Rhodium-Catalyzed Allylic Substitution with an Acyl Anion Equivalent: Stereospecific Construction of Acyclic Quaternary Carbon Stereogenic Centers

A highly, regio- and stereospecific rhodium-catalyzed allylic alkylation of tertiary allylic alcohol derivatives with a cyanohydrin pronucleophile is described. This direct and operationally simple protocol provides a fundamentally novel approach toward the synthesis of alpha-quaternary substituted ketones and circumvents many of the inherent problems associated with conventional enolate alkylation reactions. The Stereospecific variant of this reaction provides the enantiomerically enriched alpha-quaternary substituted allylic aryl ketone, which is a particularly challenging intermediate for more conventional enolate-bsed strategies.