Acid-Base Dual-FunctionalCatalysis by Axially Chiral Guanidine in Enantioselective [3+2] Cycloadditionof Maleate to Schiff Bases as a Precursor of Azomethine Ylides

The enantioselective [3+2] cycloaddition reaction of dimethyl maleate with Schiff bases as the precursor of azomethine ylide was developed using axially chiral guanidine catalysts to provide optically active pyrrolidine derivatives. Acid―base dual-functional catalysis by an axially chiral guanidine through double hydrogen-bonding interaction is proposed to give the cycloaddition products in good yields.