32(D-2) プラジミシン-ベナノミシン系抗生物質の全合成(口頭発表の部)

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The pradimicin-benanomicin class antibiotics constitute a new class of natural products with a benzo[a]naphthacenequinone, amino acid and disaccharide moieties. They show anti-fungal and anti-HIV activities, which are related to the selective binding abilities to mannose-rich oligosaccharides, e.g., the mannane surface of fungi or gp 120 of HIV. The unique structure as well as the significant bioactivities les us to undertake the synthesis of this class of natural product. We have previously reported the stereoselective synthesis of the pradimicinone, the common aglycon of this class of natural products, by using the intramolecular pinacol coupling of the biaryl dialdehyde. A remaining problem is the regioselective introduction of the sugar to the pseudo-C_2 symmetric diol structure of the aglycon. Herein, we have completed total synthesis of pradimicin C. This synthesis features two key points; 1) Diastereoselective ring opening reaction of biaryl lactone 14 was conducted by employing optically active amino alcohol derived from D-valine as a nucleophile, gaving the axially chiral compound 15 in good yield with a high stereoselectivity, and 2) stereoselective semi-pinacol cyclization of acetal-aldehyde 18 by using Sml_2 with Lewis acid and water afforded the requisite tetracyclic 19, of which the vicinal diol moiety was suitably discriminated ready for introduction of disaccharide. Metallocene-promoted glycosylation of 20, derived from 19, effected to give glycoside 22, and further transformations involving the construction of E-ring skeleton and removal of all protecting groups led us to complete the total synthesis of 2.
天然有機化合物討論会の論文
2004-10-01

32(D-2) プラジミシン-ベナノミシン系抗生物質の全合成(口頭発表の部)

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