One-pot synthesis of novel pyranocoumarins using 7-hydroxy 4-methyl-6-nitro coumarins, acetylenic esters and isocyanides

Coumarins form an exceptional class of oxygen containing heterocyclic compounds, which exhibit significant biological activities, such as inhibitory of platelet aggregation [1], 1,2 inhibitory of steroid 5α-reductase, inhibitory of HIV-1 protease [2], antibacterial and anticancer activities [3]. In continuation of our general interest in the synthesis of heterocyclic compounds via three-component reactions, we have investigated the reactions of 7-hydroxy 4-methyl-6-nitro coumarins with acetylenic esters and isocyanides in tetrahydrofuran (THF) that afford the novel pyranocoumarins to high yields. The structures of the products were determined by 1H, 13C NMRand IR spectroscopy as well as mass spectrometry.