对映-贝壳杉烯二萜分子内氢键对6,7位羟基化学反应性影响研究

The Effect of Intramolecular Hydrogen Bond on Reactivity of 6,7- Hydroxyl Groups to Acetylation in ent - Kaurene Diterpenoids

对映-贝壳杉烯二萜分子在激烈条件下进行乙酰化反应,反应发生在半缩醛羟基,而非仲羟基上;该反常现象的产生可能是由于6位仲羟基与15位羰基之间形成了分子内氢键,本文根据~1H NMR变温实验观察分子在不同温度时6位和7位羟基质子的化学位移变化值△δ/T(H_z·K^(-1)),证明了上述假定。

Ent - kaurene diterpenoids were acetylated under a strong reaction condition to afford 7 - acetyl products without 6 or 6' - acetyl ones. This uncommon phenomenon may be due to the presence of hydrogen bond(s) between 6 - hydroxyl and 15 - ketone carbonyl. This hypothesis was unambiguously confirmed by the temperature gradients values Δδ/T (Hz· K-1) of 6, 6' 7 and 7' -hydroxyl group signal.