Functionalization of the Ring a in Some BenzogPyridazino1,2-bPhthalazine-6,13-Dione Derivatives Related to Anthracyclinones

摘要

A synthesis of benzogpyridazino 1,2-bphthalazine-6,13-dione derivatives (2) and (3),respectively related to the feudomicinone B and daunomicinone skeletons,has been accomplished by 4+2 cycloaddition of benzogphthalazine-l,4-dione with the adequate 1,3-diene.Functionalization of ring A with hydroxy substituents has been performed by reaction with N-bromosuccinimide in acid aqueous medium,sodium hydroxide,or hydrobromic acid via the corresponding epoxide,and the stereochemical features of electrophilic additions involved are commented in terms of steric and stereoelectronic factors.Easy isomerization of the C2-C3 double bond allows the introduction of hydroxy groups at the C1 or C4 positions,paving a way to further formation of the glycosides derivatives related to natural anthracyclines.