Bromination of 2,3-dihydrobenzobarrelene and synthesis of its mono- and dibromide derivatives: unexpected Wagner-Meerwein rearrangement on silica gel

Authors: SELÇUK EŞSİZ, MEHMET EMİN ŞENGÜL, ERTAN ŞAHİN, ARİF DAŞTAN

Abstract: The bromination reaction of dihydrobenzobarrelene under different conditions was studied. The bromination reaction of dihydrobenzobarrelene with molecular bromine gave only a Wagner-Meerwein rearrangement product by aryl and alkyl migration. Its high-temperature bromination reaction resulted in the formation of normal addition products besides rearrangement products. The bromination reaction of the alkene with 1,2- dibromotetrachloroethane (DBTCE) gave a non-rearrangement product as the sole product. The synthesis and bromination reaction of 2-bromodihydrobenzobarrelene was also studied. An unexpected Wagner-Meerwein rearrangement was observed on silica gel during the column chromatography of isomeric tribromides. Herein, we report the results of the synthesis, and the X-ray crystal structures and the possible mechanism of processes are discussed.

Keywords: Bromination, benzobarrelene, Wagner-Meerwein rearrangement

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