Department of Chemistry, LMU München, Butenandtstr. 5-13, 81366, München, Germany.
Chemistry. 2021 Dec 23;27(72):18084-18092. doi: 10.1002/chem.202101905. Epub 2021 Nov 29.
Relative rates for the Lewis base-catalyzed acylation of aryl-substituted 1,2-diols with anhydrides differing in size have been determined by turnover-limited competition experiments and absolute kinetics measurements. Depending on the structure of the anhydride reagent, the secondary hydroxyl group of the 1,2-diol reacts faster than the primary one. This preference towards the secondary hydroxyl group is boosted in the second acylation step from the monoesters to the diester through size and additional steric effects. In absolute terms the first acylation step is found to be up to 35 times faster than the second one for the primary alcohols due to neighboring group effects.
相对速率的lewis 碱催化酰化取代芳烃 1,2-二醇与酸酐不同大小已经确定通过周转限制竞争实验和绝对动力学测量。根据酸酐试剂的结构，1,2-二醇的仲羟基比伯羟基反应更快。这种对仲羟基的偏爱在通过大小和额外的空间位阻效应从单酯到二酯的第二步酰化反应中得到增强。从邻基效应来看，对于伯醇来说，第一个酰化步骤的速度比第二个酰化步骤快 35 倍。
