title: Haloboration of internal alkynes with boronium and borenium cations as a route to tetrasubstituted alkenes.
abstract: Hail boration! 2-Dimethylaminopyridine-ligated dihaloborocations [X2B(2-DMAP)](+) with a strained four-membered boracycle were used for the haloboration of terminal and dialkyl internal alkynes (see scheme). Esterification then provided vinyl boronate esters as useful precursors to tetrasubstituted alkenes. Following mechanistic studies, the scope of the haloboration was expanded simply by variation of the amine. Pin = 2,3-dimethyl-2,3-butanedioxy.
authors.affiliation: School of Chemistry, University of Manchester, Manchester, M13 9PL, UK.
authors.forename: James R
authors.initials: JR
authors.lastname: Lawson
authors.forename: Ewan R
authors.initials: ER
authors.lastname: Clark
authors.forename: Ian A
authors.initials: IA
authors.lastname: Cade
authors.forename: Sophia A
authors.initials: SA
authors.lastname: Solomon
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ingleson
keywords: borenium ions; boronate esters; haloboration; synthetic methods; tetrasubstituted alkenes