A general synthesis of benzofuran-2-thiolates via intramolecular addition of phenolates to alkynethiolates

Abstract

4-(ortho-Hydroxyaryl)-1,2,3-thiadiazoles can be transformed into benzofuran-2-thiolates via an intramolecular cyclization.

References

1. R. Raap and R. G. Micetich, Can. J. Chem., 1968, 46, 1057; G. L'abbé, W. Dehaen and B. Haelterman, J. Chem. Soc., Perkin Trans. 1, 1994, 2203.
2. R. Mayer, B. Hunger, R. Prousa and A. K. Müller, J. Prakt. Chem., 1967, 35, 294; A. Shafiee and I. Lalezari, J. Heterocycl. Chem., 1973, 10, 11.
3. C. D. Hurd and R. I. Mori, J. Am. Chem. Soc., 1955, 77, 5359; R. N. Butler and D. A. O'Donoghue, J. Chem. Soc., Perkin Trans. 1, 1982, 1223.
4. The synthesis of compound 6 has been reported before in a patent without experimental data: J. M. Muchowski and J. H. Fried, US Pat., 3 940 407, 1976; Chem. Abstr., 1976, 85, P63072a.
5. For instance, we used the isomeric 4-(4-hydroxyphenyl)-1,2,3-thiadiazole in a convergent synthesis of dendrimers: G. L'abbé, B. Haelterman and W. Dehaen, Bull. Soc. Chim. Belg., 1996, 105, 419.
6. The compounds 7a, 8b-e and 15 are new and were fully characterized by IR, mass, ¹H NMR and ¹³C NMR spectroscopy Benzofuran 8a has been prepared before: B. Capon and S. Q. Lew, Tetrahedron, 1992, 48, 7823.
7. P. C. Montevecchi and M. L. Navacchia, J. Org. Chem., 1995, 60, 6455; M. Wierzbich, G. Kirsch, D. Cagniant, M. Liebermann and T. W. Schafer, Chim. Ther., 1977, 12, 557.
8. F. Weselly and E. Zbiral, Liebigs Ann. Chem., 1957, 605, 98.