16 アシルニトロソ化合物のヘテロDiels-Alder反応を利用するホヤ由来抗腫瘍性3環性アルカロイドの合成(口頭発表の部)

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The first total syntheses of fasicularin (13) and lepadiformine (9), novel tricyclic marine alkaloids with cytotoxicity against tumor cell lines recently isolated from the marine ascidians Nephteis fasicularis and Clavelina lepadiformis respectively, have been achieved. The key strategic element was the intramolecular hetero Diels-Alder cycloaddition of N-acylnitroso compounds with exocyclic diene moieties, in which anti/syn-face selectivity was controlled. Thus, the B/C trans-fused cycloadduct 22 formed by the acylnitroso-Diels-Alder reaction proceeding with anti-facial selectivity was converted to (±)-fasicularin (13). On the other hand, the B/C cis-fused cycloadduct 35, obtained by the syn face selective acylnitroso-Diels-Alder reaction, was converted to "lepadiformine" having the originally proposed structure 9, which, however, was found to be clearly different from natural lepadiformine. The B/C trans-fused cycloadduct 22 was then converted to the new structrue 10 of lepadiformine identical in all respects with the natural product. These results indicate that the originally proposed structure 9 for lepadiformine is uncorrect and should be revised to the structure 10 we have synthesized in the present investigation.
天然有機化合物討論会の論文
1999-09-01