An effective synthesis of fused cyclic thiopyrans and pyrans by molybdenum(VI) sulfide catalyzed reduction of the corresponding thiopyranones and pyranones

Article abstract of DOI:10.1002/jhet.5570320252

The synthesis of fused cyclic dihydrothiopyrans 2a-c from dihydrothiopyranones 1a-c and thiopyrans 2d-f from thiopyranones 1d-f by catalytic reduction over molybdenum(VI) sulfide (MoS₃) has been studied. The hydrogenolysis of the carbonyl group of 1a-f over MoS₃ catalyst proceeded selectively to give the corresponding 2a-f in high yields. Neither alcohols nor olefins were not detected in the products. The method was also applied successfully to the synthesis of dihydropyran 2h and pyran 2g from dihydropyranone 1h and pyranone 1g.