23 (+)-パスパリシン及び(+)-パスパリニンの全合成(ポスター発表の部)

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概要

• 論文の詳細を見る

• The first total syntheses of (+)-paspalicine (2) and (+)-paspalinine (3) have been achieved, respectively, exploiting a unified strategy which earlier afforded (-)-paspaline. In constrast with the paspaline venture, wherein the indole nucleus was incorporated late in the synthesis, our point of departure for paspalicin and paspalinine entailed the conversion of common intermediate (10) to (13) via the Gassman indole protocol. With the ABCDE-ring system of the simple tremogens, we envisioned installation of ring F and G via alkylation of the thermodynamic enolate derived from (13) with epoxide (20). Coupling of enone (13) and epoxide (20) proceeded the Stork metalloenamine protocol (i.e, conversion of (13) to the corresponding dimethylhydrazone, deprotonation [LDA(1.9 equiv), THF, 65℃, 15h], and alkylation with (20). Best results required rigorous exclusion of oxygen. Workup with benzoic acid to provide (35). Acetylation of secondary hydroxyl, hydrazone hydrolysis, acid-promoted deketalization with concomitant cyclization, and acetal removal then afforded (39). Moffat oxidation provided β,γ-unsaturated enone (40), along with a minor amount of (+)-paspalicine (2) (ca. 4:1). Grieco's rhodium chloride protocol effected complete conversion from (40) to (+)-paspalicine (2). Furthermore, oxidation of (+)-2 with selenium dioxide then provided (+)-paspalinine (3). Synthetic (+)-2 and (+)-3 were identical in all respects with authentic samples.

• 天然有機化合物討論会の論文
• 1991-09-07

著者

• 砂塚 敏明

  北里研究所・生物機能研究所

• Smith A.

  ペンシルバニア大

• Leenay T.

  ペンシルバニア大

• Wood J.

  ペンシルバニア大

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