(S) or (R) ENANTIOMERS, METHOD OF PREPARING THEREOF, AND INTERMEDIATE PRODUCT Russian patent published in 1999 - IPC

FIELD: chemical industry. SUBSTANCE: present invention describes (S) or (R) enantiomer of compound of formula (IA) wherein AlK is alkyl having from to 3 carbon atoms and physiologically acceptable acid addition salt thereof. Enantiomers have pharmacological properties identical with those of trazodone but have reduced affinity with adrenergic receptors. Method of preparing compounds of formula (I) or acid addition salts thereof comprises reacting compound of formula (III) or alkaline metal salt thereof with piperazine compound of formula (II) wherein AlK is as defined above, and X is removable group from group containing chlorine, bromine and -O-SO₂-Z in which Z is alkyl or aryl. Compound (II) has absolute (R) or (S) configuration in the presence of suitable organic diluent or mixture of organic diluents at temperature from 40 C to boiling temperature of reaction mixture, and physiologically enantiomer is optionally formed. Present invention describes some novel intermediate compounds. EFFECT: improved properties of the enantiomers. 17 cl, 3 ex, 3 tbl