Reaction of α-halo ketone with 2-aminothiol: a new synthesis of thiazolidines with the oxo group migrated to the original position occupied by halogen atom

The reaction of 2-bromo-3-oxo steroids with 2-aminoethanethiol led to the stereoselective formation of spiro[steroid-3,2′-thiazolidin]-2-ones as the major product. With both cyclic and acyclic α-halo alkanones, the reaction gave the thiazolidines with the oxo group migrated to the original position occupied by the halogen atom. In addition, it was found that the use of microwaves affords improvement of yields and shortening the reaction time in comparison with usual conditions.