Mayr Stefanie, Marin-Luna Marta, Zipse Hendrik
Department of Chemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377 München, Germany.
J Org Chem. 2021 Feb 19;86(4):3456-3489. doi: 10.1021/acs.joc.0c02848. Epub 2021 Feb 8.
Relative rates for the Lewis base-mediated acylation of secondary and primary alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydride derivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate size leads to an actual acceleration of the acylation process, the effect being larger for secondary as compared to primary alcohols. Computational results indicate that acylation rates are guided by noncovalent interactions (NCIs) between the catalyst ring system and the DED substituents in the alcohol and anhydride reactants. Thereby stronger NCIs are formed for secondary alcohols than for primary alcohols.
已测定了带有大的芳族侧链的仲醇和伯醇在Lewis碱介导下与大小和电子结构不同的酸酐进行酰化反应的相对速率。在用单取代苯甲酸酐衍生物进行的转化中，伯醇的反应速度比仲醇快，而在与空间位阻较大的1-萘甲酸酐的反应中，相对反应活性则相反。对反应速率的进一步分析表明，底物尺寸的增加会导致酰化过程实际加速，仲醇的这种效应比伯醇更大。计算结果表明，酰化速率受催化剂环系统与醇和酸酐反应物中的DED取代基之间的非共价相互作用（NCI）的引导。因此，仲醇形成的NCI比伯醇更强。
