Mannich condensations of activated cyclic enamines

The synthesis of Mannich compounds starting from activated enamines, i.e., 2-nitromethylene-pyrrolidine and pyrrolidin-2-ylidene-acetic acid ethyl ester, with various amines and formaldehyde or ethyl glyoxylate are described. In order to furnish new Mannich type molecules and to improve the yields sequential reaction routes and 1,2,3-benzotriazole-substituted adducts as reactants were also tested. Additionally, the steric structure of a tricyclic spiro compound formed unexpectedly in high yield was elucidated in details by modern NMR methods.