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Asymmetric [4+2] Annulation of C1 Ammonium Enolates with Copper-Allenylidenes
Jin Song1, Zi-Jing Zhang1, Liu-Zhu Gong1,2
1Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
Angewandte Chemie (International Ed. in English)
|April 4, 2017
Abstract:
An asymmetric catalytic decarboxylative [4+2] annulation of 4-ethynyl dihydrobenzooxazinones and carboxylic acids has been established by cooperative copper and nucleophilic Lewis base catalysis. A C1 ammonium enolate and copper-allenylidene complex, each catalytically generated from different substrates, underwent a cascade asymmetric propargylation and lactamization process to yield optically active 3,4-dihydroquinolin-2-one derivatives with excellent levels of stereoselectivity (up to 99 % ee, 95:5 d.r.).