Chemical Engineering Department, Facultad de Ciencias Químicas, Plaza de los Caídos 1-5, Salamanca E37004, Spain.
J Am Chem Soc. 2012 Oct 10;134(40):16869-76. doi: 10.1021/ja307712y. Epub 2012 Sep 28.
The mechanism of the reaction between di-tert-butyl azadicarboxylate and 1,3-dicarbonyl compounds catalyzed by an axially chiral guanidine is investigated by density functional theory methods. The results show that the catalyst acts simultaneously as a Brønsted base and an acid catalyst, and the mechanism is similar to that of the related BINOP organocatalysts. Surprisingly, cyclic and acyclic β-keto esters yield opposite enantiomers; the calculations demonstrate that this is a consequence of the preferred enolate geometry in the transition structures. Literature evidence suggests that other organocatalytic reactions show similar behavior.
通过密度泛函理论方法研究了手性胍催化下二特丁基偶氮二甲酸酯与 1,3-二羰基化合物的反应机理。结果表明，催化剂同时作为布朗斯特碱和酸催化剂，其机理与相关的 BINOP 有机催化剂相似。令人惊讶的是，环状和非环状β-酮酯生成相反的对映异构体；计算表明，这是过渡态中烯醇化物几何形状优先的结果。文献证据表明，其他有机催化反应也表现出类似的行为。
