Catalytic Enantioselective Tautomerization of Metastable Enamines

The first example of catalytic enantioselective tautomerization of structurally labile but isolable enamines for accessing their chiral imine-tautomers is described. Kinetically stable enamine-based dibenzo­[b,d]­azepines were tautomerized by a simple chiral BINOL–phosphoric acid, providing a variety of seven-membered imine products bearing both central and axial stereogenic elements in good yields (up to 96%) with excellent enantio- and diastereoselectivities (up to 97% ee, >20:1 dr).