Efficient Synthesis of Trimethylsilyl-Substituted Dithieno[2,3-b:3′,2′-d]thiophene, Tetra[2,3-thienylene] and Hexa[2,3-thienylene] from Substituted [3,3′]Bithiophenyl

Abstract

Efficient synthetic procedures for the preparation of b-trithiophenes (dithieno[2,3-b:3′,2′-d]thiophene) and two macrocyclic compounds, tetra[2,3-thienylene] and hexa[2,3-thienylene] bearing trimethylsilyl (TMS) groups from 2,2′-dibromo-5,5′-bistrimethylsilanyl[3,3′]bithiophenyl are reported. The UV-Vis spectra property and crystal structures of these macrocyclic oligo­thiophenes are described.

bithiophenyl - cyclization - fused-ring system - hetero­cycles - macrocylces

References and Notes

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2 Handbook of Oligothiophenes and Polythiophenes   Fichou D. Wiley-VCH; Weinheim: 1999. 

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4b Sun Y. Ma Y. Liu Y. Lin Y. Wang Z. Wang Y. Xiao K. Chen X. Qiu W. Zhang B. Yu G. Hu W. Zhu D. Adv. Funct. Mater.  2006,  16:  426 

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From Dr. Rajca’s work:

8a Rajca A. Wang H. Pink M. Rajca S. Angew. Chem. Int. Ed.  2000,  39:  4481 ; Angew. Chem. 2000, 112, 4655

8b Rajca A. Miyasaka M. Pink M. Wang H. Rajca S. J. Am. Chem. Soc.  2004,  126:  15211 

8c Miyasaka M. Pink M. Rajca A. Rajca S. Chem. Eur. J.  2004,  10:  6531 

8d Miyasaka M. Rajca A. Synlett  2004,  177 

8e Miyasaka M. Rajca A. Pink M. Rajca S. J. Am. Chem. Soc.  2005,  127:  13806 

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10a Kabir SMH. Miura M. Sasaki S. Harada G. Kuwatani Y. Yoshida M. Iyoda M. Heterocycles  2000,  52:  761 

10b Miyasaka M. Rajca A. J. Org. Chem.  2006,  71:  3264 

11 Iyoda M. Miura M. Sasiki S. Kabir SMH. Kuwatani Y. Yoshida M. Tetrahedron Lett.  1997,  38:  4581 

12 Nenajdenko VG. Gribkov DV. Sumerin VV. Balenkova ES. Synthesis  2003,  124 

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14 Marsella MJ. Yoon K. Tham FS. Org. Lett.  2001,  3:  2129 

15

Compounds 6 and 7 were prepared according to the method from ref. 12.

16

Preparation of 8: n-BuLi (2.5 M in hexane, 15.0 mL, 37.5 mmol, 2.2 equiv) was added dropwise to diisopropylamine (5.5 mL, 38.9 mmol, 2.3 equiv) in Et₂O (30 mL) at 0 °C. After keeping at 0 °C for 0.5 h, the prepared LDA solution was transferred by syringe into a solution of 7 (5.44 g, 16.8 mmol) with anhyd Et₂O. After keeping at 0 °C for 2 h, the reaction mixture was cooled to -78 °C, then trimethyl-chlorosilane (10.8 mL, 85.1 mmol, 5.1 equiv) was added dropwise. The reaction mixture was kept at -78 °C for 1 h and then warmed slowly to r.t. overnight. After quenching with H₂O (50 mL), the crude product was extracted with Et₂O (3 × 40 mL) and washed with H₂O (50 mL), and then dried over MgSO₄. After removing the solvent in vacuo, the residue was purified by column chromatography on silica gel with PE (60-90 °C) as eluent to yield 8 (7.00 g, 89.1%) as a white solid. From two other reactions on a 4.44-g and 5.79-g scale of 7, 5.74 g (89.5%) and 7.39 g (88.4%) of 8 were obtained, respectively; mp 79-81 °C. ¹H NMR (400 MHz, CDCl₃): d = 7.15 (s, 2 H), 0.32 (s, 18 H). ¹³C NMR (100 MHz, CDCl₃): d = 141.7, 137.0, 136.0, 115.7, 0.0 [J(²⁹Si-¹³C) = 54 Hz]. MS (EI, 70 eV): m/z = 568 (14) [M⁺], 453 (67) [M⁺ - Me]. Anal. Calcd for C₁₄H₂₀Br₂S₂Si₂ (468.42): C, 35.90; H, 4.30; S, 13.69. Found: C, 35.33; H, 4.40; S, 13.46. IR (KBr): 3095, 3078, 2927, 2857 (CH) cm^-1.

17

Preparation of 9: To a solution of 8 (1.00 g, 2.13 mmol) in anhyd Et₂O (80 mL), t-BuLi (2.5 M, 3.9 mL, 4.6 equiv) was added dropwise at -78 °C. After keeping at -78 °C for 2 h, anhyd (PhSO₂)₂S (0.67 g, 2.13 mmol, 1.0 equiv) was added, then the reaction mixture was kept at -78 °C for 2 h and warmed slowly to r.t. overnight. The reaction mixture was quenched with H₂O (50 mL), extracted with Et₂O (2 × 40 mL) and then washed with H₂O (2 × 50 mL). After drying over MgSO₄, the solvent was removed in vacuo. The residue was purified by column chromatography on silica gel with PE (60-90 °C) as eluent to yield 9 (0.47 g, 64.8%) as a white solid. From two other reactions on a 1.00-g and 3.00-g scale of 8, using n-BuLi (2.3 equiv), 0.38 g (52.4%) and 1.10 g (51.0%) of 9 were obtained, respectively; mp 49-50 °C. ¹H NMR (400 MHz, CDCl₃): d = 7.47 (s, 2 H), 0.37 (s, 18 H). ¹³C NMR (100 MHz, CDCl₃): d = 144.5, 144.1, 139.8, 125.1, -0.3. MS (EI, 70 eV): m/z = 340 (77) [M⁺], 325 (100) [M⁺ - Me]. Anal. Calcd for C₁₄H₂₀S₃Si₂ (340.67): C, 49.36; H, 5.92; S, 28.24. Found: C, 49.30; H, 5.83; S, 27.74. IR (KBr): 2951, 2889 (CH) cm^-1.

18

Preparation of 1: To a solution of 9 (2.11 g, 6.19 mmol) in CHCl₃ (30 mL), TFA (2.0 mL) was added dropwise at r.t. The reaction progress was monitored by TLC analysis. After stirring at r.t. for 1 h, the reaction mixture was quenched with H₂O (10 mL), extracted with CHCl₃ (3 × 50 mL), and then washed with sat. NaHCO₃ (40 mL) and H₂O (2 × 40 mL). After drying over MgSO₄, the solvent was removed in vacuo. A white powder of 1 (1.20 g, 98.7%) was obtained. From another reaction on a 2.09-g scale of 9, 1.17 g (97.2%) of 1 was obtained; mp 84-85 °C (lit.^10b 86-87 °C). ¹H NMR (400 MHz, CDCl₃): d = 7.40 (d, J = 5.2 Hz, 2 H), 7.38 (d, J = 5.2 Hz, 2 H). ¹³C NMR (100 MHz, CDCl₃): d = 139.0, 138.3, 127.5, 118.8. MS (EI, 70 eV): m/z = 196 (100) [M⁺]. IR (KBr): 2955, 2894 (CH) cm^-1.

19

Preparation of 10 and 11: To a solution of 8 (2.00 g, 4.27 mmol) in anhyd Et₂O (60 mL), n-BuLi (2.5 M, 4.0 mL, 10.0 mmol, 2.3 equiv) was added dropwise at -78 °C. After keeping at -78 °C for 2 h, anhyd CuCl₂ (1.7 g, 12.6 mmol, 3.0 equiv) was added. The reaction mixture was kept at -78 °C for 2 h, and then slowly warmed to r.t. overnight. The reaction mixture was quenched with H₂O (50 mL), extracted with Et₂O (3 × 40 mL), washed with H₂O (50 mL), and then finally dried over MgSO₄. After removing the solvent in vacuo, the residue was purified by column chromatography on silica gel with PE (60-90 °C) as eluent to yield 10 (0.55 g, 41.5%) as a pale white crystal and 11 (0.40 g, 36.5%) as a white powder. For 10: mp 302 °C(sublimation). ¹H NMR (400 MHz, CDCl₃): d = 7.06 (s, 4 H), 0.32 (s, 36 H). ¹³C NMR (100 MHz, CDCl₃): d = 142.3, 137.7, 137.3, 136.8, 136.5, -0.2 [J(²⁹Si-¹³C) = 49 Hz]. HRMS (ESI): m/z [M + H]⁺ calcd for C₂₈H₄₁S₄Si₄: 617.1168; found: 617.1154. HRMS (ESI): m/z [M + Na]⁺ calcd for C₂₈H₄₀NaS₄Si₄: 639.0988; found: 639.0997. IR: 3160.2, 2954.9 (CH) cm^-1. For 11: mp 258-261 °C (wax), 286 °C (clear). ¹H NMR (400 MHz, CDCl₃): d = 7.17 (s, 2 H), 6.83 (s, 2 H), 6.44 (s, 2 H), 0.38 (s, 18 H), 0.28 (s, 18 H), 0.18 (s, 18 H). ¹³C NMR (100 MHz, CDCl₃): d = 140.0, 139.8, 139.5, 138.4, 138.1, 136.4, 136.0, 135.6, 134.8, 132.3, -0.1. HRMS (ESI): m/z [M + H]⁺ calcd for C₄₂H₆₁S₆Si₆: 925.1713; found: 925.1700. HRMS (ESI): m/z [M + Na]⁺ calcd for C₄₂H₆₀NaS₆Si₆: 947.1532; found: 947.1564. IR: 3160.2, 2955.5 (CH) cm^-1.

20

Compounds 2 and 3 were prepared from 10 and 11, respectively according to the method used for the preparation of 1 from 9. Compound 2: mp 252-253 °C (lit.¹³ 253-256 °C). ¹H NMR (400 MHz, CDCl₃): d = 7.40 (d, J = 5.4 Hz, 4 H), 6.96 (d, J = 5.4 Hz, 4 H). MS (EI): m/z = 328 (100) [M⁺]. HRMS (ESI): m/z [M + H]⁺ calcd for C₁₆H₉S₄: 328.9587; found: 328.9588. IR: 3101.2, 2926.0 (CH) cm^-1. Compound 3: mp 281-283 °C (sublimation). ¹H NMR (400 MHz, CDCl₃): d = 7.33 (d, J = 5.2 Hz, 2 H), 7.08 (d, J = 5.2 Hz, 2 H), 6.97 (d, J = 5.2 Hz, 2 H), 6.92 (d, J = 5.1 Hz, 2 H), 6.79 (d, J = 5.2 Hz, 2 H), 6.44 (d, J = 5.1 Hz, 2 H). ¹³C NMR (100 MHz, CDCl₃): d = 135.4, 133.4, 133.3, 132.1, 131.9, 131.5, 131.0, 130.4, 130.0, 129.7, 128.8, 126.1, 125.0, 124.9. MS (EI): m/z = 492 (48) [M⁺]. HRMS (ESI): m/z [M + H]⁺ calcd for C₂₄H₁₃S₆: 492.9341; found: 492.9341. IR: 3100.5, 2924.6 (CH) cm^-1.

21a

Crystal Data for 10: M = 701.36, C₃₄H₅₂S₄Si₄, triclinic, space group P1, a = 12.6217(9) Å, b = 13.2892(9) Å, c = 13.3125(9) Å, a = 110.0070(10)°, b = 111.4940(10)°, g = 96.1850(10)°, V = 1881.6(2) ų, Z = 2, D_calcd = 1.238 g/cm³. A colorless crystal of dimensions 0.30 × 0.23 × 0.11 mm was used for measurement at 293 (2) K with the w scan mode on a Bruker Smart APEX diffractometer with CCD detector using Mo-K_a radiation (l = 0.71073 Å). The data were corrected for Lorentz and polarization effects and absorption corrections were performed using SADABS^21b program. The crystal structures were solved using the SHELXTL^21c program and refined using full matrix least squares. The positions of hydrogen atoms were calculated theoretically and included in the final cycles of refinement in a riding model along with attached carbons. The final cycle of full-matrix least-squares refinement was based on 7240 independent reflections [I >2s(I)] and 357 variable parameters with R1 = 0.0667, wR2 = 0.1979. The supplementary crystallographic data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.uk/data_request/cif. Please quote the reference number CCDC: 652683.

21b Sheldrick GM. SADABS   University of Göttingen; Germany: 1996. 

21c Sheldrick GM. SHELXTL Version 5.1   Bruker Analytical X-ray Systems, Inc.; Madisonv / WI: 1997. 

22

Crystal Data for 11: M = 1045.17, C₄₃H₆₁Cl₃S₆Si₆, triclinic, space group P1, a = 11.8377(12) Å, b = 14.0164(15) Å, c = 17.9101(18) Å, a = 94.620(2)°, b = 103.881(2)°, g = 94.390(2)°, V = 2861.4(5) ų, Z = 2, D_calcd = 1.213 g/cm³. A colorless crystal of dimensions 0.30 × 0.11 × 0.11 mm was used for measurement at 293 (2) K. The structure was solved by the same methods as used for 10. The final cycle of full-matrix least-squares refinement was based on 11009 observed reflections [I >2s(I)] and 541 variable parameters with R1 = 0.0731, wR2 = 0.1255. The supplementary crystallographic data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.uk/data_request/cif. Please quote the reference number CCDC: 652684.

23a Rajca A. Wang H. Bolshov P. Rajca S. Tetrahedron  2001,  57:  3725 

23b Iyoda M. Kabir SMH. Vorasingha A. Kuwatani Y. Yoshida M. Tetrahedron Lett.  1998,  39:  5393 

23c Man YM. Mak TCW. Wong HNC. J. Org. Chem.  1990,  55:  3214