Crystal structure of levomepromazine maleate.

Gyula Tamás Gál,Nóra Veronika May,Petra Bombicz

doi:10.1107/s2056989016004916

Abstract

The asymmetric unit of the title salt, C19H25N2OS(+)·C4H3O4 (-) [systematic name: (S)-3-(2-meth-oxy-pheno-thia-zin-10-yl)-N,N,2-tri-methyl-propanaminium hydrogen maleate], comprises two (S)-levomepromazine cations and two hydrogen maleate anions. The conformations of the two cations are similar. The major difference relates to the orientation of the meth-oxy substituent at the pheno-thia-zine ring system. The crystal components form a three-dimensional supra-molecular network via N-H⋯O, C-H⋯O and C-H⋯π inter-actions. A comparison of the conformations of the levomepromazine cations with those of the neutral mol-ecule and similar protonated mol-ecules reveals significant conformational flexibility of the pheno-thia-zine ring system and the substituent at the pheno-thia-zine N atom.

Highlights

(S)-3-(2-methoxyphenothiazin-10-yl)-N,N,2-trimethylpropanaminium hydrogen maleate], comprises two (S)-levomepromazine cations and two hydrogen maleate anions
Levomepromazine maleate is a type of tranquilizer that is widely used as an important active pharmaceutical ingredient (API)
As a typical N-substituted phenothiazine antipsychotic, this API is able to block a variety of receptors

Summary

Chemical context

Levomepromazine maleate is a type of tranquilizer that is widely used as an important active pharmaceutical ingredient (API). As a typical N-substituted phenothiazine antipsychotic, this API is able to block a variety of receptors. The levomepromazine molecule is chiral and the (R)-() enantiomer is the medically active form. It is worth noting that the neutral (R)-levomepromazine molecule corresponds to the (S)-levomepromazine cation formed by protonation of its tertiary amino group, according to the. The crystal structure of neutral (R)-levomepromazine has been reported previously, including the determination of its absolute configuration (Sato et al.). As (R)-levomepromazine is generally sold in the form of its maleate salt, we report here the crystal structure of this compound and compare the conformation of neutral levomepromazine with those of its cationic forms

Structural commentary

Supramolecular features

Synthesis and crystallization

Refinement