Recyclable BINOL-quinine-squaramide as a highly efficient organocatalyst for alpha-amination of 1,3-dicarbonyl compounds and alpha-cyanoacetates

An efficient organocatalytic asymmetric alpha-amination of 1,3-dicarbonyl and alpha-cyanoacetates compounds towards chiral alpha-amino acid precursors is reported. The enantioselective synthesis of these compounds was achieved with excellent yields and ee values (up to 99% yield and 99% ee) by treatment of 1,3-dicarbonyl compounds or alpha-cyanoacetates with azodicarboxylates in the presence of multiple hydrogen bond donor BINOL-quinine-squaramide organocatalyst 1a developed in our laboratory. The squaramide catalyst 1a can be recovered and reused for four cycles without loss of activity and enantioselectivity.