Oxidative annulations via double CH bond cleavages: Approach to quinoline derivatives
作者:Zhenghui Liu、Shien Guo、Peng Wang、Zhenzhong Yan、Tiancheng Mu
DOI:10.1002/aoc.6156
日期:2021.4
system via oxidative annulations was proposed. A systematic exploration was completed. All kinds of reaction parameters were determined. And 55 kinds of target molecules were obtained with moderate to high yields. Combination of double oxidants made the conversion proceed smoothly. A clear reaction mechanism was put forward. Adjacent π systems might provide assistance for realizing the activation of relatively
An iron-catalyzed cyclization of hydroxy allylic derivatives into tetrahydropyrans possessing an N-heteroaryl at C2 is disclosed. The reaction proceeds with good yield and in high diastereoselectivity in favor of the more stable isomer. The diastereoselectivity results from an iron-induced reopening of the tetrahydropyrans, allowing a thermodynamic equilibration. The method allows access to a variety of 2,6-disubstituted as well as 2,4,6-trisubstituted tetrahydropyrans that could be considered as attractive scaffolds for the pharmaceutical industry.
Lewis Basicity Modulation of <i>N</i>-Heterocycles: A Key for Successful Cross-Metathesis
Cross-metathesis involving N-heteroaromatic olefinic dervatives is disclosed. The introduction of an appropriate substitutent on the heteroaromatic ring decreases the lewis basicity of the nitrogen atom, thus preventing the deactivation of the ruthenium-centered catalyst. The reaction is quite general in terms of both N-heterocycles and olefinic partners.
Rhodium(III)-Catalyzed Direct Selective C(5)–H Oxidative Annulations of 2-Substituted Imidazoles and Alkynes by Double C–H Activation
Double C-H activations of C(5)-H and Csp(2)-H of 2-substituted N-vinyl- or arylimidazoles were realized without heteroatom-directing assistance by rhodium(III) catalyst. A subsequent oxidative annulation reaction with alkynes efficiently produced aza-fused heterocycles with high molecular complexity in low to excellent yields.