65 糖質synthonを用いる生理活性天然物の合成

概要

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In order to obtain the chiral part of the antibiotic A23187 (1) which is a divalent cation ionophore crystallized from cultures of Streptomyces chartreusensis, an attempt to use the chiral synthons (5) and (6) prepared from D-glucose was explored. D-Glucose was converted to the compound (7) via 7 steps in the reported manner. The chiral centers of (7) should provide the stereochemistry necessary to both of the synthons (5) and (6). Preparation of synthon (5) Hydride reduction of (7) followed by acetolysis gave triacetate (10), which, after saponification, was treated sequentially with・NaIO_4 and NaBH_4 to afford triol (12). Corresponding acetonide derivative (13) was converted to the iodide (15) via tosylate (14). Preparation of synthon (6) Exo-methylene compound (16) obtained by Wittig reaction of (7) was hydrogenated to give axial methyl compound (17) in preference to its isomers (18). (17) was converted to the amide (33) in 4 steps and it was heated with cupric sulfate hydrate in toluen to afford the bicyclic compound (36). An additional methyl group with the desired configuration was introduced by alkylation of the imino ether (39) with LDA-CH_3I. Cleavage of the imino ether (40) and reduction with LAH gave (42) which was further transformed to the dithioacetal (45) having the hydroxyl groups protected.
天然有機化合物討論会の論文
1979-09-20