高等学校化学学报Issue(11)：2262-2270,9.DOI:10.7503/cjcu20150649
铂催化2-烯炔苯甲醛水合环化反应的机理及化学选择性的理论研究
Theoretical Studies on the Mechanism of Water-dependent Chemoselectivity in the Pt-Catalyzed Hydrative Cyclization of 2-Enynylbenzaldehydes
摘要
Abstract
With the aid of density functional theory( DFT) calculations, we made a detailed mechanism study on the origin of chemoselectivity in Pt-catalyzed hydrative cyclizations of 2-enynylbenzaldehydes. The calculations indicate that the formation of platinum-pyrylium intermediate is initiated by the activation of alkyne. Successive [ 3+2 ] cycloaddition with a double bond leads to the platinum-carbene complex. After that, the reaction proceeds along either pathway Ⅰ or pathway Ⅱ to yield products 3a and 4a, depending on the subsequent two-step water-assisted proton-transfer process. The calculated barrier leading to product 3a is 146. 5 kJ/mol. For the formation of product 4a, the tautomerization(from enol to keto form) is the rate-determining step with a barrier of 185. 8 kJ/mol when one water molecule is involved. However, when two and three water molecules are involved in catalysis, the barrier is reduced to 128. 1 and 64. 9 kJ/mol respectively. Therefore, the reaction preferentially proceeds along the pathwayⅡleading to product 4a. Water molecules that act as a cocatalyst in the tautomerization process are mainly responsible <br> for the good selectivity. This result rationalizes well the experimental observations and provides a new insight into the Pt-catalyzed hydrative cyclizations.关键词
铂催化/化学选择性/水合环化反应/反应机理/密度泛函理论Key words
PtCl2 catalysis/Chemoselectivity/Hydrative cyclization/Mechanism/Density functional thoery分类
化学化工引用本文复制引用
郭今心,朱荣秀,张冬菊,李明霞,刘成卜..铂催化2-烯炔苯甲醛水合环化反应的机理及化学选择性的理论研究[J].高等学校化学学报,2015,(11):2262-2270,9.基金项目
国家自然科学基金(批准号:21433006)和山东省自然科学基金(批准号：ZR2013BM026,2014ZRE27295)资助 （批准号:21433006）
