Treatment of terminal alkynes 1 with the organocopper reagents derived from Grignard reagents, cuprous iodide, and lithium bromide (molar ratio 2: 1: 2) at low temperature followed by the addition of chlorotrimethylsilane gave the 2, 2-disubstituted vinylsilanes 2 with complete regio-and stereospecificity (syn addition). Electrophilic substitution of 2 with ICl, Brz, and acetyl chloride gave the corresponding vinyl iodides, bromides, and a,@- ...
