Conversion of 2-methylthio-4-trifluoroacetyl-5,6-dihydro-4H-1,3,4-thiadiazines intoα,β-unsaturated esters via carbanion-induced ring opening and desulfurization

Article abstract of DOI:10.1246/cl.1998.329

A convenient conversion of 2-methylthio-5,6-dihydro-4H-1,3,4-thiadiazines 1 into α,β-unsaturated esters was achieved through the procedure including trifluoroacetylation of 1, carbanion-induced ring opening of trifluoroacetamides 2, and reductive removal of heteroatom functionality of the resulting S-alkenyl hydrazinecarbodithioates 3. Treatment of 3 with a base under an aqueous condition also gave the corresponding 6-alkylidene-4H-1,3,4-thiadiazin-5-ones 6.