38 石こくアルカロイドの合成研究

概要

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The synthetic studies on Dendrobium alkaloids have been carried out by the route considering the biogenesis that the picrotoxane skeletone is derived from cadinane (A). The synthesis of dendrobine (1), the principal alkaloid of Dendrobium nobile L. was completed. Starting from α-tetralone (2), the two diastereoisomers (10a) and (10b) of the properly functionalized cis-hydrindane were prepared. The keto acid (10a) was converted to the keto lactam (22) via intermediates (20) and (21). The isopropyl group was introduced in this stage by the sequence; (22)→(23)→(24)→(25)→(26). The epimerization of (26) followed by reduction of the keto group to the hydroxyl afforded (±)-oxodendrobine (28), which was then led to (±)-dendrobine (1) by reduction of the pyrrolidone part to the corresponding amine. As a crucial step for the synthesis of 2-hydroxydendrobine (29) and dendroxine (30), hydroxylation at C-2 of the tricyclic compound (22') was examined affording the desired product (31) in moderate yield.
天然有機化合物討論会の論文
1972-10-01