Three-Component Coupling Reactions of Thioformamides with Organolithium and Grignard Reagents

Significance

The use of N,N-dialkylthioform­amides for the generation of tertiary amines via a novel three-component coupling reaction with ­organolithium and Grignard reagents is demonstrated. Thus, a variety of valuable tertiary amines, including the biologically significant diarylmethyl­piperazines, were synthesized. It is noteworthy that the order of addition of the organolithium and Grignard reagents is vital to the success of the reaction. Remarkably, an excess of the organolithium reagent, which is first added to the N,N-dialkyl­thioformamide, does not interfere with the outcome of the reaction. In addition to the formation of tertiary amines a new thiolating agent, supposedly LiSMgBr, is formed during the coupling reaction.