58 Naphthoquinone抗生物質の合成研究(±)-Frenolicin 及び(±)-Nanaomycin Aの全合成

概要

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The first stereoselective total syntheses of frenolicin and deoxyfrenolicin, and a new syntheses of nanaomycin A and kalafungin are described. 1) Synthesis of the key intermediate (10) The acetonide 8 derived from the Diels-Alder adduct 6 was reduced with LAH to give a diol 9. The oxidative cleavage of the diol 9, followed by epimerization of the aldehyde moiety gave the aldehyde 10. 2) Syntheses of (±)-nanaomycin A (2) and (±)-kalafungin (3) The key intermediate 10 was treated with CH_3MgI to give the hemiacetal 11, which was transformed into the alcohol 12. Oxidation of the alcohol 12 with chromium trioxide gave the ketone 13. The ketone 13 was treated with DDQ in the presence of p-TsOH to give 14. Epimerization of the quinone 14 gave (±)-nanaomycin A methyl ester, which was hydrolysed with KOH in methanol and water to give (±)-nanaomycin A. (±)-Nanaomycin A has already been transformed into (±)-kalafungin. 3) Syntheses of (±)-frenolicin (1) and (±)-deoxyfrenolicin (4) In a similar manner as above, (±)-deoxyfrenolicin was synthesized from the key intermediate 10. The stereoselective epoxidation of (±)-deoxyfrenolicin was accomplished with t-BuOOH and Triton B in the presence of VO(acac)_2.
天然有機化合物討論会の論文
1979-09-20