Chemoenzymatic resolution of epimeric cis 3-carboxycyclopentylglycine derivatives

Epimeric 3-carboxycyclopentylglycines were efficiently prepd. by a sequence of Diels-Alder and retro-Claisen reactions. The synthesis incorporates a concise and inexpensive chemoenzymic resoln. of the racemic 3-carboxycyclopentyl-N-benzoylglycine Et esters, the N,O-protected derivs. of the amino acids. Systematic screening with different enzymes and microorganisms was performed to select a very efficient catalyst for the sepn. of the racemic mixts. The reaction conditions allowing deprotection of both ester and amino functions while avoiding epimerization processes were studied. The enantiomers were obtained in high enantiopurity and the abs. configuration of all stereocenters was unequivocally assigned