Issue 10, 2017

Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor

Abstract

The reaction of [(cAACMe)BH3] (cAACMe = 1-(2,6-iPr2C6H3)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) with a range of organolithium compounds led to the exclusive formation of the corresponding (dihydro)organoborates, Li+[(cAACMeH)BH2R] (R = sp3-, sp2-, or sp-hybridised organic substituent), by migration of one boron-bound hydrogen atom to the adjacent carbene carbon of the cAAC ligand. A subsequent deprotonation/salt metathesis reaction with Me3SiCl or spontaneous LiH elimination yielded the neutral cAAC-supported mono(organo)boranes, [(cAACMe)BH2R]. Similarly the reaction of [(cAACMe)BH3] with a neutral donor base L resulted in adduct formation by shuttling one boron-bound hydrogen to the cAAC ligand, to generate [(cAACMeH)BH2L], either irreversibly (L = cAACMe) or reversibly (L = pyridine). Variable-temperature NMR data and DFT calculations on [(cAACMeH)BH2(cAACMe)] show that the hydrogen on the former carbene carbon atom exchanges rapidly with the boron-bound hydrides.

Graphical abstract: Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor

Supplementary files

Article information

Article type
Edge Article
Submitted
21 Jul 2017
Accepted
01 Aug 2017
First published
04 Aug 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2017,8, 7066-7071

Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor

D. Auerhammer, M. Arrowsmith, H. Braunschweig, R. D. Dewhurst, J. O. C. Jiménez-Halla and T. Kupfer, Chem. Sci., 2017, 8, 7066 DOI: 10.1039/C7SC03193A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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