Synthesis of 4,4-Disuhstituted 1,3-Thiazol-5(4H)-thionesAn easy synthesis for the 1,3-thiazol-5(4H)-thiones 5, a class of heterocycles which have hitherto only been available with difficulty, is described. Reaction of 3-amino-2H-azirines 25 with thiocarboxylic acids at 0" yields rnonothiodiamides oftype 20 (Scheme 6 ) which, on treatment with Lowsson reagent at loo", undergo thiation and cyclization to give 5 in good yield.