Sedum alkaloids. XI. Synthesis of sedinone and sedacrine by application of anodic oxidation

Abstract

α-Methoxycarbamate 12, synthetic precursor of the 2,6-disubstituted alkaloids of Sedum acre, was obtained in high yield from 2-phenacylpiperidine 5; the key step of the synthesis rests on the anodic methoxylation, which allows the functionalization of carbon 6. Nucleophilic substitution of the methoxy group by an acetonyl chain leads, after the required transformations, to sedinone 23. Bromomethoxylation of the enecarbamate 19 followed by dehydrohalogenation and nucleophilic substitution of the methoxy group leads to sedacrine 33. In both cases, the nucleophilic substitution of the methoxy group leads to a cis 2,6-disubstituted piperidine derivative. Key words: synthesis, piperidine alkaloids, anodic methoxylation