Xu, HaoZhang, HuJacobsen, Eric2014-09-162014Xu, Hao, Hu Zhang, and Eric N. Jacobsen. 2014. Chiral Sulfinamidourea and Strong Brønsted Acid–Cocatalyzed Enantioselective Povarov Reaction to Access Tetrahydroquinolines. Nature Protocols 9, no. 8: 1860–1866.1754-21891750-2799http://nrs.harvard.edu/urn-3:HUL.InstRepos:12872217This protocol describes a method for the laboratory synthesis of enantiomerically enriched, chiral tetrahydroisoquinolines through the application of a chiral sulfinamido urea catalyst for the Povarov reaction. Tetrahydroisoquinolines are bicyclic organic frameworks present in a wide assortment of natural and synthetic biologically important compounds including ​martinelline, ​scoulerine and ​tubocurarine. The methodology involves the [4+2] cycloaddition of a N-arylimines with electron-rich olefins such as vinyl lactams and dihydropyrroles in the presence of a two-catalyst system consisting of an achiral strong Brønsted acid (​o-nitrobenzenesulfonic acid), together with the chiral sulfinamido urea derivative 1. The anion-binding properties of the ​urea lead to the association of the ion pair that results from protonation of the imine substrate. Cycloaddition is followed by spontaneous proton loss with re-aromatization to provide the tetrahydroisoquinoline products in highly enantio-enriched form.en-USJournal Article2015-01-1210.1038/nprot.2014.125