Base-Catalyzed Halogen Dance Reaction at Thiophenes: A Spectroscopic Reinvestigation of the Synthesis of 2,5-Dibromo-3-(trimethylsilyl)thiophene

Journal of Organic Chemistry

Volumn 55, Issue 10, 1990, Pages 2993-2995

  Fröhlich, Hannes ^a   Kalt, Wolfram ^a  

^a VIENNA UNIVERSITY OF TECHNOLOGY   (Austria)

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Indexed keywords

EID: 0000086864     PISSN: 00223263     EISSN: 15206904     Source Type: Journal    
DOI: 10.1021/jo00297a003     Document Type: Article

References (21)

1. Moses, P.; Gronowitz, S. Ark. Kem. 1961, 18, 119.
2. Gro-nowitz, S. Adv. Heterocycl. Chem. 1963, 1, 75.
3. Reinecke, M. G.; Adickes, H. W.; Pyun, C. J. Org. Chem. 1971, 36(18), 2690.
4. Reinecke, M. G.; Hollingworth, T. A. J. Org. Chem. 1972, 37(26), 4257.
5. Kano, S.; Yuasa, Y.; Yokomatsu, T.; Shibuya, S. Heterocycles 1983, 20(10), 2035.
6. Grosvenor, P. R.; Fuller, L. S. Eur. Pat. Appl. 88201494.7, 12.07.88
7. Reinecke, M. G.; Adickes, H. W. J. Am. Chem. Soc. 1968, 90, 511.
8. Bunnett, J. F. Acc. Chem. Res. 1972, 5, 139.
9. Taylor, E. C.; Vogel, D. E. J. Org. Chem. 1985, 50(7), 1002.
10. Sauter, F.; Fröhlich, H.; Kalt, W. Synthesis 1989, 771.
11. Davies, G. M.; Davies, P. S. Tetrahedron Lett. 1972, 3507
12. Pham, C. v.; Macomber, R. S.; Mark, H. B., Jr.; Zimmer, H. J. Org. Chem. 1984, 49(26), 5250.
13. In continuation of this work some papers on polythiophenes trusting on these postulated structures 7a-d as monomeric starting compounds have been published: Czerwinsky, A.; Zimmer, H.; Amer, A.; Pham, C. v.; Pons, S.; Mark, H. B., Jr. J. Chem. Soc., Chem. Commun. 1985, 1158.
14. Pham, C. v.; Czerwinsky, A.; Zimmer, H.; Mark, H. B., Jr. J. Polym, Sci., Polym. Lett. 1986, 24,103.
15. Czerwinsky, A.; Cunningham, D. D.; Amer, A.; Schrader, J. R.; Pham, C. v.; Zimmer, H.; Mark, H. B. Jr. J. Electrochem. Soc. 1987. 134(5). 1158.
16. All NMR spectra were recorded in CDCl3.
17. The incremented chemical shifts for silylated bromothiophenes were calculated by adding the increments we have evaluated for the trimethylsilyl substituent (see Table II) to the shifts of appropriate bromothiophenes in CDC13. 2,3-Dibromothiophene (1): 111.1 (C2), 113.9 (C3), 126.8 (C5), 129.9 (C4). 2,5-Dibromothiophene (2): 111.5 (C2, C5), 130.2 (C3, C4) (see also ref 8). 2,4-Dibromothiophene (4): 109.4 (C4), 112.9 (C2), 124.2 (C5), 131.8 (C3). 2-Bromothiophene: 111.9 (C2), 126.7 (C5), 127.4 (C4), 129.6 (C3). 3-Bromothiophene: 109.8 (C3), 122.4 (C2), 126.3 (C5), 129.6 (C4). The carbon assignments are according to Reinecke, M. G., Pedaja, P. In The chemistry of heterocyclic compounds; Weissberger, A., Taylor, E. C., Eds.; John Wiley and Sons, Inc.: New York, 1986, Vol. 442, Chapter III, pp 463–466. The shift data reported herein are, as they have been recorded neat or in acetone-d6, slightly different from our values obtained in CDCl3.
18. Thiophene 13C NMR (CDCl3): 6 124.9 (C2, C5, 126.7 (C3, C4).
19. Effenberger, F.; Habich, D. Justus Liebigs Ann. Chem. 1979, 842.
20. To a stirred solution of 12.9 mmol of diisopropylamide in dry tetrahydrofuran (THF) at -80 °C was added 1 g (6,4 mmol) of 10 in 10 mL of dry THF rapidly. After being stirred for 30 min at -80 °C, a solution of 1.35 g (12.8 mmol) of cyano bromide in 10 mL of dry THF was added dropwise. Stirring was continued for 15 min, and then the solution was hydrolyzed. The organic phase was separated and dried (anhydrous Na2S04), and the THF was evaporated. The resulting brown residue was distilled in vacuum. Fraction I: bp 150 °C (80 mm); yield 0.8 g (53%); no further purification; 1H NMR (CDCl3) δ 7.30 (d, 1 H, JAB = 1.2 Hz), 7.08 (d, 1 H, jab=1.2 Hz), 0.26 (s, 9 H); 13C NMR (CDC13) -0.9 (q), 112.5 (s, C2), 132.7 (d, C5), 133,8 (d, C3), 142.9 (s, C4). Fraction II: distilled twice; bp 150 °C (20 mm); yield 0.5 g (25%) of 7a; spectroscopic data see Table IV. Anal. Calcd for C7H10Br2SSi: C, 26.77; H, 3.21. Found: C, 27.02; H, 3.21.
21. 2,3-Bromothiophene (1) was reacted with 1 equiv of BuLi in dry Et20 at -80 °C (similar to: Seconi, G.; Eaborn, C.; Stamper, J. G. J. Organomet. Chem. 1981, 204, 153) to form via metal-halogen exchange (3-bromo-2-thienyl)lithium. Subsequent quenching with TMSC1 afforded product 11 in high yield (87% upon distillation) and without any side products. 1H NMR (CDC13): 5 7.44 (d, 1 H, JAB = 4.9 Hz), 7.09 (d, JAB = 4.9 Hz), 0.40 (s, 9 H).