Abstract
On irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b, synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a, b, undergo an intramolecular (2+2)-cycloaddition reaction of the C=S and C=C bonds to give the tricyclic thietane derivatives 3a, b.