Reaction of substituted sulfenes with N,N‐disubstituted α‐amino‐methyleneketones. II. Synthesis of N,N‐disubstituted cis and trans 4‐amino‐3‐chloro‐3,4,5,6,7,8‐hexahydro‐1,2‐benzoxathiin 2,2‐dioxides, and 4‐amino‐5,6,7,8‐tetrahydro‐1,2‐benzoxathiin 2,2‐dioxides

Abstract

The polar 1,4‐cycloaddition of chlorosulfene (generated in situ from chloromethanesulfonyl chloride and triethylamine) to N,N‐disubstituted (E)‐2‐aminomethylenecyclohexanones I gave mixtures of N,N‐disubstituted cis and trans 4‐amino‐3‐chloro‐3,4,5,6,7,8‐hexahydro‐1,2‐benzoxathiin 2,2‐dioxides III and IV, except for N,N‐diphenyl enaminone which did not react. Only compounds IV could be separated from these mixtures by silica gel chromatography, with the exception of the piperidino adducts (III + IV)d, from which also IIId could be obtained pure. Compounds IV or mixtures III + IV were dehydrochlorinated with DBN in refluxing benzene to afford N,N‐disubstituted 4‐amino‐5,6,7,8‐tetrahydro‐1,2‐benzoxathiin 2,2‐dioxides V in satisfactory yields. Structural and conformational features of compounds III, IV and V were determined from uv, ir and nmr spectral data.

Synthesis and photochromism of some mono and bis (thienyl) substituted oxathiine 2,2-dioxides

“…29 The addition of sulfenes to enaminoketones to afford 4-amino-3,4-dihydro-1,2-oxathiine 2,2dioxides has been explored by Schenone et al 30 Interestingly, the formation of the unsaturated 1,2-oxathiine 2,2-dioxides was a relatively scarcely observed feature in these initial studies. 31 Indeed when chlorosulfene was added to an enaminoketone a subsequent facile base-promoted elimination of HCl was observed and the unsaturated 4-amino-1,2-oxathiine 2,2-dioxide resulted 32 and attempts to effect dehydrogenation of 4-amino-3,4-dihydro-1,2-oxathiine 2,2dioxides using excess DDQ met with variable results. 33 We elected to utilise the foregoing sulfene addition chemistry 30,34 and explore the subsequent elimination step required to obtain the unsaturated 1,2-oxathiine 2,2-dioxides.…”