Direct access to thiomethyl/selenomethyl-substituted pyrazoles by combining isocyanide insertion into the inert C(sp)–S bond and intermolecular cyclization

Abstract

In this study, we present a facile and efficient one-pot synthetic protocol for the construction of thiomethyl/selenomethyl substituted pyrazoles. This protocol involves palladium-catalyzed isocyanide insertion into the C(sp)–S bond, followed by TMSN₃-involved CuI/Sc(OTf)₃ catalyzed intermolecular cyclization. The novel reaction of isocyanide insertion into the C(sp)–S bond achieves high atom economy while preserving the integrity of the CC bond. The subsequent cyclization process entails an intermolecular reaction between an alkynyl imine and TMSN₃, with the alkynyl imine playing a crucial role as an intermediate in the reaction pathway.