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 ).