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The Reactivities of Iminoboranes with Carbenes: BN Isosteres of Carbene–Alkyne Adducts
Author(s) -
Braunschweig Holger,
Ewing William C.,
Geetharani K.,
Schäfer Marius
Publication year - 2015
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.201409699
Subject(s) - carbene , adduct , chemistry , intramolecular force , isopropyl , lewis acids and bases , medicinal chemistry , imine , bicyclic molecule , alkyl , stereochemistry , organic chemistry , catalysis
Abstract The first examples of adducts of cyclic alkyl(amino) carbenes (CAAC) and N‐heterocyclic carbenes (NHCs) with iminoboranes have been synthesized and isolated at low temperature (−45 °C). The adducts show short BN bonds and planarity at boron, mimicking the structures of the isoelectronic imine functionality. When di‐ tert ‐butyliminoborane was reacted with 1,3‐bis(isopropyl)imidazol‐2‐ylidene (IPr), the initially formed Lewis acid–base adduct quickly rearranged to form a new carbene substituted with an aminoborane at the 4‐position. Warming the iminoborane–CAAC adduct to room temperature resulted in an intramolecular cyclization to give a bicyclic 1,2‐azaborilidine compound.