Iminopyridine Oxazoline Iron Catalyst for Asymmetric Hydroboration of 1,1-Disubtituted Aryl Alkenes
作者:Jianhui Chen、Tuo Xi、Zhan Lu
DOI:10.1021/ol503282r
日期:2014.12.19
The highly regio- and enantioselective iron-catalyzed anti-Markovnikov hydroboration of 1,1-disubstitutedarylalkenes is reported by using a novel chiral iminopyridine oxazoline (IPO) ligand, in which the iminopyridine group is proposed to stabilize the iron and chiral oxazoline group to control enantioselectivity. This distinct class of reactive IPO ligands will likely be of high value for a large
NHC-Cu-Catalyzed Enantioselective Hydroboration of Acyclic and Exocyclic 1,1-Disubstituted Aryl Alkenes
作者:Rosa Corberán、Nicholas W. Mszar、Amir H. Hoveyda
DOI:10.1002/anie.201102398
日期:2011.7.25
Tough nut to crack: Chiral bidentate N‐heterocyclic carbene copper complexes were designed that promote enantioselectivehydroborations of one of the most difficult substrate classes: acyclic and exocyclic 1,1‐disubstituted alkenes undergo reaction with >98 % site selectivity, in up to >98 % yield and e.r=96.5:3.5 (see scheme, B2(pin)2 = bis(pinacolato)diboron).
Cobalt-Catalyzed Enantioselective Hydroboration of 1,1-Disubstituted Aryl Alkenes
作者:Lei Zhang、Ziqing Zuo、Xiaolong Wan、Zheng Huang
DOI:10.1021/ja5093908
日期:2014.11.5
We report the synthesis of cobalt complexes of novel iminopyridine-oxazoline (IPO) ligands and their application to the asymmetric hydroboration of 1,1-disubstitutedarylalkenes. The new catalysts afforded α-alkyl-β-pinacolatoboranes with exclusive regioselectivity in high yields with up to 99.5% ee. Furthermore, we have applied this method to an efficient synthesis of naproxen.
A mild and efficient approach for highly regio- and enantioselective copper-catalyzed hydroboration of 1,1-diaryl substituted alkenes with bis(pinacolato)diboron (B2Pin2) was developed for the first time, providing facile access to a series of valuable β,β-diaryl substituted boronic esters with high enantiomeric purity. Moreover, this approach could also be suitable for hydroboration of α-alkyl styrenes