Intramolecular Copper-Catalyzed Asymmetric Propargylic [4 + 2]- Cycloaddition toward Optically Active Tetrahydroisoindolo[2,1-]quinoxalines.

An intramolecular Cu-catalyzed asymmetric propargylic [4 + 2] cycloaddition of bis--nucleophile-functionalized propargylic esters has been realized in the support of a chiral tridentate N-ligand, (,)-Pybox-diOAc, leading to chiral tetrahydroisoindolo[2,1-]quinoxalines in high yields and with good to excellent enantioselectivities. The reaction features high efficiency, simplicity, and broad substrate scope, thus providing a powerful and concise strategy for stereoselective access to optically active polycyclic heterocycle frameworks that are otherwise difficult to synthesize.