title: Hexafluoroantimonic acid catalysis: formal [3+2+2] cycloaddition of aziridines with two alkynes.
abstract: A practical method for the synthesis of azepine derivatives, a typical seven-membered heterocyclic ring system, was developed and involves the use of hexafluoroantimonic acid to catalyze a formal [3+2+2] cycloaddition of aziridines with two alkynes. This method was applicable to two of the same or different terminal alkynes for the [3+2+2] cycloaddition with unactivated aziridines, and furnished the corresponding azepine derivatives in good yields with good levels of chemo- and regioselectivity. The mechanism was also discussed according to the results of the in situ HRMS and (1)H NMR analysis.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China).
authors.forename: Ming-Bo
authors.initials: MB
authors.lastname: Zhou
authors.forename: Ren-Jie
authors.initials: RJ
authors.lastname: Song
authors.forename: Jin-Heng
authors.initials: JH
authors.lastname: Li
keywords: alkynes; aziridines; cycloaddition; heterocycles; superacidic systems