A comparative study of the O-3 reactivity of isomeric N-dimethylmaleoyl-protected d-glucosamine and d-allosamine acceptors
作者:María I. Colombo、Carlos A. Stortz、Edmundo A. Rúveda
DOI:10.1016/j.carres.2011.01.017
日期:2011.4
Four isomeric N-dimethylmaleoyl 4,6-O-benzylidene-protected d-hexosamine acceptors (2, 3, 4, and 5) with all possible configurations at C-1 and C-3 (e.g., derived from d-glucosamine and D-allosamine) were prepared, and the assessment of their O-3 relative reactivity through competition experiments using the known per-O-acetylated D-galactopyranosyl trichloroacetimidate donor (15) was then carried out
四个同分异构的N-二甲基马来酰基4,6-O-亚苄基保护的d-己糖胺受体(2、3、4和5),在C-1和C-3处具有所有可能的构型(例如,衍生自d-葡萄糖胺和D -allosamine),然后使用已知的过-O-乙酰化D-吡喃半乳糖基三氯乙酰亚氨酸酯供体(15)通过竞争实验评估其O-3相对反应性。反应性顺序为4 >> 2> 5> 3。2-5在不同温度下的NMR光谱分析以及对2-5类似物(DFT)和受体本身(MM)进行的建模实验是一致的,并且有助于建立不同氢键的稳定性,以及随身携带的构形器。整个结果表明,尽管最具反应性的羟基呈轴向构象,但仍需要电子效应(氢键)来解释观察到的趋势。仅当氢键较弱时才会出现空间效应。