Cs2CO3-I2 Promoted Efficient Synthesis of Flavones and Flavanones: Total Synthesis of Narengenin and Apigenin

Abstract

Flavonoids are an important class of naturally existing scaffolds known for their diverse biological activities and have been immensely synthesized using stoichiometric reagent amounts. Herein, we report a reliable, robust, one-pot, transition metal and additive-free protocol for the synthesis of flavones and flavanones from 2-hydroxyacetophenone and substituted aldehydes. Our developed method utilizes Cs₂CO₃ as a base and iodine as an oxidant in H₂O: DMSO (9 : 1) solvent system, which provides direct access to many flavones and flavanones in excellent yields under milder reaction conditions with simple yet easily available substrates. In application, naturally occurring compounds such as naringenin and apigenin have been successfully synthesized using developed protocol.