A convenient 1,3-dipolar cycloaddition–reduction synthetic sequence from 2-allyloxy-5-nitro-salicylaldehyde to aminobenzopyran-annulated heterocycles
作者:Narsidas J. Parmar、Bhavesh R. Pansuriya、Balvantsingh M. Labana、Rajni Kant、Vivek K. Gupta
DOI:10.1039/c3ra42220h
日期:——
A microwave-assisted, one-pot synthesis of some nitro benzopyran-annulated pyrroles as well as pyrrolo-fused isoquinolines via a 1,3-dipolar cycloaddition, which involves the in situ generation of azomethine ylide formed by reacting secondary amines with 2-allyloxy-5-nitro-salicylaldehyde, has been achieved in a solvent-free environment. Compared to methods of conventional and thermal heating, the present microwave-assisted method is rapid and highly efficient. In addition, amino analogous heterocycles were successfully accessed after treating the reaction mass further with iron in acidic medium, which also highlights a one-pot procedure for a new 1,3-dipolar cycloadditionâreduction synthetic sequence. All amino-products are new bioprofiles and anticipated to be effective drug-like candidates. All compounds were characterised based on their elemental analysis, mass, IR, and 1H and 13C NMR spectroscopic data. The stereochemistry of the product was confirmed by 2D NMR COSY and NOESY experiments, which, on the basis of single crystal X-ray diffraction data analysis, was further confirmed and supported.