21 新規抗マイコプラズマ抗生物質Micacocidinの化学構造と全合成(口頭発表の部)

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Mycoplasmas cause infection of wide distribution throughout domestic animals, fowls, insects and plants, as well as human, and recently, the fact that mycoplasmas promote proliferation of HIV, is taken notice of people. Here we found new antimycoplasma antibiotic micacocidin (1) produced by Pseudomonas sp. Lot 57-250, and determined its chemical structure. Further, we challenged its total synthesis. Antimicrobial activity and chemical structure Micacocidin (1) shows high activity against mycoplasmas, especially Mycoplasma pneumoniae, which is causative bacteria of human pneumonia, selectively. (Table1) Micacocidin (1) is an octahedral chelated compound, contain one alkylsalicylic acid unit and three different thiazoline, thiazolidine skeletons, wherein the core is a bivalent zinc ion. (Figure 1.2) Synthesis of segment A Condensation of 10, derived from benzyl amine (7) via 6 step reactions, with protected cystein (11) gave amide (12). Treatment of 12 with phosphorus pentachloride gave thiazoline (13), though obtained achiral. After dealkylation, conversion of 13 to Weinreb amide (15) and subsequent reduction gave very unstable aldehyde (2). (Scheme 2) Synthesis of segment B After protection, N-Me-L-Cys (16) was converted to 18 by C-C bond formation reaction with CDI-method. Reduction of ketone (18) gave desired alcohol (19) stereoselectively. Configuration of 19 was substantiated by NOE examination of lactam (20) which was prepared from 19. (Scheme 3) Examination of total synthesis 19 was converted to 27 by protection of hydroxyl and hydrolysis. Condensation of 27 with 2-Me-R-CysOMe (22) gave amide (28). Cyclization and deprotection to give cysteamine (26), coupling of 26 and segment A (2) to give 29, hydrolysis and following chelation with zinc ion to complete total synthesis, are under way.(Scheme 5)
天然有機化合物討論会の論文
1996-09-02

21 新規抗マイコプラズマ抗生物質Micacocidinの化学構造と全合成(口頭発表の部)

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