Abstract: A benzylamine derivative has a structure represented by the following formula (1): In a method for optical resolution of the benzylamine derivative, optically active mandelic acid is used as an optical resolving agent. In an optical resolution step in a production method of the optically active benzylamine derivative, an optically active (S)-benzylamine derivative represented by the formula (3) is precipitated as (S)-mandelic acid salt from a solution containing the benzylamine derivative and (S)-mandelic acid: wherein Ar represents an aryl group that has 6 to 15 carbon atoms and may have a substituent, and *1 represents an asymmetric carbon atom.

Abstract: Novel 4,5-bis(4-methoxyphenyl)-2-(pyrrol-2-yl)-thiazoles of the formula: ##STR1## wherein R.sup.1 is C.sub.1-4 alkyl, C.sub.2-4 alkenyl, C.sub.2-4 alkynyl, 2,2,2-trifluoroethyl, a group of the formula: --CH.sub.2 COOR.sup.2 R.sup.2 is C.sub.1-8 alkyl, C.sub.2-4 alkenyl, C.sub.2-4 alkynyl, or phenyl-C.sub.1-2 alkyl), or a group of the formula: --(CH.sub.2).sub.n --A--R.sup.3 (A is oxygen or sulfur, R.sup.3 is C.sub.1-4 alkyl or C.sub.2-4 alkenyl, and n is 1, 2 or 3), a process for the preparation of the compounds, and a pharmaceutical composition useful as a platelet aggregation inhibitor which comprises as an active ingredient the above 4,5-bis(4-methoxyphenyl)-2-(pyrrol-2-yl)thiazole compound in admixture with a conventional pharmaceutically acceptable carrier or diluent.