A General Method for the Preparation of γ-Substituted Cyclohexenals and Cycloheptenals

Article abstract of DOI:10.1021/jo00221a015

A general procedure for the preparation of γ-substituted or β'-unsaturated cycloalkenals is described.Starting from 2-cycloalkenones substituents may be introduced as nucleophiles by 1,4-addition followed by trapping of the regiospecifically generated enolate (86-92percent).Peracid oxidation of the enol silane derivative produces an α-hydroxy ketone which, after protection (70-93percent), is homologated to an enol ether by a Horner-Wittig reaction.Mild hydrolysis of the labile vinylogous acetal produces the aldehydes in good yields (62-75percent).Advantages of this method in comparison to known procedures are discussed as are other unsuccessful approaches to this substitution pattern.