DMF-Assisted Radical Cyclization of o -Isocyanodiaryl Ethers via 1,5-Aryl Migration: Construction of 2-Arylbenzoxazoles.

A novel DMF-assisted radical cyclization of o -isocyanodiaryl ethers via 1,5-aryl migration has been developed for the synthesis of a series of 2-arylbenzoxazoles by the FeCl 3 /TBHP/Et 3 N catalytic system in DMF. However, N,N -dimethylbenzo[ d ]thiazole-2-carboxamide and N,N -dimethylbenzo[ d ]selenazole-2-carboxamide were obtained from the corresponding substrate 2-isocyanophenyl p -methoxyphenyl thioether and 2-isocyanodiphenyl selenoether under the same conditions. A possible mechanism may involve aryl 1,5-migration and DMF-assisted radical cyclization of o -isocyanodiaryl ethers.