Chromones are important structural subunits in many natural products and biologically active compounds. Therefore, methods to synthesize or functionalize this structural motif are of high interest. The Wang and Wu group recently published their work where DMSO/I2 facilitates the three-component synthesis of chromones containing a thiomethyl group at the 3-position (3 in Table 1).1 This adds to the growing number of methods whereby heterocyclic annulation reactions are mediated by DMSO/I2.2,3
Their method (optimized conditions) is shown in Table 1. Using 2-hydroxyacetophenones 1, Rongalite (2, an inexpensive reagent widely used in industry), and DMSO (in blue), a variety of 3-thiomethyl chromones were synthesized in good yield. This synthesis is one-pot, simple, and requires no metal catalyst or harsh reagents. Therefore, this route is tolerant of a variety of functional groups and substitution patterns.