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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.).
Song et al. (Fri,) studied this question.