Enantioselective Alkylation of Glycine Imines Using a Cinchona-Functionalized Crown Ether-Strapped Calixarene Phase-Transfer Catalyst

J Org Chem. 2023 Jun 2;88(11):7498-7503. doi: 10.1021/acs.joc.3c00289. Epub 2023 May 22.

Abstract

We report a class of quaternary ammonium Cinchona-functionalized crown ether-strapped calix[4]arene phase-transfer catalysts for the efficient enantioselective α-alkylation of glycine imines. The catalyst exhibits excellent catalytic performance at 0.1 mol % catalytic loading, affording the desired α-alkylated glycinates with 98% yield and 99.9% ee. The catalyst could be recovered and recycled up to 30 test cycles without a significant drop in activity.