield, 2.40 gm); 1H NMR (400 MHz, CDCl3, δ in ppm): δ = 7.69-7.70 (m, 1H, benzene), 7.41 (d, J = 7.8 Hz, 2H, benzene), 7.35 (d, J = 7.8 Hz, 4H, Ar), 7.31 (t, J = 7.5 Hz, 1H, benzene), 7.18 (d, J = 8.2 Hz, 4H, Ar), 7.15 (d, J = 3.6 Hz, 2H, thiophene), 6.85 (d, J = 3.6 Hz, 2H, thiophene), 6.01 (s, 2H, -CH), 2.36 (s, 6H, tolyl-CH3); 13C NMR (125 MHz, CDCl3, δ in ppm): δ = 148.2, 143.9, 140.2, 138.1, 135.1, 129.6, 129.5, 126.5, 125.9, 124.9, 123.2, 123.1, 72.7, 21.3 ppm; HRMS mass calcd. for C30H25OS2 (M-OH)+ 465.1341. found 465.1344. 7b: (45% yield, 1.80 gm); 1H NMR (500 MHz, CDCl3, δ in ppm): δ = 7.72-7.71 (m, 1H, benzene), 7.44 (d, J = 8.0 Hz, 2H, benzene), 7.39 (d, J = 9.0 Hz, 4H, Ar), 7.32 (t, J = 7.5 Hz, 1H, benzene), 7.16 (d, J = 4.0 Hz, 2H, thiophene), 6.91 (d, J = 9.00 Hz, 4H, Ar), 6.88 (d, J = 4.0 Hz, 2H, thiophene), 6.00 (s, 2H, -CH), 3.81 (s, 6H, anisyl-OCH3); 13C NMR (125 MHz, CDCl3, δ in ppm): δ = 159.6, 148.3, 143.8, 135.3, 135.1, 129.5, 127.8, 125.7, 124.9, 123.1, 123.0, 114.1, 72.4, 55.4 ppm; HRMS calcd. for C30H25O3S2 (M-OH)+ 497.1240. found 497.1230. 7c: (60% yield, 2.70 gm); 1H NMR (400 MHz, CDCl3, δ in ppm): δ = 7.72-7.71 (m, 1H, benzene), 7.43 (d, J = 6.4 Hz, 2H, benzene), 7.40 (d, J = 8.0 Hz, 4H, Ar), 7.31 (t, J = 7.6 Hz, 1H, benzene), 7.25 (d, J = 6.80 Hz, 4H, Ar), 7.15 (d, J = 3.6 Hz, 2H, thiophene), 6.85 (d, J = 3.6 Hz, 2H, thiophene), 6.00 (s, 2H, -CH), 2.92 (sep, J = 7.2 Hz, 2H, Iso-CH), 1.26 (d, J = 6.8 Hz, 12H, Iso-CH3); 13C NMR (100 MHz, CDCl3, δ in ppm): δ = 149.0, 148.1, 143.8, 140.5, 135.1,


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129.4, 126.8, 126.5, 125.8, 124.9, 123.1, 123.0, 72.7, 34.0, 24.1 ppm; HRMS mass calcd. for C34H33OS2 (M-OH)+ 521.1967. found 521.1960. 7d: (55% yield, 2.60 gm); 1H NMR (500 MHz, CDCl3, δ in ppm): δ = 7.69-7.70 (m, 1H, benzene), 7.40 (d, J = 7.5 Hz, 2H, benzene), 7.41 (bs, 8H, Ar), 7.32 (t, J = 7.5 Hz, 1H, benzene), 7.16 (d, J = 3.5 Hz, 2H, thiophene), 6.87 (d, J = 3.5 Hz, 2H, thiophene), 6.00 (s, 2H, -CH), 1.32 (s, 18H, tbu -CH3);

13

C NMR (125 MHz, CDCl3, δ in ppm): δ = 151.1, 147.9, 143.7, 139.9,

135.0, 129.3, 126.0, 125.6, 125.5, 124.8, 123.0, 122.9, 72.5, 34.6, 31.3 ppm; HRMS calcd. for C36H37OS2 (M-OH)+ 549.2280. found 549.2277. 5,20-bis(p-tolyl)-27,28-bis(thia)-25,26-dihydrotripyrrane (8a): To the solution of (10,10′bis[(p-tolyl)hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7a (1.00 g, 2.07 mmol) in pyrrole (1.40 mL, 20.07 mmol) taken in 100 mL round bottom flask, BF3.OEt2 (0.025 mL, 0.207 mmol) was added to initiate reaction. The reaction mixture was stirred under nitrogen for 30 min at room temperature. Then the mixture was diluted with dichloromethane (300 mL) and washed with 0.1 N aq. NaOH (100 mL), water (2 x 100 mL) and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure and the unreacted pyrrole was removed by vacuum distillation at room temperature. The compound was purified by silica gel column chromatography using petroleum ether/ethyl acetate (90:10). The evaporation of solvent on rotary evaporator under reduced pressure gave the desired compound 8a as orange oil in 75% yield (0.90 g); 1H NMR (500 MHz, CDCl3, δ in ppm): δ = 7.95 (bs, 1H, NH), 7.69-7.65 (m, 1H, benzene), 7.40 (d, J = 7.5 Hz, 2H, benzene), 7.30 (t, J = 8.0 Hz, 1H, benzene), 7.20-7.14 (m, 10H, Ar, thiophene), 6.77 (d, J = 3.5 Hz, 2H, thiophene), 6.73-6.72 (m, 2H, pyrrole), 6.18 (q, J = 5.5 Hz, 2H, pyrrole), 6.00-5.98 (m, 2H, pyrrole), 5.64 (s, 2H, -CH), 2.34 (s, 6H, tolyl-CH3); 13C NMR (125 MHz, CDCl3, δ in ppm): δ = 147.2, 143.1, 139.7, 137.0, 135.1, 133.2, 129.5, 129.4,



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128.4, 126.8, 124.6, 123.0, 122.8, 117.4, 108.5, 107.7, 45.8, 21.2 ppm; HRMS calcd. for C38H32NaN2S2 (M+K)+ 603.1899. found 603.1896. 5,20-bis(anisyl)-27,28-bis(thia)-25,26-dihydrotripyrrane

(8b):

5,20-bis(anisyl)-27,28-

bis(thia)-25,26-dihydrotripyrrane 8b was prepared by following the same procedure as given for compound 8a by using

(10,10′-bis[(anisyl)hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7b

(1.00 g, 1.94 mmol), pyrrole (1.30 mL, 19.45 mmol) and BF3.OEt2 (0.02 mL, 0.19 mmol). The crude compound was purified by silica column chromatography and obtained the desired compound 8b using petroleum ether/ethyl acetate (90:10) as orange oil in 65% yield (0.77 g). 1H NMR (400 MHz, CDCl3, δ in ppm): δ = 8.03 (bs, 1H, NH), 7.75-7.74 (m, 1H, benzene), 7.46 (d, J = 7.6 Hz, 2H, benzene), 7.32 (t, J = 7.4 Hz, 1H, benzene), 7.26 (d, J = 8.6 Hz, 2H, Αr), 7.20 (d, J = 3.6 Hz, 2H, thiophene), 6.90 (d, J = 8.6 Hz, 2H, Αr), 6.80 (d, J = 3.5 Hz, 2H, thiophene), 6.75-6.74 (m, 2H, pyrrole), 6.23 (q, J = 5.64 Hz, 2H, pyrrole), 6.04-6.03 (m, 2H, pyrrole), 5.63 (s, 2H, -CH), 3.83 (s, J = 7.2 Hz, 6H, anisyl-OCH3);

13

C NMR (100 MHz, CDCl3, δ in ppm): δ =

158.6, 147.4, 142.8, 135.0, 134.8, 133.2, 129.4, 129.3, 126.7, 124.5, 122.9, 122.5, 117.4, 114.0, 108.3, 107.5, 55.3, 45.2 ppm; HRMS calcd. for C38H33N2O2S2 (M+H)+ 613.1978. found 613.1982. 5,20-bis(4-isopropylbenzene)-27,28-bis(thia)-25,26-dihydrotripyrrane

(8c):

5,20-bis(4-

isopropylbenzene)-27,28-bis(thia)-25,26-dihydrotripyrrane 8c was prepared by following the same

procedure

as

given

for

compound

8a

by

using

(10,10′-bis[(4-

isopropylbenzene)hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7c (1.00 g, 1.85 mmol), pyrrole (1.30 mL, 18.58 mmol) and BF3.OEt2 (0.02 mL, 0.19 mmol). The crude compound was purified by silica gel column chromatography and obtained the desired compound 8c using petroleum ether/ ethyl acetate (90:10) as orange oil in 70% yield (0.82 g). 1H NMR (400 MHz, CDCl3, δ in


Page 15 of 22 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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


ppm): δ = 7.94 (bs, 1H, NH), 7.72-7.71 (m, 1H, benzene), 7.44 (d, J = 6.0 Hz, 2H, benzene), 7.31 (t, J = 7.2 Hz, 1H, benzene), 7.21-7.29 (m, 8H, Ar), 7.19 (d, J = 3.6 Hz, 2H, thiophene), 6.80 (d, J = 3.6 Hz, 2H, thiophene), 6.73-6.71 (m, 2H, pyrrole), 6.20 (q, J = 6.0 Hz, 2H, pyrrole), 6.04-5.64 (m, 2H, pyrrole), 5.64 (s, 2H, -CH), 2.93 (sep, J = 7.2 Hz, 2H, iso-CH), 1.28 (d, J = 7.2 Hz, 12H, iso-CH3); 13C NMR (100 MHz, CDCl3, δ in ppm): δ = 147.8, 147.2, 143.0, 140.0, 135.1, 133.1, 129.4, 128.4, 126.8, 124.6, 123.0, 122.8, 117.4, 108.5, 107.7, 45.8, 33.8, 24.1 ppm; HRMS calcd. for C42H40KN2S2 (M+K)+ 675.2264. found 675.2265. 5,20-bis(4-tertbutylbenzene)-27,28-bis(thia)-25,26-dihydrotripyrrane

(8d):

5,20-bis(4-

tertbutylbenzene)-27,28-bis(thia)-25,26-dihydrotripyrrane 8d was prepared by following the same

procedure

as

given

for

compound

8a

by

using

(10,10′-bis[(4-

tertbutylbenzene)hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7d (1.00 g, 1.76 mmol), pyrrole (1.20 mL, 17.66 mmol) and BF3.OEt2 (0.02 mL, 0.17 mmol). The crude compound was purified by silica column chromatography and obtained the desired compound 8d using petroleum ether/ ethyl acetate (90:10) as orange oil in 75% yield (0.88 g). 1H NMR (400 MHz, CDCl3, δ in ppm): δ = 7.93 (bs, 1H, NH), 7.68-7.69 (m, 1H, benzene), 7.41 (d, J = 7.2 Hz, 2H, benzene), 7.35 (d, J = 8.4 Hz, 4H, Ar), 7.29 (t, J = 8.0 Hz, 1H, benzene), 7.23 (d, J = 8.4 Hz, 4H, Ar), 7.16 (d, J = 3.6 Hz, 2H, thiophene), 6.79 (d, J = 3.6 Hz, 2H, thiophene), 6.72-6.70 (m, 2H, pyrrole), 6.17 (q, J = 5.8 Hz, 2H, pyrrole), 6.02-6.01 (m, 2H, pyrrole), 5.63 (s, 2H, -CH), 1.33 (s, 18H, tbu-CH3); 13C NMR (100 MHz, CDCl3, δ in ppm): δ = 150.1, 147.2, 143.0, 139.6, 135.1, 133.2, 129.4, 128.1, 136.8, 125.7, 124.6, 123.0, 122.8, 117.4, 108.5, 107.7, 45.8, 34.6, 31.5 ppm; HRMS calcd. for C44H45N2S2 (M+H)+ 665.3019. found 665.3000. Compound 5a: Samples of (10,10′-bis[(p-tolyl) hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7a (100 mg, 0.20 mmol) and one equivalent of appropriate 5,20-bis(p-tolyl)-27,28-bis(thia)-



25,26-dihydrotripyrrane 8a (120 mg, 0.20 mmol) in dichloromethane (100 mL) were condensed in the presence of TFA (8.00 µL, 0.10 mmol) for 1 h under inert atmosphere at room temperature. The reaction was then oxidized with four equivalents of DDQ (188 mg, 0.80 mmol) for 4 h in open air. The crude compound was purified by silica gel column chromatography using petroleum ether/ dichloromethane (70:30) to afford 5a as brown solid in 15 % yield (30 mg). 1H NMR (400 MHz, CDCl3, δ in ppm): 7.71 (bs, 2H, benzene), 7.59-7.55 (m, 6H, Ar, thiophene), 7.37-7.30 (m, 8H, Ar, benzene), 7.29-7.24 (m, 4H, Ar), 7.24-7.15 (m, 8H, Ar, benzene thiophene), 6.95 (d, J = 5.8 Hz, 2H, pyrrole), 6.45 (d, J = 5.8 Hz, 2H, pyrrole), 6.01 (s, 2H, inner thiophene), 2.40 (s, 6H, tolyl -CH3), 2.39 (s, 6H, tolyl -CH3); 13C NMR (125 MHz, CDCl3, δ in ppm): 147.1, 142.9, 142.0, 140.7, 139.2, 138.4, 138.2, 138.0, 136.2, 136.0, 134.0, 131.4, 131.2, 131.0, 129.8, 129.7, 129.1, 126.8, 126.2, 125.1, 124.3, 123.7, 123.4, 119.8, 118.3, 112.8, 109.8, 29.9, 21.5, 21.4; UV-vis (in CHCl3, λmax/nm, log ε) = 345 (4.91), 451 (4.51) and 537 (4.47); HRMS calcd. for C68H46N2S4[M]+ 1018.2538, Found 1018.2534. Compound 5b: The compound 5b was prepared by following the same procedure as given for compound 5a by using (10,10′-bis[(anisyl) hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7b (100 mg, 0.19 mmol), 5,20-bis(anisyl)-27,28-bis(thia)-25,26-dihydrotripyrrane 8b (119 mg, 0.19 mmol), TFA (7.00 µL, 0.09 mmol) and DDQ (176 mg, 0.77 mmol). The crude compound was purified by silica gel column chromatography using petroleum ether/ dichloromethane (60:40) to afford 5b as brown solid in 12 % yield (25 mg). 1H NMR (500 MHz, CDCl3, δ in ppm): 7.71(bs, 2H, benzene), 7.61-7.59 (m, 6H, Ar, thiophene), 7.40-7.35 (m, 6H, Ar, benzene), 7.26-7.19 (m, 6H, benzene, thiophene), 7.00 (d, J = 8.7 Hz, 4H, Ar), 6.95-6.91 (m, 6H, Ar, pyrrole),), 6.43 (d, J = 5.7 Hz, 2H, pyrrole), 6.02 (s, 2H, inner thiophene), 3.86 (bs, 12H, anisyl -OCH3); 13C NMR (125 MHz, CDCl3, δ in ppm): 159.9, 158.3, 147.12, 141.6, 140.4, 134.0, 133.4, 132.8, 131.2,


Page 16 of 22

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129.6, 127.4, 126.7, 126.6, 126.0, 125.1, 124.2, 123.7, 123.0, 117.8, 114.6, 113.9, 113.9, 112.3, 109.8, 55.5, 37.2, 29.8, 14.28; UV-vis (in CHCl3, λmax/nm, log ε) = 342 (4.97), 458 (4.54) and 543 (4.53); HRMS calcd. for C68H46N2O4S4[M]+ 1082.2335, Found 1082.2330. Compound 5c: The compound 5c was prepared by following the same procedure as given for compound

5a

thienyl)benzenediol

by

using

(10,10′-bis[(4-isopropylbenzene)hydroxymethyl]-1,3-bis(2-

7c (100 mg, 0.18 mmol), 5,20-bis(4-isopropylbenzene)-27,28-bis(thia)-

25,26-dihydrotripyrrane 8c (120 mg, 0.18 mmol), TFA (7.00 µL, 0.09 mmol) and DDQ (168 mg, 0.74 mmol). The crude compound was purified by silica gel column chromatography using petroleum ether/ dichloromethane (75:25) to afford 5c as brown solid in 10 % yield (22 mg). 1H NMR (500 MHz, CDCl3, δ in ppm): 7.62 (d, J = 8.1 Hz, 4H, Ar), 7.38 (d, J = 8.0 Hz, 4H, Ar), 7.32-7.31 (m, 8H, Ar, benzene), 7.29-7.22 (m, 8H, Ar, benzene, thiophene), 7.00 (d, J = 3.6 Hz, 2H, thiophene), 6.94 (d, J = 5.7 Hz, 2H, pyrrole), 6.44 (d, J = 5.7 Hz, 2H, pyrrole), 5.59 (s, 2H, inner thiophene), 2.98-2.90 (m, 4H, iso -CH), 1.30-1.28 (m, 24H, iso -CH3);

13

C NMR (125

MHz, CDCl3, δ in ppm): 149.2, 147.1, 145.5, 142.5, 141.4, 141.2, 139.0, 138.3, 137.9, 136.4, 134.6, 131.6, 131.5, 129.4, 127.2, 126.5, 126.4, 126.2, 125.7, 125.4, 125.1, 125.0, 123.8, 118.6, 112.6, 112.4, 111.5, 34.2, 34.1, 34.0, 24.1, 24.1, 24.0, 22.5, 14.2; UV-vis (in CHCl3, λmax/nm, log ε) = 338(4.92), 452(4.50) and 535(4.45); HRMS calcd. for C76H62N2S4[M]+ 1130.3790, Found 1130.3795. Compound 5d: The compound 5d was prepared by following the same procedure as given for compound

5a

thienyl)benzenediol

by

using

(10,10′-bis[(4-tertbutylbenzene)hydroxymethyl]-1,3-bis(2-

7d (100 mg, 0.17 mmol), 5,20-bis(4-tertbutylbenzene)-27,28-bis(thia)-

25,26-dihydrotripyrrane 8d (117 mg, 0.17 mmol), TFA (6.50 µL, 0.08 mmol) and DDQ (160 mg, 0.70 mmol). The crude compound was purified by silica gel column chromatography using



petroleum ether/dichloromethane (80:20) to afford 5d as brown solid in 14 % yield (30 mg). 1H NMR (400 MHz, CDCl3, δ in ppm): 7.62 (d, 4H, J = 8.4 Hz, Ar), 7.46 (d, J = 8.4 Hz, 8H, Ar), 7.45-7.35(m, 8H, Ar), 7.35-7.30 (m, 4H, benzene), 7.26-7.20 (m, 4H, benzene, thiophene), 7.17 (bs, 2H, benzene), 7.01 (d, J = 3.7 Hz, thaiophene), 6.96 (d, J = 5.1 Hz, 2H, pyrrole), 6.45 (d, J = 5.8 Hz, 2H, pyrrole), 5.60 (s, 2H, inner thiophene), 1.37 (s, 18H, tbu -CH3), 1.36 (s, 18H, tbu CH3); 13C NMR (125 MHz, CDCl3, δ in ppm): 149.4, 145.5, 142.5, 141.5, 141.3, 139.1, 138.0, 137.9, 138.0, 137.9, 136.4, 134.6, 131.5, 131.5, 131.2, 129.4, 128.9, 126.7, 126.6, 126.1, 126.0, 125.7, 125.4, 125.3, 125.1, 125.0, 123.8, 123.2, 118.5, 112.3, 111.5, 55.5, 34.5, 34.7, 31.5, 29.8, 22.8, 14.2; UV-vis (in CHCl3, λmax/nm, log ε) = 337 (4.93), 452 (4.50) and 536 (4.45); HRMS calcd. for C80H70N2S4[M]+ 1186.4416, Found 1186.4415. Compound 9: Sample of (10,10′-bis[(p-tolyl) hydroxymethyl]-1,3-bis(2-thienyl)benzenediol 7a (100 mg, 0.20 mmol) and 5,20-bis(p-tolyl)-27,28-bis(thia)-25,26-dihydrotripyrrane 8a (120 mg, 0.20 mmol) were dissolved in dichloromethane (100 mL) and TFA (8.00 µL, 0.10 mmol) was added to initiate the reaction. The reaction mixture was stirred in the dark at room temperature under nitrogen for 1 h. Two equivalents of DDQ (94 mg, 0.40 mmol) was added, and the mixture was stirred for further 2 h. The crude compound was purified by silica gel column chromatography using petroleum ether/ dichloromethane (60:40) to afford 9 as brown solid in 18 % yield (40 mg). 1H NMR (500 MHz, CDCl3, δ in ppm): 7.89 (bs, 2H), 7.68 (bs, 1H), 7.89 (d, J = 8.0 Hz, 2H), 7.47-7.38 (m, 4H), 7.30-7.09 (m, 17H), 6.94 (d, J = 5.8 Hz, 1H), 6.83 (m, 1H), 6.50 (bs, 1H), 6.40 (d, J = 5.7 Hz, 1H), 6.10-5.98 (m, 4H), 5.66-5.51 (m, 4H), 2.41 (s, 3H, tolyl CH3), 2.40 (s, 3H, tolyl -CH3), 2.35 (s, 3H, tolyl -CH3), 2.33 (s, 3H, tolyl -CH3); 13C NMR (125 MHz, CDCl3, δ in ppm): 147.3, 138.9, 138.5, 138.3, 138.0, 136.9, 136.8, 136.2, 135.8, 135.0, 134.4, 134.0, 131.6, 131.5, 131.1, 129.8, 129.4, 129.1, 128.4, 127.4, 126.3, 126.2, 125.3, 124.5,


Page 18 of 22

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124.1, 123.5, 123.2, 122.9, 121.6, 121.1, 118.4, 112.8, 55.5, 45.9, 32.1, 31.6, 30.3, 29.9, 29.8, 29.5, 27.0, 22.8, 21.5, 21.4, 21.2; UV-vis (in CHCl3, λmax/nm, log ε) = 308 (4.30), 460 (4.30) and 552 (4.27); HRMS calcd. for C68H51N2S4[M+H]+ 1023.2930, Found 1023.2933.

ASSOCIATED CONTENT Supporting Information: It contains characterization data (including HRMS, 1H, and

13

C

NMR spectra, Crystal data) for all the reported compounds, absorption, electrochemical and computational data.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. Fax: 91-22-5723480. Tel: 91-22-5767176. ORCID Mangalampalli Ravikanth: 0000-0003-0193-6081 Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS M.R. thanks the SERB Department of Science and Technology, Government of India (file no. EMR/2015/002196 to M.R.), and S.K. thanks the UGC for fellowship.

REFERENCES (1) a) Lash, T. D. Chem. Rev. 2017, 117, 2313-2446; b) Lash, T. D. Eur. J. Org. Chem. 2007, 5461-5481; c) Lash, T. D. Acc. Chem. Res. 2016, 49, 471-482. (2) Lash, T. D. Chem. – Asian. J. 2014, 9, 682−705. (3) Szyszko, B.; Latos-Grażyński, L. Chem. Soc. Rev. 2015, 44, 3588-3616.



(4) a) Srinivasan, A.; Furuta, H. Acc. Chem. Res. 2005, 38, 10-20; b) Toganoh, M.; Furuta, H. In Handbook of Porphyrin Science-With Applications to Chemistry, Physics, Material Science, Engineering, Biology and Medicine; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; World Scientific Publishing: Singapore, 2010, 2, 103-192. (5) a) Venkatraman, S.; Anand, V. G.; Pushpan, S. K.; Sankar, J.; Chandrashekar, T. K. Chem. Commun. 2002, 462-463; b) Saha, I.; Yoo, J.; Lee, J. H.; Hwang, H.; Lee, C.-H. Chem. Commun. 2015, 51, 16506-16509; c) Abebayehu, A.; Park, D.; Hwang, S.; Dutta, R.; Lee, C.-H. Dalton Trans. 2016, 45, 3093–3101. (6) Lash, T. D. Org. Biomol. Chem. 2015, 13, 7846-7878. (7) Saito, S.; Osuka, A. Angew. Chem. Int. Ed. 2011, 50, 4342-4373; b) Sessler, J. L.; Seidel, D. Angew. Chem. Int. Ed. 2003, 42, 5134-5175. (8) Corriu, R. J. P.; Bolin, G.; Moreau, J. J. E.; Vernhet, C. A. J. Chem. Soc., Chem. Commun. 1991, 27, 211−213. (9) Stepien, M.; Szyszko, B.; Latos-Grażyński, L. Org. Lett. 2009, 11, 3930–3933. (10) Szyszko, B.; Białek, M. J.; Pacholska-Dudziak, E.; Latos-Grażyński, L. Chem. Rev. 2017, 117, 2839−2909. (11) Toganoh, M.; Furuta, H. Chem. Commun. 2012, 48, 937-954. (12) a) Furuta, H.; Ishizuka, T.; Osuka, A.; Ogawa, T. J. Am. Chem. Soc. 1999, 121, 29452946; b) Furuta, H.; Ishizuka, T.; Osuka, A.; Ogawa, T. J. Am. Chem. Soc. 2000, 122, 5748-5757. (13) Gupta, I.; Srinivasan, A.; Morimoto, T.; Toganoh, M.; Furuta, H. Angew. Chem., Int. Ed. 2008, 47, 4563-4567. (14) Shin, J.-Y.; Furuta, H. Osuka, A. Angew. Chem., Int. Ed. 2001, 40, 619-621.


Page 20 of 22

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(15) a) Higashino, T.; Osuka, A. Chem. Sci. 2012, 3, 103-107; b) Ishida, S.-S.; Kim, J. O.; Kim, D.; Osuka, A. Chem. Eur. J. 2016, 22, 16554-16561; c) Ishida, S.-I.; Osuka, A. Chem. Asian J. 2015, 10, 2200–2206; d) Toganoh, M.; Matsuo, H.; Sato, A.; Furuta, H. Chem. -Eur. J. 2016, 22, 8316–8322. (16) Szyszko, B.; Sprutta, N.; Chwalisz, P.; Stepien, M.; Latos-Grażyński, L. Chem. – Eur. J. 2014, 20, 1985–1997. (17) Toganoh, M.; Kimura, T.; Uno, H.; Furuta, H. Angew. Chem., Int. Ed. 2008, 47, 89138916. (18) Srinivasan, A. Ishizuka, T.; Furuta, H. Angew. Chem., Int. Ed. 2004, 43, 876-879. (19) a) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112; b) Program for Crystal Structure Solution and Refinement; University of Göttingen: Göttingen, Germany, 1997; c) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Gualaridi, A. J. Appl. Crystallogr. 1993, 26, 343; d) Farrugia, L. J. Appl. Crystallogr. 1999, 32, 837. (20) Frisch, M. J. et al., Gaussian 09, Revision B.01, Gaussian, Inc., Wallingford CT, 2009. (21) Kumar. S.; Ravikanth, M. J. Org. Chem. 2017, 82,12359-12365.



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Page 22 of 22

Stable Core-Modified Doubly N-Fused Expanded

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