Optimizing the Structure of 4-Dialkylamino-α,α-diarylprolinol Ethers as Catalysts for the Enantioselective Cyclopropanation of α,β-Unsaturated Aldehydes in Water
作者:Jose I. Martínez、Efraim Reyes、Uxue Uria、Luisa Carrillo、Jose L. Vicario
DOI:10.1002/cctc.201300097
日期:2013.8
water as the reaction solvent. Moreover, the reaction was studied by computational methods, which indicated that the overall transformation proceeded through a cascade Michael/α‐alkylation sequence, in which the first iminium‐mediated Michael addition reaction was the rate‐determining step and also the step at which stereochemical information was transferred from the catalyst to the products.
我们优化了新的手性二芳基脯氨醇型有机催化剂家族的结构,改善了在水中进行的共轭加成反应中的性能,并在亚胺基活化歧管下进行。催化剂设计的原理是,首先,在吡咯烷支架的4位上引入叔氨基,这可以通过提供有利于亲核试剂去质子化的碱性位点来促进反应,其次,体积大。二芳基三烷基甲硅烷基氧基甲基保持在2位上以控制亚胺离子的几何形状并提供面部立体选择所需的空间偏倚。该4-二烷基氨基的性质以及相对的2,优化了4-构型,并证明了所得到的催化剂在使用水作为反应溶剂的α,β-不饱和醛催化对映选择性环丙烷化中的效率。此外,通过计算方法对反应进行了研究,结果表明整个转化过程是通过级联的迈克尔/α-烷基化序列进行的,其中第一个亚胺基介导的迈克尔加成反应是速率确定步骤,也是立体化学步骤。信息已从催化剂转移到产品中。