Asymmetric autocatalysis: Novel structures, novel mechanism?

The amplifying asymmetric autocatalysis discovered by Soai and coworkers in 1995 does not fit easily into the extensively investigated framework of organozinc alkylation of aldehydes. In that case the catalyst is a monomeric Zn chelate that functions as both Lewis acid and Lewis base, permitting the simultaneous coordination of both dialkylzinc reagent and aldehyde reactant. By contrast, the Soai reactants are rigid gamma-aminoaldehydes that cannot function as mononuclear chelates. Structural and computational evidence for a binuclear resting state is presented, and the energetics of mono-, di-, tri-, and tetrameric species accessible to the reacting system have been computed.