One-pot synthesis of polycyclic heterocyclic compounds by condensation of 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium salts with pyridine-2, 3, and 4-and quinoline-4-carboxaldehydes

摘要

A one-pot synthesis of new polycyclic heterocyclic compounds was carried out via the condensation of 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium chloride with pyridine- and quinolinecarboxaldehydes. The heating of the aforementioned 3H-indolium salts with 1 eq. of pyridine-2, 3, and 4- or quinoline-4-carboxaldehyde in ethanol in the presence of piperidine as a catalyst provided 9a-12(pyridyl)ethenyll- or 9a-[2-(quinolyl)ethenyl]-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-one derivatives as the main products. However, reaction outcome was dramatically different for the analogous reactions in acetic acid. In this case, the heating of the chloride with 2 eq. of pyridine-2-carboxaldehyde afforded derivatives of 9a-[3-(pyridin-2-yl)indolizin-2-yl]-9,9a-dihydro-1H-imidazo [1,2-a]indol-2(3H)-one as the major product, while the use of 2 eq. of pyridine-3 and 4- or quinoline-4-carboxaldehyde led to the formation 2-heteroaryl-1-heteroarylmethyl-9H-pyrrolo[1,2-a]indole-3-carboxamides. Plausible pathways for the cyclization reactions are discussed. The structural assignments were based on H-1, C-13 and N-15 NMR spectroscopy, HRMS and single-crystal X-ray diffraction data. (C) 2018 Elsevier Ltd. All rights reserved.