Process for the preparation of enantiomerically pure imidazolyl compounds

Abstract

The invention relates to a method for the preparation of an enantiomerically pure imidazolyl compound of the general formula ##STR1## wherein n is 0 or 1; m is 1 or 2; R.sub.1 is hydrogen, methyl or ethyl; and C* denotes a chiral centre; as well as its pharmaceutically acceptable acid addition salt; by a) adding a pyroglutamic acid in an optically active form to a solution of a racemic mixture of the above compound I, followed by separation of the crystallized acid addition salt of said mixture of enantiomers of compound I enriched in one enantiomer, from the mother liquor enriched in the other enantiomer b) when the crystallized acid addition salt is enriched in the undersired enantiomer, by then separating the mixture of enantiomers in the mother liquor from said optically active carboxylic acid, followed by addition of a racemic mixture of said carboxylic acid to a solution of the obtained mixture of isomers of I, and by separation of the crystallized acid addition salt of said mixture, enriched in the desired enantiomer, from the mother liquor, and (c) optionally recrystallizing the product until the desired enantiomeric purity is obtained, and by then (d) converting this acid-addition salt of the desired enantiomer to the desired enantiomerically pure imidazolyl compound of the general formula I or to its pharmaceutically acceptable acid addition salt.