Addition reactions with 1,3-Thiazole-5(4H)-thiones; Synthesis of spirocyclic and fused bicyclic sulfur heterocycles

Various 1,6-dithiaspiro heterocycles can be synthesized from 1,3-thiazole-5(4H)-thiones via 1,3-dipolar cycloadditions, Diels-Alder reactions, ring expansion of oxiranes, and C-alkenylation followed by radical cyclization. 1,3-Thiazole-5(4H)-thiones with a vinyl substituent at C(4) are photochemically transformed into fused polycyclic compounds or, after C-alkylation to the corresponding 4,5-dihydro-5-mercapto-1,3-thiazoles, into fused bicyclic compounds via radical cyclization. With mCPBA, 1,3-thiazole-5(4H)-thiones are oxidized to thionoxides, which fail to undergo cycloaddition reactions