Titanium-mediated Carbometallation of Homoallylic Alcohols
Addition of zinc dichloride as an additive allows for the titanium-mediated carbometalation of homoallylic alcohols with Grignard reagents. The zinc dichloride additive successfully inhibits the B-hydride elimination of the titanium intermediate. The unsaturated products are obtained in up to 90 percent yield and up to >20 to 1 ratio of the carbometallation to oxidative arylation products. Subsequent electrophilic trapping is possible with elemental halides to yield the respective halohydrin products or oxidation to yield the diol products. The reaction is tolerant of both alkyl and aryl substituents on the homoallylic alcohol. This reaction allows ready access to unsaturated secondary alcohols or further functionalized products from an initial homoallylic alcohol.