A synthesis of the core ABC ring system of the manzamine alkaloids is described, starting from arecoline. The key steps involve a Claisen rearrangement to set up a 4-substituted-3- methylenepiperidine and a stereoselective azomethine ylide dipolar cycloaddition reaction. Condensation of the aldehyde 6 and sarcosine ethyl ester hydrochloride salt gives an intermediate azomethine ylide, which undergoes an intramolecular cycloaddition reaction ...
