Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction

Yiwen Xiong; Haibo Mei; Lingmin Wu; Jianlin Han; Yi Pan; Guigen Li

doi:10.3762/bjoc.10.57

Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction

Beilstein J Org Chem. 2014 Mar 13:10:653-9. doi: 10.3762/bjoc.10.57. eCollection 2014.

Authors

Yiwen Xiong¹, Haibo Mei², Lingmin Wu¹, Jianlin Han³, Yi Pan¹, Guigen Li⁴

Affiliations

¹ School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China.
² School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China ; Institute for Chemistry & BioMedical Sciences, Nanjing University, Nanjing, 210093, China.
³ School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China ; Institute for Chemistry & BioMedical Sciences, Nanjing University, Nanjing, 210093, China ; High-Tech Research Institute of Nanjing University, Changzhou, 213164, China.
⁴ Institute for Chemistry & BioMedical Sciences, Nanjing University, Nanjing, 210093, China ; Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, 79409-1061, USA.

Abstract

A variety of chiral N-phosphinyl α-imino esters have been synthesized for the first time from ketoesters and phosphinylamide, which were then reduced by L-selectride to give the corresponding N-phosphinyl-protected α-amino esters. The reduction proceeded very well with excellent chemical yields (88-98%) as well as high diastereoselectivities (96:4 to 99:1). Some of these products could be obtained without column chromatography and recrystallization. The chiral phosphinyl auxiliary could be easily cleaved under acidic conditions.

Keywords: group-assisted purification; phosphinyl auxiliary; reduction; α-amino ester; α-imino ester.