Cincholenines A and B, two unprecedented quinoline alkaloids from Cinchona ledgeriana

Cincholenines A (1) and B (2), two novel quinoline alkaloids characterized with rearranged quinuclidine ring system, were isolated from the barks of Cinchona ledgeriana. The structures were elucidated on the basis of spectroscopic and quantum theory. A possible biogenesis was postulated.