Syntheses of 4H-thiopyran-4-one 1,1-dioxides as precursors to sulfone-containing analogues of tetracyanoquinodimethane

Article abstract of DOI:10.1021/jo00111a027

Synthetic routes to the unsubstituted 4H-thiopynan-4-one 1,1-dioxide (5a), 2,6-dialkyl-substituted, 2-aryl- or 2-heteroaryl-6-alkyl-substituted, 2,6-diaryl- or diheteroaryl-substituted, and 2-heteroaryl-6-aryl-substituted 4H-thiopyran-4-one 1,1-dioxides 5b-s are described. Sodium hydrosulfide hydrate in buffered aqueous alcohol can be used as a substitute for hydrogen sulfide gas for the introduction of sulfur to methyl acrylate, to 1,5-disubstituted-1,4-pentadien-3-ones 13, or to 1,5-disubstituted-1,4-pentadiyn-3-ones 17. The double dehydrogenation of 2,3,5,6-tetrahydrothiopyran-4-one 1,1-dioxides 13 with iodine-DMSO-sulfuric acid gives thiopyran-4-one 1,1-dioxides 5 in good yield and small amounts of 1,4-pentadien-3-ones 13. 2,3,5,6-Tetrahydrothiopyran-4-one 1,1-dioxide (9) and 5,6-dihydrothiopyran-4-one 1,1-dioxide (12), which lack aryl or heteroaryl substituents, give poor yields of 4H-thiopyran-4-one 1,1-dioxide (5a) with iodine-DMSO-sulfuric acid.