Dilithium dimethylcyanocuprate

More recently, Hoppe et all63 also reported a stereoselective synthesis of a P -amino-u -hydroxy enone and its transformation to a 1,2-dihydroxyethylene isostere (Scheme 29). The addition of dilithium dimethylcyanocuprate to the conjugated C=C bond proceeds smoothly to produce a Z-enolate. The C-methoxycarbonylation with methyl cyanoformate forms the epimeric mixture of the 3-oxo ester. The product is then reduced with sodium cyanobo-rohyde to provide a protected form of the 1,2-dihydroxyethylene isostere. 

---