MONITORING OF OPTICAL ISOMERS OF SOME CONFORMATIONALLY CONSTRAINED AMINO-ACIDS WITH TETRAHYDROISOQUINOLINE OR TETRALINE RING STRUCTURES .2.

Conformationally constrained amino acids were synthesized in chiral or racemic forms: D- and L-1,2,3,4-tetrahydroisoquinoline-3-carboxylic a cid (Tie), the erythro-D,L-4-methyl analogue, D- and ydroxy-1,2,3,4-te trahydroisoquinoline-3-carboxylic acid, D- and 8-diiodo-1,2,3,4-tetrah ydroisoquinoline-3-carboxyl acid, D,L-2-aminotetraline-2-carboxylic ac id, D,L-6-hydroxy-2-aminotetraline-2-carboxylic acid and D,L-6-methoxy -2-aminotetraline-2-carboxylic acid. The optical isomers were characte rized and identified by applying precolumn derivatization with chiral reagents (1-fluoro-2,4-dinitrophenyl-5-L-alanine amide and 2,3,4,6-tet ra-O-acetyl-beta-D-glucopyranosyl isothiocyanate) and enzymatic digest ion with L-amino acid oxidase, carboxypeptidase A and alpha-chymotryps in. The HPLC conditions (pH, eluent composition and different buffers) were varied to obtain optimum separations.