Hamigeromycins C–G, 14-membered macrolides from the fungus Hamigera avellanea BCC 17816
摘要:
Five new 14-membered macrolides, hamigeromycins C-G, together with the previously described compounds, hamigeromycin A and 89-250904-F1 (radicicol analog A), were isolated from the fungus Hamigera avellanea BCC 17816. Hamigeromycins A, C, D, and E are stereoisomers differing from one another in the absolute configurations of the 4',5'-diol moiety. Hamigeromycins F and G are unusual 5'-keto-analogs, and they are 6'-epimers to each other. The structures and the stereochemistry of the new compounds were deduced by analyses of the NMR spectroscopic and mass spectrometry data in combination with chemical means. (C) 2009 Elsevier Ltd. All rights reserved.
首次实现了两种天然存在的间苯二酚酸内酯(RAL)——哈米庆霉素 F 和 G 的不对称全合成。合成策略涉及通过酯交换反应实现的后期分子内大内酯化。通过酶动力学拆分反应获得两个分子中的立构中心(C 10'和 C 6' )。使用香草醛作为前体获得存在于哈米庆霉素 F 和 G 中的五取代芳香核。 C 1′ –C 2′处关键的E-烯属不饱和键是通过立体选择性 Julia-Kocienski 烯化反应构建的。