In(OTf)3-catalyzed thiolysis of 1,2-epoxides by arylthiols under SFC. A new approach for the synthesis of thiazolopyridinium ionic liquids

Abstract

The efficiency of In(III)-catalyzed thiolysis of safrole oxide (1) by phenylthiol (2a) under SFC or in an organic medium, strongly depends on its associated counterion. In(OTf)₃ has proven to be a very efficient catalyst and the use of solvent-free condition (SFC) results in the highest catalytic efficiency. In the presence of 2 mol% of this salt the reactions of 1,2-epoxides 1, 5, and 8 by thiols 2a–f, have allowed the corresponding β-hydroxy sulfides to be obtained at 30 °C in generally short times, high yields and with C-β-regioselectivity. In addition two representatives of a new class of [1,3]thiazolo[3,2-a]pyridin-4-ium-based ionic liquids, 11 and 12, have been prepared by a simple one-pot procedure by using as a key step the thiolysis of 1,2-epoxyhexane (5) by 2-mercaptopyridine 2f.