46 インターロイキン-1産生遊離阻害活性を有するキノイド型ジテルペンの開発(口頭発表の部)

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Triptoquinone A-C (1-3) are novel quinoid-type diterpenes recently isolated from the extracts of the Tripterygium wilfordii var. regelii and possess potent inhibitory activity against interleukin-1α and -1β releases from lipopolysaccharide-stimulated human peripheral mononuclear cells. In this paper, we report our synthetic efforts in this area. 1. Total Synthesis of (±)-Triptoquinone A Starting from 2-isopropyl-6-methoxy-1-naphthol, tricyclic enol triflate 17 was efficiently synthesized via a nine-step sequence. The total synthesis of triptoquinone A (1) was accomplished from 17 by palladium catalyzed carboxylation followed by oxidation with ceric ammonium nitrate (CAN). 2. Total Synthesis of (±)-Triptoquinone B and C Mn(OAc)_3 mediated oxidative cyclization of the olefinic keto ester 31 provided stereoselectively the tricycle 32, which was converted into triptoquinone C (3) by sequential LiAlH_4 reduction and oxidation with CAN. Chemoselective oxidation of the secondary alcohol moiety in 3 with aqueous NaOCl in AcOH completed the total synthesis of triptoquinone B (2). 3. Asymmetric Synthesis of Triptoquinone A and Determination of the Absolute Configuration of Triptoquinone B Chiral tricyclic enone S-11 was assembled in 91% ee via the Vandewalle asymmetric Robinson annulation using a chiral phase transfer catalyst. S-11 was then converted into (+)-triptoquinone A (1) via the same sequence as has been developed for the synthesis of the racemate. Additionally, for the determination of the absolute configuration of triptoquinone B (2), S-11 was transformed into the tricyclic ketone 38. The optical rotation of 38 thus obtained was completely identical with that of 38, which was alternatively derived from natural 2.
天然有機化合物討論会の論文
1992-09-10

46 インターロイキン-1産生遊離阻害活性を有するキノイド型ジテルペンの開発(口頭発表の部)

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