Structure and absolute configuration of (–)-(3S,4R)-4-carboxy-1-[4-cyano-4-(4-fluorophenyl)cyclohexyl]-3-methyl-4-phenylpiperidinium bromide (levocabastine hydrobromide)

Abstract

Levocabastine is a potent H 1 antihistamine agent. Both the piperidine and cyclohexane rings in the title compound, C 26 H 30 FN 2 O 2 + .Br - , have conformations close to an ideal chair. The piperidine and fluorophenyl rings are posiboned equatorially on the cyclohexane ring, while the cyano group is oriented axially, resulting in a cis configuration. The phenyl moiety on the piperidine ring is in an equatorial orientation while the methyl and carboxyl substituents are placed axially. This corresponds to a trans configuration. The molecules are linked together in the c direction by N-H...Br...H-O hydrogen bonds