Mechanochemical sulfenylation of maleimides

Abstract

Herein, we present a mechanochemical approach for the sulfenylation of maleimides to afford sulfenylsuccinimides under solvent-, catalyst-, heating-, and base-free conditions. The reaction proceeds via a thia-Michael addition mechanism and, in several cases, allows product isolation through simple extraction using ethyl acetate. The method also employs LiCl as a grinding auxiliary (with NaCl as a viable alternative in some cases), thereby replacing traditional solvents with less polluting and easily disposable solid materials. The scope of the reaction was evaluated using 30 different substrates, including variations in the nucleophiles, the maleimides, and additional Michael acceptors. Furthermore, we demonstrate selected applications of the resulting sulfenylsuccinimides.