Abstract
Enantiomerically enriched cyanohydrin O‐phosphates, prepared by enantioselective cyanophosphorylation of α,β‐unsaturated aldehydes, react regioselectively at the γ‐position with organocuprates derived from alkyl Grignard reagents and CuCN to afford chiral γ‐alkyl‐substituted α,β‐unsaturated nitriles. The configuration of the new C–C double bond is mainly (E) when the reaction is performed at –78 °C and (Z) when it is carried out at higher temperatures (0 °C). A high level of transfer of the chirality in the new stereocentre, corresponding to a stereospecific anti attack onto the cyanophosphate, is observed. Enantiomerically enriched (E)‐γ‐alkylated α,β‐unsaturated esters are prepared after subsequent methanolysis in a three‐step sequence from the corresponding α,β‐unsaturated aldehydes. In addition, the synthesis of (R)‐4‐methylnonan‐1‐ol, also known as the sex pheromone of the yellow mealworm Tenebrio molitor L, and its (S) enantiomer have been carried out in a four‐step route from (E)‐oct‐2‐enal. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)