Regioselective Hydroacylation of 1,3-Dienes by Cobalt Catalysis
摘要:
We describe a cobalt-catalyzed hydroacylation of 1,3-dienes with non-chelating aldehydes. Aromatic aldehydes provide 1,4-addition products as the major isomer, while aliphatic aldehydes favor 1,2-hydroacylation products. The kinetic profile supports an oxidative cyclization mechanism involving a cobaltacycle intermediate that undergoes transformation with high regio- and stereoselectivity.
α- and β-Functionalized Ketones from 1,3-Dienes and Aldehydes: Control of Regio- and Enantioselectivity in Hydroacylation of 1,3-Dienes
作者:Mahesh M. Parsutkar、T. V. RajanBabu
DOI:10.1021/jacs.1c06245
日期:2021.8.18
oxidative dimerization mechanism that involves a Co(I)/Co(III) redox cycle that appears to be initiated by a cationic Co(I) intermediate. Studies of reactions using isolated neutral and cationic Co(I) complexes confirm the critical role of the cationic intermediates in these reactions. Enantioselective 1,2-hydroacylation of 2-trimethylsiloxy-1,3-diene reveals a hitherto undisclosed route to chiral siloxy-protected
Nickel-Catalyzed Coupling of Arylzinc Halides with Thioesters
作者:Paul H. Gehrtz、Prasad Kathe、Ivana Fleischer
DOI:10.1002/chem.201801887
日期:2018.6.21
The Pd‐catalyzed Fukuyama reaction of thioesters with organozinc reagents is a mild, functional‐group‐tolerant method for acylation chemistry. Its Ni‐catalyzed variant might be a sustainable alternative to expensive catalytic Pd sources. We investigated the reaction of S‐ethyl thioesters with aryl zinc halides with hetero‐ and homotopic Ni precatalysts and several ligands. The results show that both
Homo- and cross-coupling involving alkenyl halides have been performed efficiently using an electroassisted nickel-complex catalysis. Valuable product such as conjugated dienes, beta,gamma- or gamma,delta-unsaturated esters, ketones, or nitriles, as well as alkenylated aryl compounds are thus prepared with high yields and high stereoselectivity. Partial isomerization is only observed in a few cases, when the alkenyl halide is involved in a late step of the catalytic cycle. This is the case in the preparation of (Z,Z)-1,3-diene.
Regioselective Hydroacylation of 1,3-Dienes by Cobalt Catalysis
作者:Qing-An Chen、Daniel K. Kim、Vy M. Dong
DOI:10.1021/ja500268w
日期:2014.3.12
We describe a cobalt-catalyzed hydroacylation of 1,3-dienes with non-chelating aldehydes. Aromatic aldehydes provide 1,4-addition products as the major isomer, while aliphatic aldehydes favor 1,2-hydroacylation products. The kinetic profile supports an oxidative cyclization mechanism involving a cobaltacycle intermediate that undergoes transformation with high regio- and stereoselectivity.