title: Asymmetric [4+2] Annulation of C1 Ammonium Enolates with Copper-Allenylidenes.
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.).
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Song
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Zi-Jing
authors.initials: ZJ
authors.lastname: Zhang
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China.
authors.forename: Liu-Zhu
authors.initials: LZ
authors.lastname: Gong
keywords: C1 ammonium enolates; [4+2] annulations; cooperative catalysis; copper; heterocycles