Asymmetric aldol reaction catalyzed by amino acid tetrapeptides (l-Pro-l-Pro-l-Phe-l-Phe-OMe)

Abstract

Metal-free catalysts have become one of the important research directions in catalysis due to increasing heavy metal pollution. In this paper, the synthesized aromatic amino acid dipeptide (L-Phe-L-Phe-OMe) was connected with a proline dipeptide (L-Pro-L-Pro) by solid phase synthesis reaction to produce the heterogeneous catalyst L-Pro-L-Pro-L-Phe-L-Phe-OMe. The structure of this catalyst was characterized by means of SEM, XRD, and NMR and FTIR spectroscopy. X-ray diffractometry revealed that L-Pro-L-Pro-L-Phe-L-Phe-OMe has a rod crystal structure. Moreover, L-Pro-L-Pro-L-Phe-L-Phe-OMe showed better catalytic activity than a homogeneous small molecule catalyst (high enantioselectivity, ee > 97%) in heterogeneous asymmetric aldol reactions and had good recyclability.