N-bromosuccinimide - A selective, mild substitute for bromine

Abstract

(A) Chakrabarty et al. recently reported the formation of an enamide double bond under benzylic bromination conditions with NBS in a concise synthesis of coscinamide B, an anti-HIV bis-indolic enamide. (B) Oxidation of indoles to isatins has also been accomplished by NBS; the reaction is thought to proceed via a 3,3-dibromooxindole as an intermediate. Indeed, Fuchs and Funk have isolated and used a 3-alkyl-3-bromooxindole as a key intermediate in the elegant syntheses of (±)-flustramines A and C, and (±)-perphoramidine. (C) Decarboxylative bromination with NBS in the presence of LiOAc under MWI has provided a stereoselective synthesis of (E)-β-arylvinyl bromides by a Hunsdiecker-type reaction. (D) Recently, NBS was used to catalyse both hydroamination and hydroalkoxylation of activated styrenes to afford amino and ether derivatives, respectively. (E) Interestingly, NBS, along with DBU, promotes the cyclisation of N-alkylthioureidoindoles and alkyl N-(indol-5′-yl)dithiocarbamates to furnish only the corresponding 2-alkylamino- and 2-alkylthiothiazolo[5,4-e]indoles, regioselectively. (F) NBS has also found application in the oxidative cycloamination of olefins with aziridines for the synthesis of saturated nitrogen-contaning heterocycles. © Georg Thieme Verlag Stuttgart.