2-Amino-4-(4-bromo­phen­yl)-8-trifluoro­methyl-3,4-dihydropyrimido[1,2-a][1,3,5]triazin-6(5H)-one

Anton V Dolzhenko; Nikhil Sachdeva; Geok Kheng Tan; Lip Lin Koh; Wai Keung Chui

doi:10.1107/S1600536809007612

. 2009 Mar 6;65(Pt 4):o684. doi: 10.1107/S1600536809007612

2-Amino-4-(4-bromophenyl)-8-trifluoromethyl-3,4-dihydropyrimido[1,2-a][1,3,5]triazin-6(5H)-one¹

Anton V Dolzhenko ^a,^*, Nikhil Sachdeva ^a, Geok Kheng Tan ^b, Lip Lin Koh ^b, Wai Keung Chui ^a

PMCID: PMC2969032 PMID: 21582426

Abstract

The title compound, C₁₃H₉BrF₃N₅O, crystallizes with two independent molecules in the asymmetric unit. The pyrimidine rings of the molecules are planar [maximum deviations 0.053 (3) and 0.012 (3) Å], while the triazine rings adopt flattened half-boat conformations with the p-bromophenyl rings in the flagpole positions. The crystal packing is stabilized by a three-dimensional network of intermolecular N—H⋯N, N—H⋯O and N—H⋯F hydrogen bonds.

Related literature

For the crystal structure of 7,7-dimethyl-2-phenyl-6,7-dihydro-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amine, see: Dolzhenko et al. (2007 ▶). For the preparation of benzo-fused analogues, see: Dolzhenko et al. (2008a ▶). For the previous report in this series, see: Dolzhenko et al. (2008b ▶).

Experimental

Crystal data

C₁₃H₉BrF₃N₅O
M _r = 388.16
Orthorhombic,
a = 10.0531 (4) Å
b = 29.9108 (13) Å
c = 10.1945 (4) Å
V = 3065.4 (2) Å³
Z = 8
Mo Kα radiation
μ = 2.73 mm⁻¹
T = 223 K
0.46 × 0.34 × 0.20 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ▶) T _min = 0.367, T _max = 0.612 (expected range = 0.348–0.580)
20728 measured reflections
6287 independent reflections
4979 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.138
S = 1.04
6287 reflections
432 parameters
16 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.50 e Å⁻³
Δρ_min = −0.74 e Å⁻³
Absolute structure: Flack (1983 ▶), 2044 Friedel pairs
Flack parameter: 0.011 (10)

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536809007612/ng2543sup1.cif

e-65-0o684-sup1.cif^{(29.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809007612/ng2543Isup2.hkl

e-65-0o684-Isup2.hkl^{(307.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯N2ⁱ	0.87 (2)	2.15 (2)	3.005 (5)	171 (5)
N5—H5A⋯O2ⁱⁱ	0.895 (14)	2.09 (3)	2.905 (5)	152 (5)
N5—H5B⋯N4ⁱ	0.892 (14)	2.25 (2)	3.095 (6)	159 (5)
N5—H5B⋯F1ⁱ	0.892 (14)	2.46 (4)	3.054 (5)	124 (4)
N6—H6N⋯N7ⁱⁱⁱ	0.902 (19)	2.10 (3)	2.967 (5)	160 (5)
N10—H10A⋯O1	0.89 (2)	2.03 (3)	2.885 (5)	162 (5)
N10—H10B⋯N9ⁱⁱⁱ	0.90 (2)	2.15 (2)	3.041 (5)	171 (5)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

This work was supported by the National Medical Research Council, Singapore (grant Nos. NMRC/NIG/0019/2008 and NMRC/NIG/0020/2008).

supplementary crystallographic information

Comment

The title compound was synthesized via thermal cyclocondensation of 6-oxo-4-trifluoromethyl-1,6-dihydropyrimidin-2-yl guanidine with p-bromobenzaldehyde (Fig.1) using the methodology that we successfully applied previously for the preparation of its benzofused analogues (Dolzhenko et al., 2008a). In general, the synthesized compound might be involved in tautomerism with four possible tautomers (Fig. 2). However, only one tautomeric form viz. 2-amino-4-(4-bromophenyl)-8-trifluoromethyl-3,4-dihydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one was found in the crystal.

The compound crystallized with two independent molecules (A and B) in the asymmetric unit (Fig. 3). The pyrimidine rings in the molecules are planar with maximum deviations 0.0525 (26) Å (C3) and 0.0118 (32) Å (C18) from the planes C3/N3/C4—C6/N4 and C16/N8/C17—C19/N9 of molecules A and B, respectively. Similarly to structurally related 7,7-dimethyl-2-phenyl-6,7-dyhydro-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amine (Dolzhenko et al., 2007), the triazine rings in the molecules adopt flattened half-boat conformations with atoms N2 and N7 at the sterns and sp³-hybridized atoms C1 and C14 at the bows with p-bromophenyl rings as flagpoles. However, the molecules are significantly different in the geometry at bridgehead nitrogen atoms (N3 and N8) and sp³-hybridized atoms C1 and C14 of the triazine rings.The torsion angles C4—N3—C1—N1 and C17—N8—C14—N6 are 136.7 (4)° and 150.4 (3)°, respectively. In molecule B, the bond N8—C14 is located almost in the phenyl ring (C21—C26) plane: the torsion angle N8—C14—C21—C26 is 2.6 (5)°. The corresponding torsion angle N3—C1—C8—C9 of molecule A is 42.5 (6)°. The N1—C2, N2—C2, N5—C2 bond distances in A and N6—C15, N7—C15, N10—C15 in B are similar that suggests guanidine-like electron delocalization in N1/N2/N5/C2 and N6/N7/N10/C15 fragments of the molecules.

The crystal packing is stabilized by three-dimensional network of intramolecular N—H···N, N—H···O and N—H···F hydrogen bonds (Table 1, Fig. 4).

Experimental

2-Amino-4-(4-bromophenyl)-8-trifluoromethyl-3,4-dihydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one was synthesized from 6-oxo-4-trifluoromethyl-1,6-dihydropyrimidin-2-yl guanidine and p-bromobenzaldehyde according to general method reported by Dolzhenko et al. (2008a). Single crystals suitable for crystallographic analysis were grown by slow evaporation of the solution in ethyl acetate / methanol.