Thorpe–Ingold effect in the reaction of vicinal amino primary alcohol hydrogen sulfates and carbon disulfide

The Thorpe–Ingold effect is a key factor that affects the ring-closure rates and efficiency, as well as the structure of products in some ring-closure reactions. The reaction of vicinal amino primary alcohol hydrogen sulfates and carbon disulfide in the presence of potassium hydroxide produces the desired 4,4-disubstituted thiazolidine-2-thiones, and their isomers 5,5-disubstituted derivatives companying with their oxygen analogues 4,4-disubstituted oxazolidine-2-thiones. The formation of 5,5-disubstituted thiazolidine-2-thiones was rationalized via 2,2-disubstituted aziridine-1-carbodithioate intermediates, which were generated due to the Thorpe–Ingold effect. 4,4-Disubstituted oxazolidine-2-thiones were generated from carbon disulfide and free amino alcohols yielded via basic hydrolysis of active amino alcohol hydrogen sulfates in the reaction system.