A remarkable solvent effect on the reaction of 4-hydroxycoumarin with (E)-3-aryl-2-nitroprop-2-enol: Facile synthesis of highly substituted furo/pyrano[3,2-c]chromenes

Abstract

A remarkable solvent effect on the reaction of 4-hydroxycoumarin derivatives with (E)-3-aryl/hetero-aryl-2-nitroprop-2-enols has been observed in water and DMSO media. This result was employed for the straightforward syntheses of new functionalized furo/pyrano[3,2-c]chromenes in 63–93% yields and diasteromeric ratio up to ≤99 : 1. Moreover, a simple, mild, efficient and catalyst-free one-pot method may offer an alternative synthetic strategy for annulating the furan/pyran rings on the coumarin nucleus. Furthermore, water has shown a significant positive effect on the rate and selectivity (product) of this reaction.