Bifunctional Tripeptide with a Phosphonic Acid as a Brønsted Acid for Michael Addition: Mechanistic Insights
作者:Margery Cortes-Clerget、Jesús Jover、Jade Dussart、Emilie Kolodziej、Maelle Monteil、Evelyne Migianu-Griffoni、Olivier Gager、Julia Deschamp、Marc Lecouvey
DOI:10.1002/chem.201700604
日期:2017.5.11
a widespread activation mode in the field of organocatalysis and is often encountered in bifunctional organocatalysts. We previously described H‐Pro‐Pro‐pAla‐OMe as a bifunctional catalyst for Michael addition between aldehydes and aromatic nitroalkenes. Considering that opposite selectivities were observed when compared to H‐Pro‐Pro‐Glu‐NH2, an analogue described by Wennemers, the activation mode of
烯胺催化是有机催化领域中广泛的活化方式,并且在双功能有机催化剂中经常遇到。我们之前将H-Pro-Pro-pAla-OMe描述为双官能催化剂,用于醛与芳族硝基烯之间的迈克尔加成。考虑到与Wennemers描述的类似物H-Pro-Pro-Glu-NH 2相比观察到相反的选择性,我们通过动力学,线性效应研究和NMR分析研究了H-Pro-Pro-pAla-OMe的激活方式,以及结构上的修改。似乎只有一种双功能催化剂参与了催化循环,方法是通过(E)-烯胺和硝基烯烃通过酸性相互作用。受约束的三肽结构在距离和刚度方面是最佳的,以实现更好的选择性和更快的反应速率。过渡态模型揭示了这种磷酸肽的特殊选择性。