Enantioselective Photochemical Synthesis of a β-Lactam via the Solid State Ionic Chiral Auxiliary Method

Abstract Photolysis of crystals of a carboxylic acid-containing N,N-dialkylarylglyoxylamide to which an optically pure ammonium ion (the ionic chiral auxiliary) has been attached through a salt bridge leads to a 91 % isolated yield of a β-lactam in greater than 99 % enantiomeric excess. Suspension of the crystals in hexane allows the photoreaction to be carried out on a 500 mg scale, thus demonstrating the synthetic utility of the solid state ionic chiral auxiliary approach to asymmetric synthesis.