Photooxidative cyclization of 3-aryl/heteroaryl-4-heteroaryl coumarins: An experimental and semi-empirical study

Abstract

Photochemical oxidation of substituted coumarins 1, 3 and 5 in benzene solution containing iodine gave the respective products 2, 4 and 6. The structures of the photoproducts have been confirmed by analyses of analytical and spectral data. The experimental results are further strengthened by their agreement with computationally calculated dipole moments (μ), minimum-energy values and heats of formations.