For the purpose of study on racemization of exo methine carbon atom of thiazoline, oxazoline or imidazoline ring, the following four compounds were synthesized from amino acid imino ether: 2-(1-benzyloxycarbonylaminoethyl)-2-thiazoline (I), methyl 2-(1- benzyloxycarbonylaminoethyl)-2-thiazoline-4-carboxylate (II), methyl 2-(1- benzyloxycarbonylaminoethyl)-2-oxazoline-4-carboxylate (III), and 2-(1- ...