Regioselective and Stereospecific Rhodium-Catalyzed Allylic Cyanomethylation with an Acetonitrile Equivalent: Construction of Acyclic β‑Quaternary Stereogenic Nitriles

A highly regio­selective and stereo­specific rhodium-catalyzed cyano­methyl­ation of tertiary allylic carbonates for the construction of acyclic β-quaternary stereo­genic nitriles is described. This protocol represents the first example of a metal-catalyzed allylic substitution reaction using a triorgano­silyl-stabilized acetonitrile anion, which permits access to several carbonyl derivatives that are challenging to prepare using conventional pronucleophiles. The synthetic utility of the stereo­specific cyano­methyl­ation is further exemplified through the construction of an intermediate utilized in the total synthesis of both (−)-epilaurene and (−)-α-cuparenone.