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Aluminium‐Catalyzed C(sp)−H Borylation of Alkynes
Author(s) -
Willcox Dominic R.,
De Rosa Daniel M.,
Howley Jack,
Levy Abigail,
Steven Alan,
Nichol Gary S.,
Morrison Carole A.,
Cowley Michael J.,
Thomas Stephen P.
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202106216
Subject(s) - borylation , alkyne , chemistry , reactivity (psychology) , hydroboration , medicinal chemistry , alkene , catalysis , metathesis , ligand (biochemistry) , hydride , intramolecular force , aryl , alkyl , organic chemistry , polymerization , medicine , hydrogen , biochemistry , alternative medicine , polymer , receptor , pathology
Historically used in stoichiometric hydroalumination chemistry, recent advances have transformed aluminium hydrides into versatile catalysts for the hydroboration of unsaturated multiple bonds. This catalytic ability is founded on the defining reactivity of aluminium hydrides with alkynes and alkenes: 1,2‐hydroalumination of the unsaturated π‐system. This manuscript reports the aluminium hydride catalyzed dehydroborylation of terminal alkynes. A tethered intramolecular amine ligand controls reactivity at the aluminium hydride centre, switching off hydroalumination and instead enabling selective reactions at the alkyne C−H σ‐bond. Chemoselective C−H borylation was observed across a series of aryl‐ and alkyl‐substituted alkynes (21 examples). On the basis of kinetic and density functional theory studies, a mechanism in which C−H borylation proceeds by σ‐bond metathesis between pinacolborane (HBpin) and alkynyl aluminium intermediates is proposed.