An approach to the selenobromination of aryl(thienyl)alkynes: Access to 3-bromobenzo[b]selenophenes and selenophenothiophenes

Article abstract of DOI:10.1002/ejoc.201402095

A novel approach for the cyclization of arylalkynes with selenium(IV) bromide prepared in situ has been elaborated. The use of an alkene additive as a bromine scavenger provides a convenient synthetic pathway for the synthesis of a wide variety of 3-bromobenzo[b]selenophenes. Reactions can be performed open to air without the use of moisture-sensitive reagents, anhydrous solvents, or an inert atmosphere. Selenobromination of ethynylthiophenes has been applied for the preparation of selenopheno[3,2-b]- and selenopheno[2,3-b]thiophenes. The molecular structures of representative derivatives have been confirmed by X-ray crystallographic analysis. The use of an alkene additive as a bromine scavenger under selenobromination conditions provides a convenient synthetic pathway for the synthesis of a wide variety of 3-bromobenzo[b]selenophenes in moderate to high yields. The reactions are not moisture-sensitive and do not require an inert atmosphere. Selenobromination of ethynylthiophenes enables the preparation of selenopheno[b]thiophenes. Copyright