Hydrometallation of 1-octene with grignard reagents. Alkylmagnesiums and alkylmagnesium hydrides catalyzed by dicyclopentadienyltitanium dichloride

Abstract

The hydrometallation of l-octene by a series of Grignard reagents (EtMgCl, EtMgBr, n-PrMgCl, i-PrMgCl, n-BuMgCl, sec-BuMgCl, iso-BuMgCl, iso-BuMgBr and iso-BuMgI), dialkylmagnesium compounds (Me 2Mg, Et 2Mg, n-Pr 2Mg, iso-Pr 2Mg, n-Bu 2Mg, sec-Bu 2Mg, iso-Bu 2Mg and t-Bu 2Mg), alkylmagnesium hydrides (RMgH, where R = Me, Et, T-Bu, Cp and Ph) and magnesium hydrides (MgH 2, HMgCl and HMgBr) in the presence of 5 mol% dicyclopentadienyltitanium dichloride (Cp 2TiCl 2) in THF has been investigated. The percent yield of octane (produced on hydrolysis of the product) vs. time was plotted for several reactions in order to compare the effect of individual reagents. Most alkylmagnesium compounds with β hydrogen atoms gave primarily the hydrometallation product, although t-Bu 2Mg produced isomerized starting material. MeMgH gives the best yield of octane on hydrolysis of the reaction mixture. A mechanism is proposed which accounts for all observations.