title: Regioselective Amine-Borane Cyclization: Towards the Synthesis of 1,2-BN-3-Cyclohexene by Copper-Assisted Triazole/Gold Catalysis.
abstract: The combination of triazole/gold (TA-Au) and Cu(OTf)2 is identified as the optimal catalytic system for promoting intramolecular hydroboration for the synthesis of a six-membered cyclic amine-borane. Excellent yields (up to 95 %) and regioselectivities (5-exo vs. 6-endo) were achieved through catalyst control and sequential dilution. Good functional-group tolerance was attained, thus allowing the preparation of highly functionalized cyclic amine-borane substrates, which could not be achieved using other methods. Deuterium-labeling studies support the involvement of a hydride addition to a gold-activated alkyne with subsequent C-B bond formation.
authors.affiliation: Department of Chemistry, University of South Florida, Tampa, FL, 33620, USA.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Motika
authors.affiliation: Department of Chemistry, West Virginia University, Morgantown, WV, 26505, USA.
authors.forename: Qiaoyi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Chemistry, West Virginia University, Morgantown, WV, 26505, USA.
authors.forename: Novruz G
authors.initials: NG
authors.lastname: Akhmedov
authors.affiliation: Department of Chemistry, University of South Florida, Tampa, FL, 33620, USA.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Wojtas
authors.affiliation: Department of Chemistry, University of South Florida, Tampa, FL, 33620, USA. xmshi@usf.edu.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Shi
keywords: boranes; copper; gold; heterocycles; reaction mechanisms