A Synthesis of Pyrrolophenanthridone Alkaloids via Consecutive Directed Lithiation and Palladium-catalyzed Cross-coupling Reactions
摘要:
A short and convergent synthesis of pyrrolophenanthridone alkaloids, such as anhydrolycorin-7-one, oxoassoanine, hippadine, and pratosine, was developed by using directed lithiation and palladium-catalyzed cross-coupling as key reactions. Anhydrolycorin-7-one was converted to an antitumor alkaloid, kalbretorine, via directed lithiation and hydroxylation reactions.
An Oxazoline-Mediated Synthesis of the Pyrrolophenanthridine Alkaloids and Some Novel Derivatives
摘要:
An unsymmetrical biaryl coupling between the Grignard of N-benzyl-7-bromoindoline 25 and the appropriately substituted (o-methoxyaryl)oxazoline 15 leads to an intermediate biaryl which can be elaborated in one step to the 1H-pyrrolo[3,2,1-de]phenanthridine ring system. This simple two-step sequence provides general access to the pyrrolophenanthridine alkaloids 2-6.