2-Amino-5-imino-4,5-dihydrothiazoles: synthesis by reaction of isocyanides with 2-amino-3-aza-1-thiabutadienes and base-induced rearrangement to imidazolines or diazolidines

Abstract

We report herein a new preparation of a series of dihydrothiazoles 4 from the [1+4] cycloaddition of isocyanides 1 with 2-amino-3-aza-1-thiabutadienes 3. We also describe the base-induced rearrangement of 4 (R 2 =H) into 2-aminoimidazoline-5-thiones 5 or 2-imino-4-thioxo-1,3-diazolidines 6, depending on the nature of the substituent R 1 . A mechanism is suggested for this new rearrangement