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 Et
4NOTs 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.
抄録全体を表示