Synthesis of 3-heteroarylchromones via a photochemical reaction.

The direct coupling of 3-iodochromen-4-ones with heteroaromatics has been achieved via a photochemical reaction. A variety of 3-heteroarylchromones was obtained in moderate to good yields from the corresponding 3-iodochromen-4-ones and heteroaromatics, such as pyrrole, furan, thiophene, and benzofuran. The reaction worked smoothly in acetonitrile under a mercury lamp without any additives, providing a catalyst- and base-free approach for the synthesis of 3-heteroarylchromones.