Specifically, reaction of the commercially available bromo alcohol 4 with H2C¼CHMgBr in the presence of catalytic amounts of CuI affords the rather volatile alkene (X ¼ OH),[11] which is immediately converted without further purification into tosylate 5 to minimize losses during workup (65% over both steps). Subsequent treatment with LiBr in acetone affords the corresponding bromide 6. The enantiomerically pure Grignard reagent derived therefrom ...
