User-friendly and Green Procedure for a Photoinduced Wohl-Ziegler Reaction

Abstract

A convenient Wohl-Ziegler bromination protocol using NBS under visible light in standard laboratory glassware is described. The monobromination reaction is efficient and selective over a wide range of substrates. Unlike previous studies, we prove that the use of a photocatalyst is unnecessary. The proposed protocol is simple to implement and applicable at the gram scale. The reaction takes place in a few tens of minutes at room temperature and offers an alternative to the use of CCl4, which is conventionally used for Wohl-Ziegler bromination. Alternative conditions of bromination by CBr4 in the presence of a photocatalyst have also been investigated.