電極酸化を鍵反応とするピペリジンアルカロイドおよびその前駆体の新規合成法

抄録

This article describes new methods to introduce a variety of substituents into the α, β or γ position of a piperidine ring by utilizing anodic oxidation as a key reaction. The following patterns of anodic oxidation were exploited to activate the α and, β positions of N-methoxycarbonylpiperidines A; (1) anodic oxidation of A in methanol containing Et₄NOTs to give the α-methoxylated products B, (2) anodic oxidation of A in acetic acid to give the a, /9-bisacetoxylated products C, (3) anodic oxidation of A to afford β-halogenated α-hydroxy-or α-methoxy-piperidine derivatives D, and (4) anodic decarboxylation of pipecolinic acid derivatives to afford B or C. The γ- position of A was activated by converting B or D into β, γ-unsaturated a-methoxypiperidine derivatives E. The activated compounds B, C, D and E were used as useful precursors to introduce substituents into the desired positions of piperidine ring, and some alkaloids containing a piperidine skeleton such as coniine, optically active N-methylconiine, conhydrine, and eburnamonine were synthesized from these precursors.