studied with respect to the degree of substitution at the carbanion site. Attack by tertiarycarbanions is not observed, the products reverting completely to starting materials under the reaction conditions. When dibasic carbon acids were employed, discrimination against the products of attack by a tertiary centre was observed. The expected products from tertiary attack have been independently synthesized
Ring transformation of 2-substituted isothiazol-3(2H)-ones to 3,4-dihydro-1,3-thiazin-4(2H)-ones by a novel carbene addition–ring expansion sequence
作者:Wilfrid D. Crow、Ian Gosney、Raymond A. Ormiston
DOI:10.1039/c39830000643
日期:——
Rhodium(II)-catalysed addition of diazo compounds to 2-substituted isothiazol-3(2H)-ones (1) results in a ready conversion into hitherto unknown 3,4-dihydro-1,3-thiazin-4(2H)-ones (2) in high yield.
3-Alkylamino- and 3-arylamino isothiazole dioxides unsubstituted at C-4 and C-5 were synthesized starting from dithiopropionic amides. Taking advantage of the direct chlorination during the cyclization process or realizing an addition–elimination process with bromine on the final 3-aminoisothiazole dioxide derivatives, the corresponding 5-chloro-, 4,5-dichloro- or the 4-bromoisothiazole dioxides could