Mechanochemical synthesis of thiolactams and other thioamides using Lawesson’s reagent

Abstract

A mechanochemical method has been developed for the synthesis of primary, secondary, and tertiary thioamides from their corresponding amides using Lawesson’s reagent for the first time. The mechanochemical thionation reactions reported herein produced thiolactams 2-pyrrolidinethione, 1, 2-piperidinethione, 2, 1-aza-2-cycloheptanthione, 3, 1-aza-2-cyclooctanthione, 4, and N-methylpyrrolidine-2-thione, 5, as well as acyclic thioamide-containing species, thioacetamide, 6, thiobenzamide, 7, and thionicotinamide, 8. In the course of these syntheses, the solid-state structure of 2-pyrrolidinethione, 1, was determined by single crystal X-ray diffraction and compared to 2-pyrrolidinone.