A study of the reactions of 1,3‐diynes with organo‐cuprates and ‐argentates

Abstract
1,3‐Diynes HCCCCR′ (1, R′  H or Ph) are converted by cuprates [RCuY]M′ (R  alkyl; Y  Cl, Br or R; M′  Li, MgCl or MgBr) into a mixture of [HC(CuY)C(R)CCR′]M′ (2) and [RCHC(CuY)CCR′]M′ (3). When R is n‐alkyl, adducts2are the major products; adducts3are preferentially formed when R is a branched alkyl. Organoargentates [RAgY]MgCl (R  alkyl, Y  Br or R) convert diynes1selectively into [RCHC(AgY)CCR′]MgCl (6). The latter regiospecific reaction has been used to prepare functionally substituted enynes RCHC(E)CCR′ (7: E  Br, I, allyl, CO2H) in good yields.