Carbanions cycloalkenyl

An allylic sulfenate, like 199, is known to be in equilibrium with allylic sulfoxide, like 196, although its concentration is usually low . Various allylic sulfoxides can be prepared by treatment of allylic alcohols with arenesulfenyl chlorides . Evans and coworkers prepared various allylic alcohols by treating the corresponding allylic sulfoxides with trimethyl phosphite. For example, the carbanion from a cycloalkenyl sulfoxide 201 was readily alkylated at the a-position by treatment with alkyl halide. The resulting alkylated derivative 202 was then treated with trimethyl phosphite and 3-substituted cycloalkenol was obtained. Alkylation of acyclic allylic sulfoxide 204 gave... 

Bicyclic lactones8,60 are readily prepared from the corresponding cycloalkenyl acetic acids via iodolactonization and subsequent hydrogen iodide elimination. They are interesting starting materials for the stereoselective synthesis of civ-substituted cycloalkenes 25 and 26. The regiose-lectivity is determined by charge repulsion between the soft carbanion and the carboxylate anion. 

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