been synthesized. They are isomerized by short acid treatment to give a mixture of the four anomer/ring size combinations without any Wessely-Moser isomerization. In the same conditions molludistin (8-C-α- l -arabinopyranosylgenkwanin) led only to a mixture of molludistin and 8-C-α- l -arabinofuranosylgenkwanin. This is the first demonstration of ring sugar isomerization in C-glycosylflavones. In usual
摘要 6-C-α-1-Arabinopyranosyl-和furanosylacacetins 已被合成。它们通过短酸处理异构化,得到四种异头物/环尺寸组合的混合物,没有任何 Wessely-Moser 异构化。在相同的条件下,软体菌素(8-C-α-l-阿拉伯
呋喃糖素)仅产生软体菌素和 8-C-α-l-阿拉伯
呋喃素素的混合物。这是 C-糖基
黄酮中环糖异构化的首次演示。在通常的溶剂体系中,α-端基异构体很容易与 β-端基异构体分离,而相应的
吡喃糖基和
呋喃糖基端基异构体则不然。然而,它们在全甲基化后很容易分离,并且在 PM 6-C-阿拉伯
呋喃糖基异构体的质谱图中发现了特征。