Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction.
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.
School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China.
Yiwen
Y
Xiong
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.
Haibo
H
Mei
School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China.
Lingmin
L
Wu
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.
Jianlin
J
Han
School of Chemistry and Chemical Engineering, State of Key Laboratory of Coordination, Nanjing University, Nanjing, 210093, China.
Yi
Y
Pan
Institute for Chemistry & BioMedical Sciences, Nanjing University, Nanjing, 210093, China ; Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, 79409-1061, USA.
Guigen
G
Li
group-assisted purification; phosphinyl auxiliary; reduction; α-amino ester; α-imino ester