[摘要]:hydrolysis of vicinal 2,3-diisothiocyanato carboxylates. The unsym. 2-thioxoimidazolidine-4,5-dicarboxylates were prepd. by addn. of a stoichiometric amt. of primary and secondary amines to vicinal 2,3-diisothiocyanato carboxylates. The resulting imidazolidines were found to be convenient reactants for the construction of a new bicyclic imidazo[2,1-b]thiazole system. The addn. of a 2-fold excess of amine to vicinal 2,3-diisothiocyanato carboxylates gave rise to competitive condensations yielding bi-imidazolidine and bi-1,2,4-triazine derivs.