Enantiospecific synthesis of isomers of AES, a new environmentally friendly chelating agent
摘要:
Three four-step enantiospecific syntheses of different diastereomers of AES, a new biodegradable chelating agent, are described. The stereocenters in each of the isomers are accessible from L- and D-malic and aspartic acids. (C) 2004 Elsevier Ltd. All rights reserved.
One-Pot Generation and Conversion of Trichloroacetimidates for the Racemization-Free Allylation and Benzylation of α-Hydroxyesters and the Enantiopure Synthesis of a Chiral Diglycole
O-Allylations and O-benzylations of alpha -hydroxy esters (3a-3c) are performed without racemization. The reagents applied, O-allyl- and O-benzyltrichloroacetimidate (5a, 5b) are prepared and converted in a one-pot-procedure. After protection by benzylation (S)-(-)-ethyl lactate (3a) is converted by a sequence of carbonyl reduction, alcohol activation, ether formation, and deprotection to the optically active diglycole derivative 1a.