L-Ascorbic Acid; A Green and Competent Promoter for Solvent-Free Synthesis of Flavones and Coumarins under Conventional as well as Microwave Heating

摘要

Background: An expeditious approach has been developed for the synthesis of two distinct classes of benzopyrones viz. flavones and coumarins under solvent-free conditions. L-Ascorbic acid was found to be an effective promoter under microwave irradiation and conventional heating. Various benzo-alpha-pyrones and benzo-gamma-pyrones were synthesized with overall good yields. The present protocol is highly facile and needs no column chromatography for purification and therefore it would serve as an effective and compatible method under both microwave irradiation and conventional heating.