Iridium‐Catalyzed Regio‐ and Enantioselective Borylation of Unbiased Methylene C(sp
<sup>3</sup>
)−H Bonds at the Position β to a Nitrogen Center
作者:Rongrong Du、Luhua Liu、Senmiao Xu
DOI:10.1002/anie.202016009
日期:2021.3.8
pyrazole‐directed iridium‐catalyzedenantioselectiveborylation of unbiased methylene C−H bonds at the position β to a nitrogen center. The combination of a chiral bidentate boryl ligand, iridium precursor, and pyrazole directing group was responsible for the high regio‐ and enantioselectivity observed. The method tolerated a vast array of functional groups to afford the corresponding C(sp3)−H functionalization
N-(hydroxyalkyl)pyrazoles and borane formed boric ester complex, in which the remaining borane was stabilized by the adjacent nitrogen of thr pyrazole ring. The borane complex derived from the chiral pyrazoles such as 3-phenyl-l-menthopyrazole reduced p-methylacetophenone (21) enantioselectively. When (2′S)-2-(2′-phenyl-2′-hydroxyethyl)-3-phenyl-l-menthopyrazole ((2′S)-10b) was used, 21 was reduced into (
An efficient synthesis of β-hydroxyethylpyrazoles from propylene and styrene oxide using Cs 2 CO 3
作者:Virginie Duprez、Andreas Heumann
DOI:10.1016/j.tetlet.2004.05.124
日期:2004.7
Bases such as caesium carbonate efficiently catalyze the regioselective ring opening of propylene and styrene oxide with various substituted pyrazoles. (C) 2004 Elsevier Ltd. All rights reserved.
Kaur, Kamalneet; Kumar, Vikas; Kumar, Vinod, Indian Journal of Heterocyclic Chemistry, 2018, vol. 28, # 1, p. 153 - 162