Departamento de Química Orgánica I/, Kimika Organikoa I Saila, Facultad de Química/, Kimika Fakultatea Euskal Herriko Unibertsitatea, UPV/EHU and Donostia International Physics Center (DIPC), 1072, 20018 San Sebastián-Donostia (Spain).
Chemistry. 2013 Oct 4;19(41):13761-73. doi: 10.1002/chem.201301597. Epub 2013 Aug 21.
Density functional theory and Car-Parrinello molecular dynamics simulations have been carried out for model aldol reactions involving aggregates of lithium enolates derived from acetaldehyde and acetone. Formaldehyde and acetone have been used as electrophiles. It is found that the geometries of the enolate aggregates are in general determined by the most favorable arrangements of the point charges within the respective Lin On clusters. The reactivity of the enolates follows the sequence monomer≫dimer>tetramer. In lithium aggregates, the initially formed aldol adducts must rearrange to form more stable structures in which the enolate and alkoxide oxygen atoms are within the respective Lin On clusters. Positive cooperative effects, similar to allosteric effects found in several proteins, are found for the successive aldol reactions in aggregates. The corresponding transition structures show in general sofa geometries.
已针对涉及乙醛和丙酮衍生的锂烯醇化物聚集体的模型羟醛反应进行了密度泛函理论和 Car-Parrinello 分子动力学模拟。使用甲醛和丙酮作为亲电试剂。结果发现，烯醇化物聚集体的几何形状通常由各自 Lin On 簇内点电荷的最有利排列决定。烯醇化物的反应性遵循单体≫二聚体>四聚体的顺序。在锂聚合体中，最初形成的羟醛加合物必须重排，以形成更稳定的结构，其中烯醇化物和烷氧基氧原子在各自的 Lin On 簇内。在聚合体中，连续的羟醛反应表现出类似于在几种蛋白质中发现的变构效应的正协同效应。相应的过渡态结构通常呈现沙发式几何形状。
