エキヌリンおよび関連化合物の合成研究(第5報) : Aspergillus amstelodamiから得られるエキヌリン, ネオエキヌリン型天然物の抽出, 構造および合成

概要

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Six natural products, named E-6,E-7,E-8,E-9,E-10,and E-11,were isolated from ether and methylene chloride extracts of freeze-dried mycelium of Aspergillus amstelodami IFO-6667. E-9 and E-11 were found to be identical with neoechinulin (2) and echinulin (1), respectively, from spectroscopic and melting point data. Alkaline hydrolysis of E-7,E-8,and E-10 gave indole-3-carbaldehydes (4a, 4b and 4c), respectively. Analysis of the spectroscopic data revealed the presence of a methylenediketopiperazine moiety in E-7,E-8,and E-10. Based on these informations, the structures 3a, 3b, and 3c were assigned to E-7,E-8,and E-10,respectively. These three alkaloids were synthesized by condensation of indole-3-carbaldehydes (4a, 4b, and 4c) with methylenediketopiperazine (5). The stereochemistry of E-7,E-8,and E-10 were determined as shown in the structures. A possible rationalization to explain the isopentenylation in the echinulin-neoechinulin alkaloid biosyntheses was presented.
社団法人日本薬学会の論文
1977-05-25