New preparation of benzylic aluminum and zinc organometallics by direct insertion of aluminum powder.

The reaction of commercial Al-powder (3 equiv) and InCl(3) (1-5 mol %) with benzylic chlorides provides various functionalized benzylic aluminum sesquichlorides under mild conditions (THF, 20 °C, 3-24 h) without homocoupling (<5%). These new benzylic organometallics reacted smoothly with various electrophiles (Pd-catalyzed cross-couplings, or Cu-mediated acylations, allylations, or 1,4-addition reactions). Electron-poor benzylic chlorides or substrates prone to Wurtz coupling can be converted to benzylic zinc compounds by the reaction of Al-powder in the presence of ZnCl(2).