Aryl carbonyls and carbinols as proelectrophiles for Friedel-Crafts benzylation and alkylation.

Friedel-Crafts benzylation/alkylation using benzylic, tertiary, and homobenzylic alcohols; aryl aldehydes, aryl ketones, and the highly challenging aryl carboxylic acids and esters as proelectrophiles has been achieved using borane-ammonia and TiCl 4 , greatly broadening the scope of useable substrates. Incorporation of deactivated aromatic proelectrophiles and specificity for substitution at the benzylic position are demonstrated in the synthesis of various di- and triarylalkane products. Dual protocols allow for the use of standard nucleophilic solvents (benzene, toluene, etc. ) or for stoichiometric addition of more valuable nucleophiles including furans, thiophenes, and benzodioxoles.