Studies on asymmetric synthesis of huperzine A. 1. Palladium-catalyzed asymmetric bicycloannulation of 5,6,7,8-tetrahydro-2-methoxy-6-oxo-5-quinolinecarboxylic esters

Article abstract of DOI:10.1016/S0040-4039(97)10535-4

A bridged bicyclic compound 8, the key intermediate for the synthesis of huperzine A (1), was prepared by asymmetric palladium-catalyzed bicycloannulation of β-keto ester 2. A variety of chiral ligands and reaction conditions were tested. 52% ee values were observed.