On the stability of the π-allyl intermediate in molybdenum-catalyzed asymmetric alkylations

Abstract Density functional theory calculations were performed on the apparent η 3 -π-allyl molybdenum intermediate that is observed during molybdenum-catalyzed asymmetric allylation [ Proc. Natl. Acad. Sci. U.S.A. 2004 , 101 , 5379]. The relative stabilities of geometric isomers, diastereoisomers, and π-allyl rotamers of the π-allyl molybdenum intermediate were investigated. Calculations show that the observed intermediate is the most stable because of two factors: (1) the observed π-allyl molybdenum intermediate maximizes the bonding and back-bonding interactions between molybdenum and the π-allyl ligand; and (2) the observed π-allyl molybdenum intermediate minimizes the steric interactions between the chiral ligand and the π-allyl group.