Benzoylation of N-acetylneuraminic acid (Neu5Ac) gave a variety of partially benzoylated bicyclic 1, 7-lactone derivatives and a perbenzoylated bicyclic 1, 4-lactone derivative in good yields. The structures of these compounds were elucidated mainly by means of proton nuclear magnetic resonance spectroscopy.Further, pivaloylation and ethoxycarbonylation of Neu5Ac also gave the corresponding acylated bicyclic lactone derivatives.These results allowed us to postulate a mechanism for the formation of bicyclic lactone derivatives in the acylation of Neu5Ac. Furthermore, treatment of Neu5Ac with diazomethane in an acidic methanol solution gave methyl a-D-neuraminoside methyl ester and a monocyclic 2-O-methyl-y-lactone derivative in 18% and 29% yields, respectively.These results provided information about the equilibrium of Neu5Ac in basic and acidic media.
N-acetyl neuraminic acid(Neu5Ac)
苯甲酰化反应产生了多种部分
苯甲酰化的双环 1,7-内
酯衍
生物和一种全
苯甲酰化的双环 1,4-内
酯衍
生物,产率良好。此外,Neu5Ac 的新戊酰化和乙
氧基羰基化也得到了相应的酰化双环内
酯衍
生物。这些结果使我们能够推测 Neu5Ac酰化过程中双环内
酯衍
生物的形成机制。此外,在酸性
甲醇溶液中用
重氮甲烷处理 Neu5Ac,可得到
甲基 a-D-神经
氨酸甲
酯和单环 2-O-
甲基内酯衍
生物,收率分别为 18% 和 29%。