关键词: 不对称催化, 立体化学, 立体选择性, 核磁共振谱图

Abstract: The proline-catalyzed asymmetric aldol reaction stands as a classic experiment illustrating the concept of enantiomerism. However, due to substrate reactivity limitations and experimental constraints, the stereochemical concepts of diastereoisomerism and racemization have not been adequately addressed. To bridge this gap between experimental and theoretical teaching and enhance students’ understanding of stereochemistry in Organic Chemistry, we have innovated and expanded the proline-catalyzed asymmetric aldol reaction. Firstly, by upgrading the conventional two-component reaction to a three-component reaction, we efficiently generate diastereomers through the conversion of arylaldehydes to highly reactive aldimines. Secondly, we introduce the stereoselective control of proline through the use of catalysts with opposite chiral configurations, while also incorporating the concept of racemization by mixing products with opposite configurations. Thirdly, we employ nuclear magnetic resonance (NMR) technology to elucidate the diastereoisomerism ratio of the products, facilitating a deeper understanding of diastereoisomerism concepts. Our results demonstrate that this experiment offers excellent repeatability, appropriate duration, and a balance of exploration and innovation. Implementation of this project not only enhances students’ scientific inquiry and innovative thinking but also cultivates their ability to conduct innovative experiments.

Key words: Asymmetric catalysis, Stereochemistry, Stereoselectivity, NMR spectroscopy