Stereocontrol in Horner-Wadsworth-Emmons Condensations of a gem-Dimethylcyclopropyl Aldehyde with α-Substituted Phosphono Acetates

Article abstract of DOI:10.1021/jo00288a026

Oxidative cleavage of 2-carene provides a keto aldehyde attractive as a synthon for terpenoids containing gem-dimethylcyclopropyl rings.However, the sensitivity of this keto aldehyde to intramolekular aldol condensations proscribes the use of many standard conditions for Wadsworth-Horner-Emmons condensations that might be used to extend this carbon skeleton.Through use of dioxolane-containing phosphono acetates and lithium bases, it is possible to obtain olefin derivatives of this keto aldehyde with reasonable selectivity for either E or Z stereochemistry depending on the choice of phosphonate esters.