Effective and catalyst-free preparation of thiazolidines via novel [3 + 2] annulation of 1,4-dithiane-2,5-diol and benzothiazolimines

A novel and moderate diastereoselective [3 + 2] annulation of 1,4-dithiane-2,5-diol and benzothiazolimines has been developed for the efficient and one-step preparation of highly steric thiazolidines in excellent yields (up to 99%) and moderate diastereoselectivities (1:1 - 2.4 : 1) under mild conditions within a few minutes. A series of thiazolidines compounds were obtained and scale-up experiment was conducted with excellent results and their absorption, metabolism, and toxic properties were evaluated according to ADMET's estimation with good results demonstrating the potential applications of this protocol.