Alkene insertion reactivity of a o-carboranyl-substituted 9-borafluorene. Issue 25 (10th June 2022)

• Record Type: Journal Article
• Authors: Bischof, Tobias; Guo, Xueying; Krummenacher, Ivo; Beßler, Lukas; Lin, Zhenyang; Finze, Maik; Braunschweig, Holger
• Is Part Of: Chemical science. Volume 13:Issue 25(2022)
• Page Start: 7492
• Page End: 7497
• Publication Date: 2022-06-10
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2sc02750j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : A 9-carboranyl-substituted 9-borafluorene is reported, which is capable of undergoing efficient ring expansion to 6, 7-dihydroborepins by a previously unknown alkene insertion. Abstract : The synthesis of 9-borafluorene with an electron-withdrawing o -carboranyl substituent and its reactions with a series of alkenes are described. The o -carboranyl substituent is bonded via one of the cluster carbon atoms to the boron atom of the 9-borafluorene moiety. In all cases, the reactions afford partly saturated analogs of borepins ( i.e. 6, 7-dihydroborepins) by unprecedented alkene insertion into the endocyclic B–C bond of the borole ring. Comparative studies with 9-bromo-9-borafluorene illustrate the superior insertion reactivity of the carboranyl-substituted derivative. A suite of experimental and computational techniques disclose the unique properties of the 9-borafluorene and provide insight into how the 9-carboranyl substituent affects its chemical reactivity.