Parahydrogen‐Induced Polarization in Hydrogenation Reactions Mediated by a Metal‐Free Catalyst
作者:Danila O. Zakharov、Konstantin Chernichenko、Kristina Sorochkina、Shengjun Yang、Ville‐Veikko Telkki、Timo Repo、Vladimir V. Zhivonitko
DOI:10.1002/chem.202103501
日期:2022.2.7
products was observed in alkyne hydrogenations with parahydrogen mediated by a metal-free hydroborane catalyst. The observed effects are unusual, as the mechanism of the reaction is not pairwise, thus allowing hyperpolarization of only one of two protons at double bonds. Moreover, this enabled various important intermediates to be characterized by hyperpolarized 1H, 11B and 15N NMR spectroscopy.
在无金属氢硼烷催化剂介导的仲氢炔烃氢化反应中,观察到烯烃产物中核自旋的显着超极化。观察到的效果是不寻常的,因为反应机制不是成对的,因此仅允许双键处两个质子中的一个超极化。此外,这使得各种重要的中间体能够通过超极化1 H、 11 B 和15 N NMR 光谱进行表征。
Hydrogen activation by 2-boryl-N,N-dialkylanilines: a revision of Piers’ ansa-aminoborane
Two 2-[bis(pentafluorophenyl)boryl]-N,N-dialkylanilines reported here exemplify a new class of intramolecular frustrated B/N Lewis pairs. A structure closely related to this class structure was synthesized in 2003 by Piers et al. but was unable to activate H2. The new aminoboranes can activate hydrogen at near ambient conditions; besides, one of them can hydrogenate imines and enamines in a catalytic fashion demonstrating the validity of the original Piersâ approach to hydrogen activation with ansa-aminoboranes.
and have been shown to be capable of heterolysis of molecular hydrogen, a property that has led to their use in hydrogenation reactions of polarized multiple bonds. Here, we describe a general approach to the hydrogenation of alkynes to cis-alkenes under mild conditions using the unique ansa-aminohydroborane as a catalyst. Our approach combines several reactions as the elementary steps of the catalytic