Diastereoselective Synthesis and Characterization of Homoallylic <i>N</i>-<i>tert</i>-Butanesulfinyl Amines: An Asymmetric Synthesis Experiment for the Undergraduate Organic Laboratory

Abstract

An asymmetric synthetic experiment that encompasses the knowledge of stereoselectivity and the practice of Schlenk techniques is described. In this experiment, Zn-mediated allylation of an (R)-N-tert-butanesulfinyl imine is performed using different conditions of solvent and additive. The reactions give both diastereomers in good yields and in various diastereomeric ratio (dr), which is determined by 1 H, 19 F NMR spectroscopy and chiral HPLC. Overall, this experiment can be carried out with readily accessible reagents under mild conditions, and be finished within limited laboratory time. Moreover, it enables students to learn the basics of Schlenk techniques, the differences between enantiomers and diastereomers, how a reversal of stereochemical outcome is realized by tuning the reaction solvent and additive, and the determination of dr regarding optical compounds using HPLC and NMR spectroscopy.