An ab initio molecular orbital study of the reduction of carbonyls by alkylaluminum complexes

Semi-empirical and ab initio MO methods were used to explore mechanisms for the reduction of carbonyls by alkylaluminum reagents. Two distinct pathways have been observed experimentally, depending on the stoichiometric amounts of the reagents present. The corresponding intermediates and transition structures have been characterized. Alkylaluminum alkoxides are generally less reactive than the analogous alkylaluminum complexes. We suggest that the controlling factor here is not binding of the substrate, but the higher barrier to reaction of the alkoxide.