90 Urdamycinone Bの全合成(口頭発表の部)

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概要

• 論文の詳細を見る

• Urdamycins are a group of antibacterial and antitumor antibiotics which possess partially hydrogenated benz[a]anthracene nuclei, one C-glycosidic, and several O-glycosidic linkages. Urdamycinone B (2) was obtained by a controlled acid-treatment of urdamycin B (1), and also showed the antitumor activities. The first total synthesis of 2 is reported here. The present synthesis utilized polyketide condensation reactions for the construction of the aromatic rings. A polyketide 6 with a C-glycoside moiety on the side chain was generated from a glutarate 11 and acetoacetate dianion, and was aromatized to naphthalenediol 7 by the Ca(OAc)_2-promoted intramolecular condensation. The reactions were regio- and stereoselective, and the C-glycoside was introduced at 7-position of 7 with β-configuration. The selective conversion of the aliphatic carboxylate of 7 to methyl ketone was carried out by a Claisen condensation with lithiated 2-methyl-3-buten-2-yl acetate followed by a novel Pd-catalyzed decarboxylation. After the transformation of ketoester 13 to ketoaldehyde 14, the anthracene structure was constructed by an aldol reaction and K_2CO_3-induced intramolecular condensation. The use of the protected acetylacetone as the nucleophile was suggested from the model studies utilizing 15. Deprotection and oxidation converted anthracene 18 to anthraquinone 19. The final aldol reaction with NaOH at -25℃ gave 2 (enantiomer) and 3-epimer, which were separable by a reverse phase chromatography.

• 天然有機化合物討論会の論文
• 1990-09-25

著者

• 山口 雅彦

  九工大工

• 南 享

  九工大工

• 池浦 千夏

  九工大工

• 堀口 明

  九工大工

• 大熊 正

  九工大工

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