Synthesis of the constrained glutamate analogues (2S,1′R,2′R)- and (2S,1′S,2′S)-2-(2′-carboxycyclobutyl)glycines L-CBG-II and L-CBG-I by enzymatic transamination

Optically pure trans-cyclobutane analogues of glutamic acid are prepared by highly selective enzymatic transamination of a single racemic trans-cyclobutane alpha-ketoglutaric acid derivative 5, which is synthesized in five steps from maleic anhydride. (2S,1'R,2'R)- and (2S,I'S,2'S)-2-(2'-carboxycyclobutyl)glycines L-CBG-II and L-CBG-I are obtained using aspartate aminotransferase (AAT) and branched chain aminotransferase (BCAT), respectively. (c) 2005 Elsevier Ltd. All rights reserved.