1-Heteroaromatic-Substituted Tetraphenylboroles: π–π Interactions Between Aromatic and Antiaromatic Rings Through a B–C Bond
作者:Holger Braunschweig、Alexander Damme、J. Oscar C. Jimenez-Halla、Christian Hörl、Ivo Krummenacher、Thomas Kupfer、Lisa Mailänder、Krzysztof Radacki
DOI:10.1021/ja309935t
日期:2012.12.12
A series of 2,3,4,5-tetraphenylboroles substituted with different aromatic heterocycles (thiophene, furan, pyrrole, and dithiophene) in the 1-position were synthesized and characterized by means of NMR, elemental analysis, and X-ray crystallography. In contrast to known 2,3,4,5-tetraphenylboroles, X-ray diffraction revealed a nearly coplanar arrangement of the aromatic heterocycles and the antiaromatic borole scaffold as a result of pi-conjugation, which could be substantiated by DFT calculations. Furthermore, the 2,2'-dithiophene-bridged bisborole (14) exhibits a large bathochromic shift in the absorption spectrum, demonstrating the exceptional Lewis acidity of the nonannulated borolyl moiety.
Synthesis of the First Heteroaryl-Substituted Boryl Complexes: Strong Stabilizing Effects of Boron–Aryl π-Conjugation
作者:Holger Braunschweig、Rian D. Dewhurst、Thomas Kramer
DOI:10.1021/acs.inorgchem.5b00192
日期:2015.4.6
The first examples of heteroarylboryl complexes were prepared and have been found to be unreactive toward a range of strong reductants, strong Lewis bases, and halide-abstraction reagents. The inertness of the complexes is attributed to strong p-conjugation between the p-basic heteroaryl groups and the p-acidic boron atom. This hypothesis is supported by comparison of the structural and spectroscopic properties of the heteroarylboryl complexes with analogous previously reported homoarylboryl complexes, with the former showing greater coplanarity of the aryl ring with the boron atom and much less facile reactivity.
The carboboration of Me<sub>3</sub>Si-substituted alkynes and allenes with boranes and borocations
作者:James R. Lawson、Valerio Fasano、Jessica Cid、Inigo Vitorica-Yrezabal、Michael J. Ingleson
DOI:10.1039/c5dt03003j
日期:——
ArylBCl2and aryl and vinyl containing borocations synthesised by electrophilic borylation effect the carboboration of TMS-substituted alkynes and allenes.
Direct Hydroboration of BB Bonds: A Mild Strategy for the Proliferation of BB Bonds
作者:Holger Braunschweig、Rian D. Dewhurst、Christian Hörl、Ashwini K. Phukan、Florian Pinzner、Stefan Ullrich
DOI:10.1002/anie.201309325
日期:2014.3.17
strongly reducing reagents or transition‐metal catalysts, both with distinct disadvantages. The synthesis of new furyl‐ and thienyl‐substituted diborenes is presented, along with their direct hydroboration with catecholborane (CatBH) to form a new electron‐precise BB bond and a B3 chain. The reaction is diastereoselective and proceeds under mild conditions without the use of strong reducingagents or transition‐metal