Dimroth-type N/S-interchange of N -aminothioglycolurils in the synthesis of 2-hydrazonoimidazo[4,5- d ]thiazolones.

An original method for the synthesis of 2-hydrazonoimidazo[4,5- d ]thiazolone derivatives has been developed based on a one-pot acid-induced sequence of hydrazone formation from 3-thioxoperhydroimidazo[4,5- e ]-1,2,4-triazinones and aromatic aldehydes, triazine ring contraction to imidazolidine one, and Dimroth-type N/S-interchange of N -aminothioglycolurils formed in situ into 2-hydrazonoimidazo[4,5- d ]thiazolones. 3-Phenylacroleine derivatives are also suitable substrates for the reaction with thioxoperhydroimidazotriazinones.