Nucleophilic Additions to Pyridium Salts. Reduction of the Intermediate Dihydropyridines

Article abstract of DOI:10.1016/S0040-4020(01)90433-8

Reduction of indolyldihydropyridines 4 and 5 satisfactorily gave the corresponding tetrahydropyridines 6 and 7.A similar reduction of 4-(2-indolylmethyl)-1,4-dihydropyridines 3 was inefficient.In contrast, dihydropyridine 19 was reduced to 23 and then cyclized to pentacycle 24.Direct cyclization of 19 resulted in the formation of imide 21.