Cyclomegistine, the first alkaloid with the new cyclobuta[b]quinoline ringsystem from Sarcomelicope megistophylla

A new quinolone, cyclomegistine, was isolated from the bark of Sarcomelicop e megistophylla. This alkaloid possesses the cyclobuta[b]quinoline ring sys tem that has not been previously described either from natural or from synt hetic origin. Biogenetically, cyclomegistine could arise from the oxidative aromatic ring cleavage of an acridone precursor, followed by photoisomeriz ation of the resulting butadiene into the isomeric cyclobutene. (C) 2001 El sevier Science Ltd. All rights reserved.