An Efficient Preparation of Chroman Derivatives from 3-Aryl-1-propanols and Related Compounds with 1,3-Diiodo-5,5-dimethylhydantoin under Irradiation Conditions

Treatment of various 3-aryl-1-propanols with 1,3-diiodo-5,5-dimethylhydantoin (DIH) in ethyl acetate or 1,2-dichloroethane under irradiation with a tungsten lamp gave the corresponding chroman derivatives in good to moderate yields. The present reaction proceeds via the initial formation of an alkoxyl radical and the radical cyclization onto the aromatic ring, followed by the oxidation of the formed radical intermediate with DIH to provide the chroman derivative. The same treatment of o-biphenyldimethylcarbinol, o-phenylbenzoic acid, and o-alkylbenzoic acids with DIH provided the corresponding chroman derivatives and lactone derivatives in good yields, respectively.