Copper Chloride-Catalyzed and Hydrochloric Acid-Mediated Chemoselective Protiodestannylations of Alkyl (Z)- or (E)-2,3-Bis(trimethylstannyl)-2-alkenoates. Stereoselective Preparation of Alkyl (E)- and (Z)-3-Trimethylstannyl-2-alkenoates

Treatment of alkyl (Z)-2,3-bis(trimethylstannyl)-2-alkenoates (7) with a catalytic amount of copper(I) chloride in N,N-dimethylformamide (DMF) containing a small quantity of water provides very good-to-excellent yields of alkyl (E)-3-trimethylstannyl-2-alkenoates (1). On the other hand, stirring of solutions of alkyl (Z)- (7) or (E)-2,3-bis(trimethylstannyl)-2-alkenoates (8) in DMF containing dilute hydrochloric acid produces, efficiently, alkyl (Z)-3-trimethylstannyl-2-alkenoates (2).