PURPOSE: To selectively prepare the enantiomers of 3-(4-phenyl-1-piperazinyl)-1,2- propanediol which are useful as an antitussive.
CONSTITUTION: Glycerol-1-tosylate which is optionally active is condensed with phenylpiperazine, preferably in benzene at the refluxing temp. to selectively obtain the enantiomers of 3-(4-phenyl-1-piperazinyl)-1,2-propanediol (dropropizine). By this method, the levorotatory isomer of dropropizine having the same antitussive effect as a racemic mixture but a small effect (side effect) on the central nervous system can be selectively produced from (-)-glycerol-1-tosylate, while the dextrorotatory isomer can be selectively produced from (+)- glycol-1-tosylate. The (-)-glycerol-1-tosylate is produced by converting (+)-1,2- isopropyliden-sn-glycerol into the corresponding tosylate and then removing the ketal from the tosylate.
JIANKARURO TONON
SARUBATOORE MARUANDORIINO
