Efficient 2-amino-2-thiazolin-4-ones or 2-iminothiazolidin-4-ones formation from thioureas and maleimides under solvent-free conditions
A facile method for the construction of 2-thiazolin-4-one or thiazolidin-4-one structure is described. Condensation reactions of thiourea (1a) and maleimides (2) under solvent-free conditions gave 2-amino-2-thiazolin-4-ones (3) via Michael-type reaction, while similar reactions of N-substituted thioureas (1b-d) with 2 afforded 2-iminothiazolidin-4-ones (4). Since the solvent-free reactions of 1 with 2a afforded 3 in good yields, the synthetic method was found to be effective from the viewpoint of green chemistry.