Oxidative γ-Addition of Enals to Trifluoromethyl Ketones: Enantioselectivity Control via Lewis Acid/N-Heterocyclic Carbene Cooperative Catalysis
作者:Junming Mo、Xingkuan Chen、Yonggui Robin Chi
DOI:10.1021/ja303618z
日期:2012.5.30
An oxidative γ-functionalization of enals under N-heterocyclic carbene (NHC) catalysis to give unsaturated δ-lactones is disclosed. Enantioselectivity control involving the relatively remote enal γ-carbon was achieved via Lewis acid [Sc(OTf)(3) or combined Sc(OTf)(3)/Mg(OTf)(2)] and NHC cooperativecatalysis.
Green and Rapid Access to Benzocoumarins<i>via</i>Direct Benzene Construction through Base-Mediated Formal [4+2] Reaction and Air Oxidation
作者:Chengli Mou、Tingshun Zhu、Pengcheng Zheng、Song Yang、Bao-An Song、Yonggui Robin Chi
DOI:10.1002/adsc.201500771
日期:2016.3.3
typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal‐catalyzed coupling or carbon‐hydrogen bond activation reactions starting with pre‐existing aryl frameworks in the substrates. Here we report a new strategy for the green and rapidaccess to benzocoumarins and their derivatives. Our method uses readily available
Carbene-Catalyzed Formal [3+3] Cycloaddition Reaction for Access to Substituted 2-Phenylbenzothiazoles
作者:Zhibin Ni、Chengli Mou、Xun Zhu、Puying Qi、Song Yang、Yonggui Robin Chi、Zhichao Jin
DOI:10.1002/ejoc.201901773
日期:2020.1.31
carbene‐catalyzed oxidative cycloadditionreaction is developed for efficient access to multi‐functionalized 2‐phenylbenzothiazoles. A broad scope of heavily substituted arenes bearing 2‐benzothiazole groups have been prepared in good to excellent yields. The remote C(sp2)–H bond in the substituted arene products can be regioselectively activated by Pd catalysts with the direction of the 2‐benzothiazole groups
Carbene-Catalyzed Formal [5 + 5] Reaction for Coumarin Construction and Total Synthesis of Defucogilvocarcins
作者:Xuan Huang、Tingshun Zhu、Zhijian Huang、Yuexia Zhang、Zhichao Jin、Giuseppe Zanoni、Yonggui Robin Chi
DOI:10.1021/acs.orglett.7b03102
日期:2017.11.17
An N-heterocyclic carbene-catalyzed formal [5 + 5] reaction between enals and furanones that generates multisubstituted coumarins in a single step is reported. Five atoms in each of the substrates are involved in this catalytic process to form a benzene and a lactone ring. The power of the method is further demonstrated in metal-free total syntheses of several natural products (defucogilvocarcins M
N‐Heterocyclic Carbene Catalyzed Synthesis of Dihydroxybenzophenones from β‐Methylenals and Aurones
作者:Kun‐Quan Chen、Zhi Luo、Zhong‐Hua Gao、Song Ye
DOI:10.1002/chem.201806225
日期:——
N‐heterocyclic carbene catalyzed synthesis of 2,2′‐dihydroxybenzophenones from β‐methylenals and aurones was developed. The cleavage of the C−O bond by a retro‐Michael addition is the key step from the spirocyclic intermediate to final product.