Patent ID: 8524943

Claim:
A process for preparing trans-4-amino-2-cyclopentene-1-carboxylic acid derivatives represented by formula 1, comprising: a) providing a composition comprising a compound of formula A, having components present in both cis- and trans-structures, wherein R 1 is an alkyl or aryl group having up to 12 carbon atoms, in a solvent; b) combining with an amine to form salts, wherein some salt precipitates but the salt of a trans-structure of compound A remains in the solution in excess of the amount of the salt of the cis-structure of compound A remaining in the solution; c) separating the precipitate from the solution; d) adding acid to the solution to re-form carboxylic acids from the salts in the solution; e) isolating the compound 1, which is the trans-structure of compound A; and f) optionally, purifying the composition from e) to produce a diastereomeric excess of the trans-structure of compound A.