L-proline catalyzed an efficient multicomponent one-pot synthesis of poly substituted pyridines

A series of poly substituted pyridines (3,11-disubstituted-7-aryl-5,6,8,9-tetrahydrodibenzo[c,h]acridines) were synthesized by the multicomponent condensation of 6-substituted-1-tetralone, aromatic aldehydes and ammonium acetate in ethanol using L-proline as an efficient organocatalyst. This methodology is mild, efficient, high yielding and the catalyst is inexpensive, easily recovered from the reaction mixture and reused for five times without losing its activity.