Asymmetric Substitution Reactions Catalyzed by a Chiral Phosphoric Acid

Abstract

Nucleophilic substitution reactions on the sp2- or sp3-hybridized carbon, including formal substitution such as addition-elimination sequence, are one of the fundamental transformations in organic synthesis. Compared with the addition reactions, development of catalytic enantioselective substitution reactions is still rare. This account summarizes our recent efforts to solve the problems by using chiral phosphoric acid catalysts. The first topic is the catalytic kinetic resolution of racemic secondary alcohols by an addition-elimination type acylation reaction. The desymmetrization of σ-symmetrical acid anhydrides is also described. The second topic is the enantioselective intramolecular SN2' reaction. We made clear that the choice of the leaving group is quite important. The last topic is the catalytic kinetic resolution of racemic β-aminoalcohols by nucleophilic benzylation reaction. Chiral phosphoric acid works as a nucleophilic catalyst to form the corresponding phosphonate in situ as a chiral electrophilic intermediate.