Efficient Synthesis of (+)-Kalafungin and (-)-Nanaomycin D by Asymmetric Dihydroxylation, Oxa-Pictet-Spengler Cyclization, and H<sub>2</sub>SO<sub>4</sub>-Mediated Isomerization
作者:Reinhard Brückner、Rodney Fernandes
DOI:10.1055/s-2005-868505
日期:——
The pyranonaphthoquinone antibiotics and antitumor agents (+)-kalafungin (1) and (-)-nanaomycin D (3 = ent-1) were synthesized from 1,5-napthalenediol (13) in 11 steps. Stereocontrol was high: 99.5 ee/93% diastereoselectivity for 1, 98.5% ee/94% diastereoselectivity for 3. Enantiocontrol was achieved by the asymmetric dihydroxylation of the β,γ-unsaturated ester 9. Diastereocontrol was realized in the final step by an almost complete epimerization in H2SO4.
通过 11 个步骤从 1,5-萘二醇(13)合成了吡喃萘醌类抗生素和抗肿瘤药物 (+)-kalafungin (1) 和 (-)-nanaomycin D (3 = ent-1)。这两种化合物的立体选择性很高:1 的非对映选择性为 99.5%,3 的非对映选择性为 98.5%。δ,δ-不饱和酯 9 的不对称二羟基化实现了对映体控制。在最后一步,通过在 H2SO4 中几乎完全的外延化反应实现了非对映控制。