Trans-Stereoselectivity in the Reaction between Homophthalic Anhydride and Imines

The reaction between homophthalic anhydride and imines in the presence of Ticl(4) and diisopropyl ethyl amine is trans-selective. Under these conditions, the reaction using homochiral imines can be highly diastereoselective, thus allowing the synthesis of enantiopure 1,2,3,4-tetrahydro-1-oxoquinoline-4-carboxylic acids.