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Journal of Chemical Crystallography

, Volume 38, Issue 4, pp 255–260 | Cite as

Low Temperature X-ray Crystallographic Structures of Two Lamotrigine Analogues: (I) 2-Methyl,3-amino, 5-imino-6-(2,3-dichlorophenyl)-1,2,4-triazine Water Solvate and (II) 2-Methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine Isethionate, Hemi-hydrate

  • Rex A. Palmer
  • Brian S. Potter
  • Michael J. Leach
  • Babur Z. Chowdhry
Original Paper

Abstract

The X-ray crystal structures of two lamotrigine derivatives (I) 2-methyl, 3-amino, 5-imino-6-(2, 3-dichlorophenyl)-1,2,4-triazine, C10H9Cl2N5, as the hemi hydrate and (II) 2-methyl,3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine, C10H10Cl2N5, as the isethionate-water solvate, have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are monoclinic and centrosymmetric, with (I) in space group C2/c, and (II) in space group P21/n. For (I) the unit cell dimensions are a = 19.5466(10), b = 7.5483(4), c = 15.7861(8) Å, β = 91.458(3)°, volume = 2328.4(2) Å3, Z = 8, density = 1.590 Mg/m3; for (II). For (II) the unit cell dimensions are a = 6.0566(2), b = 11.0084(4) c = 23.9973(9) Å, β = 92.587(3)°, volume = 1598.35(10) Å3, Z = 4, density = 1.597 Mg/m3. For (I) final R indices [I > 2sigma(I)] are R1 = 0.0356, wR2 = 0.0782 and R indices (all data) are R1 = 0.0424, wR2 = 0.0817. For (II) final R indices [I > 2sigma(I)] are R1 = 0.0380, wR2 = 0.0871 and R indices (all data) R1 = 0.0558, wR2 = 0.0949. Both structures have a molecule of water of crystallization and (II) also includes a solvated CH3SO3. Comparisons are made between the two structures. Structure (I) is very unusual in having a = NH group at position C5′ on the triazine ring. No other examples of this particular substitution, which is usually −NH2, have been reported.

Index Abstract

Rex A. Palmer, Brian S. Potter, Michael J Leach and Babur Z. Chowdhry

The crystal structures of (I) 2-methyl,3-amino, 5-imino-6-(2, 3-dichlorophenyl)-1, 2, 4-triazine, water solvate and (II) 2-methyl,3, 5-diamino-6-(2, 3-dichlorophenyl)-1, 2, 4-triazine isethionate water solvate are presented. The relative orientation of the two rings is shown to vary. Lamotrigine and analogues have been investigated for some time for their effects on the central nervous system. For example both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW 1003C87) are voltage-gated sodium channel blockers as well as blocking the release of the neurotransmitter glutamate [D. R. Riddall, M. J. Leach, J. Garthwaite, Mol. Pharmacol. 2006, 69 (1), 278.3], BW10003C87 (like lamotrigine) has been shown to exhibit excitatory amino acid antagonist activity similar to that of three conventional antiepileptic drugs phenytoin, carbamazepine and phenobarbital [R. Lingamaneni, H. C. Hemmings Jr., Epilepsy Res. 1993, 15, 101.]. BW 1003C87 has also been shown [B. S. Meldrum, J. H. Swan, M. J. Leach, M. H. Millan, R. Gwinn, K. Kadota, S. H Graham, J. Chen, R. P. Simon , Brain Res., 1992, 593, 1.] to reduce the release of glutamate evoked by veratrine in brain tissue, providing a therapeutic approach in both cerebral ischemia and epilepsy. This is one of a series of papers on the structures of lamotrigine analogues.

Keywords

Central nervous system drugs Triazines Lamotrigines Voltage gated Na+ channel inhibitors Crystal structures and drug design 

Notes

Acknowledgments

We thank Dr P. Barraclough (University of Greenwich) for the synthesis and provision of samples of (I) and (II). Low temperature X-ray intensity data were collected on the EPSRC single crystal X-ray data facility at Southampton University.

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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.School of Crystallography, Birkbeck CollegeUniversity of LondonLondonUK
  2. 2.Medway School of ScienceUniversity of Greenwich (Medway Campus)KentUK

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