作者:Konstanze Gottwald、Dieter Seebach
DOI:10.1016/s0040-4020(98)01064-3
日期:1999.1
The kinetic resolution of azlactones by the Lewis-acid-mediated transfer of an isopropoxide ligand from the chiral ligand sphere of Ti-TADDOLate is described. The reactions proceed with in-situ racemization of the starting material to afford highly enantiomerically enriched N-benzoyl-amino acid isopropylesters (er > 95:5 after recrystallization). The absolute configuration of the major enantiomer of N-benzoyl-phenylalanine isopropyl ester and its analogs with other aromatic substituents was shown to be (S)-(+) when the (R,R)-Ti-TADDOLate was employed. Only benzyl-substituted azlactones can be opened enantioselectively by the method described here. (C) 1998 Elsevier Science Ltd. All rights reserved.