The asymmetric synthesis of (2R,3R)- and (2R,3S)-3-methyl-aspartates via an enantiodiscrimination strategy

The enolate of (S)-N,N′-bis-(p-methoxybenzyl)-3-isopropylpiperazine-2,5-dione exhibits high levels of enantiodiscrimination towards racemic 2-bromo-propionate esters to afford adducts containing two new stereogenic centres which may be deprotected to afford (2R,3R)-3-methyl-aspartates or epimerised and then deprotected to afford (2R,3S)-3-methyl-aspartates as single diastereoisomers in high e.e

Enantiodiscrimination of racemic electrophiles by diketopiperazine enolates: asymmetric synthesis of methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates

Enolates of (S)-N,N′-bis-(p-methoxybenzyl)-3-iso-propylpiperazine-2,5-dione exhibit high levels of enantiodiscrimination in alkylations with (RS)-1-aryl-1-bromoethanes and (RS)-2-bromoesters, affording substituted diketopiperazines containing two new stereogenic centres in high de. Deprotection and hydrolysis of the resultant substituted diketopiperazines provides a route to the asymmetric synthesis of homochiral methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates in high de and ee. © 2006 Elsevier Ltd. All rights reserved