In connection with studies directed towards the synthesis of the pyranonaphthoquinone antibiotic medermycin, C-aryl glycosides were prepared by C-glycosylation of naphthols with glycosyl donors. Boron trifluoride diethyl etherate proved to be a suitable Lewis acid to promote the C-glycosylation, and use of the azido glycosyl donor proved more successful than using the dimethylamino glycosyl donor. 5-Hydroxy-1,4-dimethoxynaphthalene underwent facile C-glycosylation with two particular glycosyl donors, whereas 3-bromo-5-hydroxy-1,4-dimethoxynaphthalene was not an effective coupling partner with the same glycosyl donors. These studies indicate that subtle steric and electronic effects need to be considered in order to fine-tune C-glycosylations when using highly functionalized glycosyl donors.
在合成
吡喃
萘醌类抗生素麦迪霉素的研究中,通过
萘酚与糖基供体的 C-糖基化反应制备了 C-芳基糖苷。事实证明,
三氟化硼二
乙基醚是促进 C-糖基化的合适
路易斯酸,使用
叠氮糖基供体比使用二
甲基氨基糖基供体更成功。5-羟基-
1,4-二甲氧基萘与两种特定的糖基供体进行了简便的 C-糖基化反应,而
3-溴-5-羟基-
1,4-二甲氧基萘与相同的糖基供体则不能进行有效的偶联。这些研究表明,在使用高度官能化的糖基供体时,需要考虑微妙的立体和电子效应,以便对 C-糖基化进行微调。