Smooth photocatalytic preparation of 2-substituted 1,3-benzodioxoles

A mild and general method for the synthesis of potentially bioactive 2‐substituted‐1,3‐benzodioxoles is presented. This is based on the photocatalyzed activation of methylene hydrogen atoms in the presence of tetrabutylammonium decatungstate (TBADT). The method gave yields ranging from 46–77 % with no interference by benzene ring substituents, such as OR, COOMe, Me, or CHO. The OH group interfered, but protection regenerated the reactivity. 5‐Chloro‐1,3‐benzodioxole was converted into a safrole derivative through a one‐pot process involving two consecutive irradiations, at 366 nm for the photocatalyzed alkylation at position 2 and at 310 nm for the alkylation at position 5.