Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
作者:Lixing Zhao、Chenyang Hu、Xuefeng Cong、Gongda Deng、Liu Leo Liu、Meiming Luo、Xiaoming Zeng
DOI:10.1021/jacs.0c12318
日期:2021.1.27
Transition metal catalysis that utilizes N-heterocycliccarbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for
Catalytic constructive deoxygenation of lignin-derived phenols: new C–C bond formation processes from imidazole-sulfonates and ether cleavage reactions
作者:Stuart M. Leckie、Gavin J. Harkness、Matthew L. Clarke
DOI:10.1039/c4cc04939j
日期:——
feedstock for less oxygenated fine chemicals, several catalytic C-Cbond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxygenation on a benzoxazole functionalised anisole.
A highly diastereo- and enantioselective nitro-Mannich reaction of isatin-derived ketimines with α-aryl nitromethane catalyzed by Cinchona alkaloid-derived phase-transfercatalysts bearing multiple hydrogen-bonding donors (the first metal-free catalytic systems used in this reaction) was developed. A series of 3-substituted 3-amino-oxindoles were constructed using this protocol in excellent yields
L-tert-Leucine derived urea-ammonium salts: Efficient bifunctional phase transfer catalysts for highly diastereo- and enantioselective aza-Henry reaction of isatin-derived N-Boc ketimines with α-aryl nitromethanes
efficient way of aza-Henry reaction between isatin-derived N-Boc ketimines and α-aryl nitromethanes catalyzed by bifunctional phase transfer catalysts with a quaternary ammonium center derived from L-tert-Leucine has been developed. A series of 3-substituted 3-amino-oxindoles were constructed by this catalytic protocol in excellent yields (90–99%), with high enantioselectivities (83–95%) and diastereoselectivities