Regioselective Sulfonylation/Acylation of Carbohydrates Catalyzed by FeCl<sub>3</sub> Combined with Benzoyltrifluoroacetone and Its Mechanism Study
作者:Jian Lv、Jia-Jia Zhu、Yu Liu、Hai Dong
DOI:10.1021/acs.joc.9b03128
日期:2020.3.6
A catalytic amount of FeCl3 combined with benzoyl trifluoroacetone (Hbtfa) (FeCl3/Hbtfa = 1/2) was used to catalyze sulfonylation/acylation of diols and polyols using diisopropylethylamine (DIPEA) or potassium carbonate (K2CO3) as a base. The catalytic system exhibited high catalytic activity, leading to excellent isolated yields of sulfonylation/acylation products with high regioselectivities. Mechanism
使用二异丙基乙胺(DIPEA)或碳酸钾(K2CO3)作为碱,将催化量的FeCl3与苯甲酰基三氟丙酮(Hbtfa)(FeCl3 / Hbtfa = 1/2)结合用于催化二醇和多元醇的磺酰化/酰化。该催化体系表现出高催化活性,导致具有高区域选择性的磺酰化/酰化产物的优异分离产率。机理研究表明,FeCl3最初在碱性条件下于室温下于溶剂乙腈中以两倍的Hbtfa量形成[Fe(btfa)3](btfa =苯甲酰基三氟丙酮酸酯)。然后,在碱的存在下,Fe(btfa)3和底物的两个羟基形成五元或六元环中间体。环状中间体和磺酰化试剂之间的随后反应导致底物的选择性磺酰化。所有关键中间体均在高分辨率质谱分析中捕获,因此首次证明了这种机理。