84(P11) イチイから分離した微生物Pestalotiopsis sp.の生産する新規セスキテルペンの構造決定(ポスター発表の部)

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Five new sesquiterepenes have been isolated from Pestalotiopsis sp., an endophytic fungus associated with the bark and leaves of Taxus brevifolia. Pestalotiopsins A(1), B(2), and C(3) were novel caryophyllene sesquiterepenes with highly oxygenated functional groups. Pestalotiopsin B exists as two slowly equilibrating atropisomers of 14β, 15α confomer (2a) and 14β, 15β conformer (2b) in the ratio of 6: 5. Structures of (1)-(3) were determined by detailed NMR studies including PFG-DQFCOSY, PFG-HMQC, PFG-HMBC and NOE differencial spectroscopy or selective PFG-ROESY experiments, and in the case of (1) and (2) single crystal X-ray diffraction analysis. Crystal structure of (2) was minor conformer of (2b). Two other sesquiterpenes were drimane type 2α-hydroxyisodrimeninol (4) and humulane type 3-hydroxymethyl-7,11,11-trimethyl-(2Z, 6E)-cycloundecadien-5,10-dione (5). Two acetogenins, (2E, 4S^*, 5R^*, 6Z, 8E)-4,5-dihydroxy-6-hydroxymethyl-2,6,8-decatriene (6) and (4S^*, 5R^*, 6Z, 8E)-4,5-dihydroxy-6-hydroxymethyl-6,8-decadiene (7) were also isolated from the fungus. To establish the absolute configuration of pestalotiopsin B (2), the Sharpless reaction with both diethyl tartarates were performed yielding the monoepoxides (13) and (14) in a different ratio. The structure of the epoxides were determined by NMR analysis and comparison of related compounds (8)-(12) prepared by MCPBA reaction. The 7,8-β-epoxide (13) also exists as two confomers (13a) and (13b) as (2), but the 7,8-α-epoxide (14) exists as one confomer of 14α, 15α form. Based on the results of the Sharpless reaction and the structures of the monoepoxides (13) and (14), the absolute structure of pestalotiopsin B (2) was determined to be (1S, 2S, 4E, 6R, 7E, 9R)-2-acetoxy-6-methoxy-4,7-caryophylladiene.
天然有機化合物討論会の論文
1997-07-20

84(P11) イチイから分離した微生物Pestalotiopsis sp.の生産する新規セスキテルペンの構造決定(ポスター発表の部)

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