Synthesis of Some Stable 7-Halo-1,4-thiazepines. Potential Substituted Penam Precursors

Abstract

The synthesis of some new 3-carbomethoxy-5-oxoperhydro-1,4-thiazepines is described. Halogenation studies led to the preparation of three potential substituted penam ring precursors: 6,7-dibromo-3-carbomethoxy-5-oxoperhydro-1,4-thiazepine, 3-carbomethoxy-6,7-dichloro-5-oxoperhydro-1,4-thiazepine, and 3-carbomethoxy-7-chloro-6,6-dimethyl-5-oxoperhydro-1,4-thiazepine. Preliminary studies on the reactivity of these α-halothioethers showed that methanolysis to the corresponding methoxy-thiazepines may be carried out in nearly quantitative yields in the case of the first two derivatives; the third compound, on the other hand, led to an open-chain dehydrohalogenated product where C-7 is converted to the corresponding dimethyl acetal.