Lithium isohexylcyanocuprate

The reaction has been extended to 1,4-chirality transfer. For instance, epoxide (54) reacts with lithium isohexylcyanocuprate to afford isomerically pure (55 Scheme 20). This strategy has been applied to the total synthesis of prostaglandins. ... 

The 1,4-addition of alkyl cyanocuprates to epoxides to form cyclic a,/ -unsaturated ketones provides a stereoselective method for conversion of dehydro-epiandrosteronc into cholesterol (4) and other related steroids. Thus the keto epoxide 2 (obtained from dehydroepiandrosterone in 55% overall yield in three steps) reacts with lithium isohexylcyanocuprate to give the adduct 3, which can be converted to cholesterol (4) in several known steps.27... 

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