Efficient Cu(OTf)2-catalyzed and microwave-assisted rapid synthesis of 3,4-fused chromenopyridinones under neat conditions

An efficient, solvent-free, environmentally benign, Cu(OTf)(2)-catalyzed and microwave-assisted fast synthesis of a fascinating class of a number of angularly fused chromenopyridinones having a carboxylate group at C-2 position on the pyridine ring via a one-pot [3+3] annulation reaction of several aminocoumarins/cyclic beta-enaminones with different kinds of gamma-aryI/styryI/heteroaryl-substituted-beta,gamma-unsaturated alpha-ketoesters as Michael acceptors under open atmosphere. This eco-friendly method delivers good to excellent yields of pyridine-fused-heterocycles within (15-40 min) without using any traditional oxidants and allows several important functionalities. Furthermore, by this method, stereos elective synthesis of trans-7,8-diaryl-8.9-dihydrochromeno[4,3-b]cyclopenta[e]pyridine-6,10-diones were obtained in an excellent diastereoselective manner (dr <= 99:1). (C) 2017 Elsevier Ltd. All rights reserved.