Regio- and stereo-selective synthesis of vinylstannanes. Transition-metal catalyzed stannylmetalation of acetylenes and conversion of enol triflates and vinyl iodides into vinylstannanes
Two new methods for the regio- and stereo-selective synthesis of vinylstannanes are described. (i) The reaction of terminal acetylenes with n-Bu3SnMgMe, n-Bu3SnAlEt2, or (n-Bu3Sn)2Zn in the presence of various transition-metal catalysts provides vinylstannanes in good yields. Whereas copper-catalyzed stannylmagnesation of 4-benzyloxy-1-butyne gives (E)-4-benzyloxy-1-tributylstannyl-1-butene exclusively