Imine is formed with stereoselectivity through S-ARCA solution and aqueous solution of DL-amino acids with a phase transfer catalyst at the basic condition. After imine formation, excess DL-amino acids in the aqueous solution are reused as they are, or they are reused after additional racemization. After the hydrolysis of the imine, D-amino acids are obtained. R-ARCA can also be used to obtain L-amino acids through the same process. This reactive extraction process in which ARCA is used as a reusable extractant is called "shuttle process."