Rongalite as a C1 Source for the Modular Synthesis of Methylene-Bridged Bis-chromones and 3-Substituted Methylchromones

Substantial progress has been made in the synthesis of 3-substituted methylchromones; however, a modular and versatile approach that enables rapid diversification from a single C1 source remains elusive. Herein, we report an efficient and modular approach to the synthesis of both methylene-bridged bis-chromones and 3-substituted methylchromones by using rongalite as a C1 source. Notably, this method enables the rapid and modular construction of a series of methylene-bridged bis-chromones, 3-aminomaleimidyl-, 3-azido-, and 3-arylsulfonyl-substituted methylchromones, as well as the further derivatization into methylene-bridged bis-pyrimidines. The reaction features high efficiency, broad substrate scope, and practical utility, including scale-up synthesis and product transformation into heterocyclic skeletons, demonstrating the versatility of rongalite as a C1 building block.