TY  - INPR
A1  - Hermann, Alexander
A1  - Arrowsmith, Merle
A1  - Trujillo-Gonzalez, Daniel
A1  - Jiménez-Halla, J. Oscar C.
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Trapping of a Borirane Intermediate in the Reductive Coupling of an Arylborane to a Diborene
T2  - Journal of the American Chemical Society
N2  - The reductive coupling of an NHC-stabilized aryldibromoborane yields a mixture of trans- and cis-diborenes in which the aryl groups are coplanar with the diborene core. Under dilute reduction conditions two diastereomers of a borirane-borane intermediate are isolated, which upon further reduction give rise to the aforementioned diborene mixture. DFT calculations suggest a mechanism proceeding via nucleophilic attack of a dicoordinate borylene intermediate on the aryl ring and subsequent intramolecular B-B bond formation.
KW  - boron
KW  - reactive intermediates
KW  - reductive coupling
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203140
N1  - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/jacs.0c02306
ER  - 
TY  - JOUR
A1  - Böhnke, Julian
A1  - Brückner, Tobias
A1  - Hermann, Alexander
A1  - González-Belman, Oscar F.
A1  - Arrowsmith, Merle
A1  - Jiménez-Halla, J. Oscar C.
A1  - Braunschweig, Holger
T1  - Single and double activation of acetone by isolobal B≡N and B≡B triple bonds
JF  - Chemical Science
N2  - B≡N and B≡B triple bonds induce C-H activation of acetone to yield a (2-propenyloxy)aminoborane and an unsymmetrical 1-(2- propenyloxy)-2-hydrodiborene, respectively. DFT calculations showed that, despite their stark electronic differences, both the B≡N and B≡B triple bonds activate acetone via a similar coordination-deprotonation mechansim. In contrast, the reaction of acetone with a cAAC-supported diboracumulene yielded a unique 1,2,3-oxadiborole, which according to DFT calculations also proceeds via an unsymmetrical diborene, followed by intramolecular hydride migration and a second C-H activation of the enolate ligand.
KW  - acetone
KW  - diborynes
KW  - iminoboranes
KW  - boron
KW  - small-molecule activation
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164286
VL  - 9
ER  - 
TY  - JOUR
A1  - Auerhammer, Dominic
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian D.
A1  - Jiménez-Halla, J. Oscar C.
A1  - Kupfer, Thomas
T1  - Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor
JF  - Chemical Science
N2  - The reaction of [(cAAC\(^{Me}\))BH\(_{3}\)] (cAAC\(^{Me}\) = 1-(2,6-iPr\(_{2}\)C\(_{6}\)H\(_{3}\))-3,3,5,5-tetramethylpyrrolidin-2-ylidene) with a range of organolithium compounds led to the exclusive formation of the corresponding (dihydro)organoborates, Li\(^{+}\)[(cAAC\(^{Me}\)H)BH\(_{2}\)R]− (R = sp\(^{3}\)-, sp\(^{2}\)-, 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, [(cAAC\(^{Me}\)H)BH\(_{2}\)R]− (R]. Similarly the reaction of [cAAC\(^{Me}\))BH\(_{3}\)] with a neutral donor base L resulted in adduct formation by shuttling one boron-bound hydrogen to the cAAC ligand, to generate [(cAAC\(^{Me}\)H)BH\(_{2}\)L], either irreversibly (L = cAAC\(^{Me}\)) or reversibly (L = pyridine). Variable-temperature NMR data and DFT calculations on [(cAAC\(^{Me}\)H)BH\(_{2}\)(cAAC\(^{Me}\))] show that the hydrogen on the former carbene carbon atom exchanges rapidly with the boron-bound hydrides.
KW  - nucleophilic addition
KW  - nucleophilic substitution
KW  - boron-bound hydrogen
KW  - carbene donor
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170255
VL  - 8
IS  - 10
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Dömling, Michael
A1  - Schmidt, Uwe
A1  - Werner, Luis
A1  - Castro, Abril C.
A1  - Jiménez-Halla, J. Oscar C.
A1  - Müssig, Jonas
A1  - Prieschl, Dominic
A1  - Braunschweig, Holger
T1  - Spontaneous trans‐Selective Transfer Hydrogenation of Apolar B=B Double Bonds
T2  - Angewandte Chemie, International Edition
N2  - The transfer hydrogenation of NHC-supported diborenes with dimethylamine borane proceeds with high selectivity for the trans-1,2-dihydrodiboranes(6). DFT calculations suggest a stepwise proton-first-hydride-second reaction mechanism via an intermediate μ-hydrodiboronium dimethylaminoborate ion pair.
KW  - transfer hydrogenation
KW  - diborene
KW  - amine borane dehydrocoupling
KW  - diboranes
KW  - DFT mechanism
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184874
N1  - This is the pre-peer reviewed version of the following article: M. Dömling, M. Arrowsmith, U. Schmidt, L. Werner, A. C. Castro, J. O. C. Jiménez-Halla, R. Bertermann, J. Müssig, D. Prieschl, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 9782. doi:10.1002/anie.201902656, which has been published in final form at  https://doi.org/10.1002/anie.201902656. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  -