Addition of unsaturated propargyl, allyl and benzyl Grignard Reagents to acetylenic or

allylic alcohols.

John H. MacMillan and Alfred Viola

Department of Chemistry, Northeastern University, Boston, Massachusetts, 02115.

Abstract:

-Unsaturated alkenyl or propargyl alcohols add propargyl, allyl and benzyl Grignard Reagent at the -position of the alcohol, yielding methylene or methyl substituted alcohols in moderate yield. Alkenes and alkynes with no alcohol or alcohols with no -unsaturated functionality failed to react. Saturated Grignards gave very low yields. The mechanism is postulated to involve a cyclic transition state with an initial complex of the hydroxyl of the alcohol to the magnesium of the Grignard. The reaction has synthetic utility for the production of 2-methylene substituted alcohols.