Studies in sulfur heterocycles. Part 16. Use of 7-hydroxy-1-benzothiophene in the synthesis of substituted benzothiophene derivatives and tricyclic compounds incorporating a fused thiophene ring

Abstract

Heteroatom directed ortho-metallation on N,N-diethyl-7-carbamoyloxy-1-benzothiophene, readily available from 7-hydroxy-1-benzothiophene enabled regioselective substitution in the 6-position. Both 7- and 4-hydroxy-1-benzothiophene were used in the annelation of 5- or 6-membered oxygen heterocycles onto the 1-benzothiophene molecule through sequential Claisen rearrangement–ring closure reactions. The nature of the annelated ring depends upon the reaction conditions.

References

1. Part 15. S. S. Mandal, J. Chakraborty and A. De, J. Chem. Soc., Perkin Trans. 1, 1999, 2639.
2. Abstracted in part from the PhD thesis of S. C. G. submitted to Jadavpur University ( 1999).
3. (a) A. Mustafa, “Furopyrans and Furopyrones”, The Chemistry of Heterocyclic Compounds, ed. A. Weissberger, Wiley Interscience, New York and London, 1967; (b) A. Mustafa, S. M. A. D. Zayed and A. Emran, Ann., 1967, 704.
4. A. De, J. S. A. Brunskill and H. Jeffrey, Indian J. Chem., Sect. B, 1984, 23, 918.
5. (a) P. M. Chakraborti, N. B. Champman and K. Clarke, J. Chem. Soc. C, 1969, 1; (b) C. M. Asprou, J. S. A. Brunskill, H. Jeffrey and A. De, J. Heterocycl. Chem., 1980, 17, 87.
6. S. Mukherjee and A. De, J. Chem. Res., 1994, (S) 295, (M) 1735.
7. (a) cf.B. Iddon and R. M. Scrowston, in Advances in Heteocyclic Chemistry, eds. A. R. Katritzky and A. J. Boulton, vol. 11, Academic Press, New York and London, 1970; andR. M. Scrowston, in Advances in Heterocyclic Chemistry, eds. A. R. Katritzky and A. J. Boulton, vol. 29, Academic Press, New York and London, 1980 for earlier synthesis of 7-hydroxy-1-benzothiophene; (b) a high yielding but lengthy synthesis was reported by L. K. A. Rahman and R. M. Scrowston, J. Chem. Soc., Perkin Trans. 1, 1983, 2973.
8. S. S. Samanta, S. C. Shosh and A. De, J. Chem. Soc., Perkin Trans. 1, 1997, 2683.
9. S. S. Samanta, S. C. Ghosh and A. De, J. Chem. Soc., Perkin Trans. 1, 1997, 3873.
10. V. Snieckus, Chem. Rev., 1990, 90, 879.
11. S. S. Mandal, S. S. Samanta, C. Deb and A. De, J. Chem. Soc., Perkin Trans. 1, 1998, 2559.
12. M. P. Sibi, J. W. Dankward and V. Snieckus, J. Org. Chem., 1986, 51, 273.
13. H. Ishii, T. Ishikawa, S. Takeda, S. Ueki, M. Suzuki and I. Haryana, Chem. Pharm. Bull., 1990, 38, 1775.