Phosphine-Catalyzed Sequential Michael Addition between α-Aminonitriles and Methyl Acrylate for Cyclization: Synthesis of N-Aryl-Substituted Pyrrolidines

N-Aryl-substituted pyrrolidine derivatives were synthesized via tributylphosphine-catalyzed sequential Michael addition of α-aminonitriles and methyl acrylate as starting materials. The first Michael addition between α-aminonitrile and methyl acrylate occurred mainly with Lewis base catalysts such as PBu3, DBU, and DABCO, but the subsequent Michael addition happened only with phosphine catalysts like PBu3. Furthermore, pyrrolidine derivatives were obtained from the corresponding aldehydes, amines, trimethylsilyl cyanide, and methyl acrylate through a multicomponent tandem reaction.