40 フッキソウアルカロイドの相互変換 : Pachystermine-A及び-Bの合成

概要

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Pachystermine-A (I) and -B (II), isolated from Pachysandra terminalis SIEB. et ZUCC., are unique in that they carry a β-lactam ring system in the molecule. These alkaloids are now synthesized from epipachysandrine-A (III), a minor alkaloid obtained from the same plant. At first we examined the conversion of pachystermine-diol (IV) to I and II. IV was transformed to the mono-O-acetate (VII) which was then oxidized to the amino acid (VIII). β-Lactam cyclization of this amino acid was successfully performed by the action of DCCD in CH_2Cl_2 to give IX. Subsequent treatment of the latter (IX) with LiAlH_4 under controlled condition afforded pachystermine-B (II), which can be oxidized to pachystermine-A (I) as reported already. Conversion of epipachysandrine-A (III) to a mixture of 3'-epimeric diols (XIII) was easily achieved in essentially reported manner. However, attempts to separate pachysterminediol (IV) from this mixture were unsatisfactory. Eventually N-methylpachystermine-diol (XVA), which could readily be isolated from the 3'-epimeric mixture, was converted to pachystermine-diol (IV) as shown in Chart 2.
天然有機化合物討論会の論文
1967-09-25