RESUMEN
A series of 6-styryl-1,2-oxathiine 2,2-dioxides have been efficiently obtained by a two-step protocol from readily available (1E,4E)-1-(dimethylamino)-5-arylpenta-1,4-dien-3-ones involving a regioselective sulfene addition and subsequent Cope elimination. Pd-Mediated direct C-H bond functionalisation of the 6-styryl-1,2-oxathiine 2,2-dioxides and a wider selection of 5,6-diaryl substituted 1,2-oxathiine 2,2-dioxides proceeded smoothly to afford C-3 (hetero)aryl substituted analogues and the results are contrasted with those of a complementary bromination - Suzuki cross-coupling sequence. Whilst the cycloaddition of benzyne, derived from in situ fluoride initiated decomposition of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate, to the substituted 1,2-oxathiine 2,2-dioxides resulted in low yields of substituted naphthalenes, the addition of 4-phenyl-1,2,4-triazoline-3,5-dione to the 6-styryl-1,2-oxathiine 2,2-dioxides afforded novel 5,9-dihydro-1H-[1,2]oxathiino[5,6-c][1,2,4]triazolo[1,2-a]pyridazine-1,3(2H)-dione 8,8-dioxides through a silica-mediated isomerisation of the initial [4 + 2] adducts.
RESUMEN
1,2-Oxathiine 2,2-dioxides have been obtained from their respective 3,4-dihydro-4-dimethylamino precursors, for the first time, by a mild Cope elimination of the 4-dimethylamino function. The application of the 1,2-oxathiine 2,2-dioxide scaffold in materials chemistry is exemplified by the efficient P-type photochromism of the 5,6-bis(2,5-dimethyl-3-thienyl) substituted oxathiine 2,2-dioxides.
RESUMEN
Diversely substituted 1,2-oxathiine 2,2-dioxides, including 3,5,6-triaryl-, 3,6-diaryl-, 3,5-diaryl-, 5,6-diaryl- and selected fused heterocyclic analogues, have been efficiently obtained by the application of a mild Cope elimination of a 4-amino moiety from the requisite 4-amino-3,4-dihydro-1,2-oxathiine 2,2-dioxides, which themselves were readily obtained by the addition of sulfenes to enaminoketones.