PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 August 1; 65(Pt 8): o1987–o1988.
Published online 2009 July 25. doi:  10.1107/S1600536809027548
PMCID: PMC2977208

3-(2-Chloro­ethyl)-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one

Abstract

In the title mol­ecule, C11H11ClN2O, the pyrido[1,2-a]pyrimidine ring system is planar (maximum deviation = 0.0148 Å) and the methyl C and carbonyl O atoms are nearly coplanar to it. The chloro­ethyl side chain is in a synclinal conformation, nearly orthogonal to the pyrimidine ring, with a dihedral angle between the chloro­ethyl side chain and the pyrimidine ring of 88.5 (1)°. Weak inter­molecular C—H(...)N and C—H(...)Cl hydrogen bonds along with π–π inter­actions between the pyrimidine and pyridine rings [centroid–centroid distance is 3.538 (2) Å] form a three-dimensional network. The crystal is a racemic twin with a 0.68 (12):0.32 (12) domain ratio. MOPAC AM1 and density functional theory (DFT) theoretical calculations at the B3-LYP/6–311+G(d,p) level support these observations.

Related literature

For related structures, see: Blaton et al. (1995 [triangle]); Chen & He (2006 [triangle]); Elotmani et al. (2002 [triangle]); Jottier et al. (1992 [triangle]); Koval’chukova et al. (2004 [triangle]); Peeters et al. (1993 [triangle]); Ravikumar & Sridhar, (2006 [triangle]); Yu et al. (2007 [triangle]). For general background to heterofused pyrimidines, see: Baraldi et al. (2002 [triangle]); Bookser et al. (2005 [triangle]); Chen et al. (2004 [triangle]); La Motta et al. (2007 [triangle]); Gabbert & Giannini (1997 [triangle]); Goodacre et al. (2006 [triangle]); Hossain et al. (1997 [triangle]); Joseph & Burke (1993 [triangle]); Nikitin & Smirnov (1994 [triangle]); Sabnis & Rangnekar (1990 [triangle]); Wang et al. (2004 [triangle]); White et al. (2004 [triangle]). For the synthesis, see: Toche et al. (2008 [triangle]). For GAUSSIAN03 theoretical calculations, see: Becke (1988 [triangle], 1993 [triangle]); Frisch et al. (2004 [triangle]); Hehre et al. (1986 [triangle]); Lee et al. (1988 [triangle]); Schmidt & Polik (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o1987-scheme1.jpg

Experimental

Crystal data

  • C11H11ClN2O
  • M r = 222.67
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1987-efi1.jpg
  • a = 4.2546 (4) Å
  • b = 11.6274 (10) Å
  • c = 20.604 (2) Å
  • V = 1019.27 (17) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.35 mm−1
  • T = 110 K
  • 0.51 × 0.35 × 0.12 mm

Data collection

  • Oxford Diffraction Gemini R CCD diffractometer
  • Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 [triangle]) T min = 0.835, T max = 0.959
  • 4613 measured reflections
  • 3089 independent reflections
  • 2607 reflections with I > 2σ(I)
  • R int = 0.054

Refinement

  • R[F 2 > 2σ(F 2)] = 0.065
  • wR(F 2) = 0.181
  • S = 1.11
  • 3089 reflections
  • 138 parameters
  • H-atom parameters constrained
  • Δρmax = 0.99 e Å−3
  • Δρmin = −0.52 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1103 Friedel pairs
  • Flack parameter: 0.32 (12)

Data collection: CrysAlisPro (Oxford Diffraction, 2007 [triangle]); cell refinement: CrysAlisPro; data reduction: CrysAlisPro; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809027548/ci2827sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809027548/ci2827Isup2.hkl

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

Acknowledgments

QNMHA thanks the University of Mysore for use of its research facilities. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.

supplementary crystallographic information

Comment

Heterofused pyrimidines exhibit promising antiviral (Hossain et al. 1997), antibacterial (Sabnis & Rangnekar, 1990), anti-AIDS (Joseph & Burke, 1993), and antinociceptive (Bookser et al. 2005) activities. Fused pyrimidines are extensively used in neurology, particularly in the treatment of neurodegenerative disorders such as Parkinson's disease (Baraldi et al. 2002), antianxiety disorders (Goodacre et al. 2006) and depression (Chen et al. 2004). Fused pyrimidines are selective inhibitors for multidrug resistance (MDR) (Wang et al. 2004). A review on the synthesis, chemical and biological properties of pyrido[1,2-a]pyrimidines is described (Nikitin & Smirnov, 1994). Pyrido[1,2-a]pyrimidin-4-one derivatives as a novel class of selective aldose reductase inhibitors exhibiting antioxidant activity has been reported (La Motta et al. 2007). The synthesis and anticonvulsant evaluation of some new 2-substituted-3-arylpyrido[2,3-d]pyrimidinones have also been reported (White et al. 2004). The crystal structures of 3-{2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)piperidino]ethyl}-6,7,8,9- tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (risperidone) (Peeters et al. 1993), 3-{2-[4-(4-fluorobenzoyl)piperidino]ethyl}-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (Pirenperone) (Blaton et al. 1995), 5-methyl-2-morpholino-3-p-tolyl-8,9,10,11-tetrahydro-2-benzothieno[2', 3':6,5]pyrido[4,3-d]pyrimidin-4(3H)-one (Chen & He, 2006), 3-{2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]ethyl}-2,9- dimethyl-4H-pyrido[1,2-a]pyrimidin-4-one (Ocaperidone) (Jottier et al. 1992), 2-methyl-3-(3-methyl-1H-pyrazol-5-yl)pyrido[1,2-a]pyrimidin-4-one (Elotmani et al. 2002), 2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-one and bis(2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-onium) perchlorate (Koval'chukova et al. 2004), 3-(2-chloroethyl)-2-methyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a] pyrimidin-1-ium chloride (Ravikumar & Sridhar, 2006) and 9-(4-methoxybenzoyl)-1,2,3,4-tetrahydro-6H-pyrido[1,2-a]pyrimidin-6-one (Yu et al. 2007) have also been reported.

The title compound, (I), is an intermediate in the synthesis of risperidone, which is a potent antipsychotic agent, especially useful for treating schizophrenia (Gabbert & Giannini, 1997). In view of the importance of (I), the present paper describes its crystal structure.

The overall molecular geometry of (I), including bond distances and angles, is in good agreement with related structures (Blaton et al. 1995; Jottier et al. 1992; Peeters et al. 1993; Ravikumar & Sridhar, 2006). It consists of a pyridine ring fused to a substituted pyrimidine ring creating a planar ring system (maximum deviation, C1, = -0.0148Å) with the methyl C and carbonyl O atoms nearly coplanar to the pyrimidine ring (Torsion angles C1-C9-C7-C8 = 177.6 (3)° ; C2-N1-C1-O = -2.5 (4)° (Fig. 1). The sum of the angles aroumd N1 is 360.0 (5)° indicating sp2 hybridization. The chloroethyl side chain is in a synclinal (-sc) conformation (C1—C9—C10—C11 torsion angle = -86.6 (3)°), nearly orthogonal to the pyrimidine ring, with a dihedral angle separation between the C10/C11/Cl group and the pyrimidine ring of 88.5 (1)°.

While no classic hydrogen bonds are observed, a weak intermolecular hydrogen bond interaction exists between atom C5 from the pyridine ring and N2 from a nearby pyrimidine ring (Table 1 and Fig. 2). In addition, a weak intermolecular interaction between atom C2 from the pyrimidine ring and Cl from the substituted pyrimidine group also occurs, each influencing crystal packing and, therefore, resulting in a three-dimensional network (Fig. 2). In addition, π-π interactions between N1/C1/C9/C7/N2/C6 (centroid Cg1) and N1/C2-C6 (centroid Cg2) rings of molecules at (x, y, z) and (1+x, y, z), with a Cg1···Cg2 distance of 3.538 (2) Å, provide additional stability to the crystal packing. The crystal is a racemic twin with domains of 0.68 (12) and 0.32 (12).

In support of these observations, a MOPAC AM1 (Schmidt & Polik, 2007) and density functional theory (DFT) geometry optimized theoretical calculation (Schmidt & Polik, 2007) with the GAUSSIAN03 program package (Frisch et al. 2004) employing the B3-LYP (Becke 3 parameter Lee-Yang-Parr) exchange correlation functional, which combines the hybrid exchange functional of Becke (Becke, 1988, 1993) with the gradient-correlation functional of Lee, Yang and Parr (Lee et al. 1988) and the 6–311+G(d,p) basis set (Hehre et al. 1986), was performed on (I) utilizing starting geometries taken from the X-ray refinement data. In both calculations the resulting bond distances and angles remained relatively constant. However, the C9—C10—C11—Cl torsion angle decreased by 3.2 (1)° to 175.4 (3)° (MOPAC) and 0.07° to 178.5 (7)° (DFT) and the dihedral angle between the C10/C11/Cl group and the pyrimidine ring decreased by 2.3 (8)° to 86.1 (3)° (MOPAC) and by 8.3 (6)° to 80.1 (5)° (DFT), respectively.

In summary, it is clear that the collection of weak intermolecular hydrogen bond interactions and π-π intermolecular interactions do play a role in stabilizing crystal packing of (I).

Experimental

The title compound was synthesized following the reported procedure (Toche et al. 2008). Pale yellow crystals of compound (I) were obtained by slow evaporation from ethyl acetate solution (m.p. 405–408 K). Analytical data: Found (calculated): C %: 59.28 (59.33); H%: 4.97 (4.98); N%: 12.54 (12.58).

Refinement

All of the H atoms were placed in their calculated positions and then refined using the riding model with C—H = 0.95–0.99 Å, and with Uiso(H) = 1.18–1.50Ueq(C).

Figures

Fig. 1.
Molecular structure of (I), showing the atom labeling scheme and 50% probability displacement ellipsoids.
Fig. 2.
Packing diagram of (I), viewed down the b axis. Dashed lines indicate weak C5—H5A···N2 and C2—H2A···Cl intermolecular interactions.

Crystal data

C11H11ClN2OF(000) = 464
Mr = 222.67Dx = 1.451 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2755 reflections
a = 4.2546 (4) Åθ = 4.8–32.6°
b = 11.6274 (10) ŵ = 0.35 mm1
c = 20.604 (2) ÅT = 110 K
V = 1019.27 (17) Å3Plate, colorless
Z = 40.51 × 0.35 × 0.12 mm

Data collection

Oxford Diffraction Gemini R CCD diffractometer3089 independent reflections
Radiation source: Enhance (Mo) X-ray Source2607 reflections with I > 2σ(I)
graphiteRint = 0.054
Detector resolution: 10.5081 pixels mm-1θmax = 32.6°, θmin = 4.9°
[var phi] and ω scansh = −3→6
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007)k = −17→16
Tmin = 0.835, Tmax = 0.959l = −30→27
4613 measured reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.065H-atom parameters constrained
wR(F2) = 0.181w = 1/[σ2(Fo2) + (0.1108P)2 + 0.2652P] where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max = 0.001
3089 reflectionsΔρmax = 0.99 e Å3
138 parametersΔρmin = −0.51 e Å3
0 restraintsAbsolute structure: Flack (1983), 1103 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.32 (12)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
Cl0.49448 (19)0.87358 (6)0.12093 (3)0.02056 (18)
O0.1937 (6)1.09071 (18)0.30555 (10)0.0240 (5)
N1−0.0403 (6)0.9961 (2)0.39118 (10)0.0150 (4)
N20.0097 (7)0.79306 (19)0.40322 (11)0.0172 (4)
C10.1541 (7)0.9982 (2)0.33357 (13)0.0151 (5)
C2−0.1616 (9)1.0994 (2)0.41318 (14)0.0207 (6)
H2A−0.11161.16850.39090.025*
C3−0.3506 (8)1.1032 (3)0.46596 (15)0.0231 (6)
H3A−0.43541.17440.48030.028*
C4−0.4212 (7)0.9999 (3)0.49970 (14)0.0211 (6)
H4A−0.55301.00190.53690.025*
C5−0.3006 (8)0.8986 (2)0.47886 (13)0.0191 (5)
H5A−0.34770.82990.50190.023*
C6−0.1033 (7)0.8935 (2)0.42262 (13)0.0147 (5)
C70.1973 (8)0.7917 (2)0.34977 (13)0.0155 (5)
C80.3087 (9)0.6735 (2)0.33069 (16)0.0239 (6)
H8A0.25810.61880.36530.036*
H8B0.53660.67500.32380.036*
H8C0.20380.64990.29050.036*
C90.2748 (7)0.8891 (2)0.31499 (12)0.0146 (5)
C100.4766 (9)0.8869 (2)0.25437 (12)0.0182 (5)
H10A0.62680.82200.25670.022*
H10B0.59830.95920.25110.022*
C110.2671 (7)0.8733 (3)0.19491 (13)0.0201 (5)
H11A0.11300.93710.19360.024*
H11B0.14890.80020.19820.024*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cl0.0233 (3)0.0253 (3)0.0132 (3)−0.0031 (3)0.0030 (3)−0.0001 (2)
O0.0323 (13)0.0185 (9)0.0214 (10)−0.0029 (9)0.0024 (10)0.0048 (8)
N10.0188 (11)0.0144 (8)0.0118 (9)0.0013 (9)−0.0009 (9)0.0005 (7)
N20.0200 (10)0.0157 (8)0.0160 (10)−0.0002 (12)−0.0001 (11)0.0019 (7)
C10.0168 (12)0.0163 (11)0.0122 (11)−0.0028 (11)−0.0005 (10)0.0002 (9)
C20.0286 (15)0.0163 (11)0.0173 (13)0.0039 (12)0.0000 (12)−0.0001 (9)
C30.0259 (15)0.0235 (13)0.0198 (14)0.0058 (13)−0.0013 (12)−0.0054 (10)
C40.0198 (14)0.0300 (14)0.0135 (12)0.0026 (12)0.0017 (10)−0.0019 (10)
C50.0196 (13)0.0234 (12)0.0142 (12)−0.0029 (12)0.0018 (11)0.0028 (10)
C60.0178 (11)0.0146 (11)0.0118 (11)−0.0013 (9)−0.0029 (9)0.0017 (8)
C70.0194 (13)0.0125 (10)0.0146 (11)0.0001 (11)−0.0022 (11)−0.0001 (9)
C80.0282 (16)0.0167 (11)0.0267 (15)0.0015 (13)0.0028 (14)−0.0022 (10)
C90.0133 (11)0.0183 (11)0.0124 (12)−0.0020 (10)−0.0004 (9)0.0005 (9)
C100.0164 (12)0.0245 (12)0.0138 (11)−0.0008 (13)0.0011 (10)0.0003 (9)
C110.0178 (12)0.0305 (13)0.0119 (11)−0.0035 (12)0.0019 (10)−0.0012 (11)

Geometric parameters (Å, °)

Cl—C111.805 (3)C5—C61.432 (4)
O—C11.232 (3)C5—H5A0.95
N1—C21.383 (4)C7—C91.381 (4)
N1—C61.384 (3)C7—C81.505 (4)
N1—C11.447 (3)C8—H8A0.98
N2—C61.325 (3)C8—H8B0.98
N2—C71.360 (4)C8—H8C0.98
C1—C91.421 (4)C9—C101.516 (4)
C2—C31.353 (5)C10—C111.523 (4)
C2—H2A0.95C10—H10A0.99
C3—C41.420 (5)C10—H10B0.99
C3—H3A0.95C11—H11A0.99
C4—C51.355 (4)C11—H11B0.99
C4—H4A0.95
C2—N1—C6121.5 (2)N2—C7—C8114.0 (2)
C2—N1—C1117.9 (2)C9—C7—C8122.6 (3)
C6—N1—C1120.6 (2)C7—C8—H8A109.5
C6—N2—C7117.9 (2)C7—C8—H8B109.5
O—C1—C9127.1 (3)H8A—C8—H8B109.5
O—C1—N1118.5 (3)C7—C8—H8C109.5
C9—C1—N1114.4 (2)H8A—C8—H8C109.5
C3—C2—N1120.9 (3)H8B—C8—H8C109.5
C3—C2—H2A119.5C7—C9—C1120.4 (2)
N1—C2—H2A119.5C7—C9—C10123.3 (2)
C2—C3—C4119.4 (3)C1—C9—C10116.3 (2)
C2—C3—H3A120.3C9—C10—C11109.5 (3)
C4—C3—H3A120.3C9—C10—H10A109.8
C5—C4—C3120.0 (3)C11—C10—H10A109.8
C5—C4—H4A120.0C9—C10—H10B109.8
C3—C4—H4A120.0C11—C10—H10B109.8
C4—C5—C6120.9 (3)H10A—C10—H10B108.2
C4—C5—H5A119.5C10—C11—Cl111.4 (2)
C6—C5—H5A119.5C10—C11—H11A109.3
N2—C6—N1123.3 (2)Cl—C11—H11A109.3
N2—C6—C5119.6 (2)C10—C11—H11B109.3
N1—C6—C5117.2 (2)Cl—C11—H11B109.3
N2—C7—C9123.4 (2)H11A—C11—H11B108.0
C2—N1—C1—O−2.5 (4)C4—C5—C6—N2−179.6 (3)
C6—N1—C1—O177.1 (3)C4—C5—C6—N10.5 (4)
C2—N1—C1—C9178.7 (3)C6—N2—C7—C9−0.1 (4)
C6—N1—C1—C9−1.8 (4)C6—N2—C7—C8−178.8 (3)
C6—N1—C2—C3−0.9 (5)N2—C7—C9—C1−1.0 (4)
C1—N1—C2—C3178.6 (3)C8—C7—C9—C1177.6 (3)
N1—C2—C3—C41.0 (5)N2—C7—C9—C10−178.2 (3)
C2—C3—C4—C5−0.3 (5)C8—C7—C9—C100.4 (5)
C3—C4—C5—C6−0.5 (5)O—C1—C9—C7−176.9 (3)
C7—N2—C6—N10.2 (4)N1—C1—C9—C71.8 (4)
C7—N2—C6—C5−179.7 (3)O—C1—C9—C100.6 (4)
C2—N1—C6—N2−179.7 (3)N1—C1—C9—C10179.3 (2)
C1—N1—C6—N20.8 (4)C7—C9—C10—C1190.7 (3)
C2—N1—C6—C50.2 (4)C1—C9—C10—C11−86.6 (3)
C1—N1—C6—C5−179.3 (3)C9—C10—C11—Cl178.6 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C5—H5A···N2i0.952.503.394 (3)157
C2—H2A···Clii0.952.903.559 (3)128

Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) −x, y+1/2, −z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CI2827).

References

  • Baraldi, P. G., Cacciari, B., Romagnoli, R., Spalluto, G., Monopoli, A., Ongini, E., Varani, K. & Borea, P. A. (2002). J. Med. Chem.45, 115–126. [PubMed]
  • Becke, A. D. (1988). Phys. Rev.A38, 3098–100. [PubMed]
  • Becke, A. D. (1993). J. Chem. Phys.98, 5648–5652.
  • Blaton, N. M., Peeters, O. M. & De Ranter, C. J. (1995). Acta Cryst. C51, 533–535.
  • Bookser, B. C., Ugarkar, B. G., Matelich, M. C., Lemus, R. H., Alla, M., Tsuchiya, M., Nakane, M., Nagahisa, A., Wiesner, J. B. & Erion, M. D. (2005). J. Med. Chem.48, 7808–7820. [PubMed]
  • Chen, C., Chen, C., Wilcoxen, K. M., Huang, C. Q., Xie, Y.-F., McCarthy, J. R., Webb, T. R., Zhu, Y.-F., Saunders, J., Liu, X.-J., Chen, T.-K., Bozigian, H. & Grigoriadis, D. E. (2004). J. Med. Chem.47, 4787–4798. [PubMed]
  • Chen, H.-L. & He, H.-W. (2006). Acta Cryst. E62, o1226–o1227.
  • Elotmani, B., Elmahi, M., Essassi, E. M. & Pierrot, M. (2002). Acta Cryst. E58, o388–o389.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Frisch, M. J., et al. (2004). GAUSSIAN03 Gaussian Inc., Wallingford, CT 06492, USA.
  • Gabbert, J. F. & Giannini, A. J. (1997). Am. J. Ther.4, 159–164. [PubMed]
  • Goodacre, S. C., Street, L. J., Hallett, D., Crawforth, J. M., Kelly, S., Owens, A. P., Blackaby, W. P., Lewis, R. T., Stanley, J., Smith, A. J., Ferris, P., Sohal, B., Cook, S. M., Pike, A., Brown, N., Wafford, K. A., Marshall, G., Castro, J. L. & Atack, J. R. (2006). J. Med. Chem.49, 35–38. [PubMed]
  • Hehre, W. J., Random, L., von Schleyer, P. R. & Pople, J. A. (1986). In Ab Initio Molecular Orbital Theory New York: Wiley.
  • Hossain, N., Rozenski, J., De Clercq, E. & Herdewijn, P. (1997). J. Org. Chem.62, 2442–2447. [PubMed]
  • Joseph, S. & Burke, J. M. (1993). J. Biol. Chem.268, 24515–24518. [PubMed]
  • Jottier, W. I., De Winter, H. L., Peeters, O. M., Blaton, N. M. & De Ranter, C. J. (1992). Acta Cryst. C48, 1827–1830.
  • Koval’chukova, O. V., Mordovina, N. I., Kuz’mina, N. E., Nikitin, S. V., Zaitsev, B. E., Strashnova, S. B. & Palkina, K. K. (2004). Crystallogr. Rep.49, 792–797.
  • La Motta, C., Sartinit, S., Mugnaini, L., Simorini, F., Taliani, S., Salerno, S., Marini, A. M., Da Settimo, F., Lavecchia, A., Novellino, E., Cantore, M., Failli, P. & Ciuffi, M. (2007). J. Med. Chem.50, 4917–4927. [PubMed]
  • Lee, C., Yang, W. & Parr, R. G. (1988). Phys. Rev. B, 37, 785–789. [PubMed]
  • Nikitin, S. V. & Smirnov, L. D. (1994). Chem. Heter. Copm.30, 507–522.
  • Oxford Diffraction (2007). CrysAlisPro and CrysAlis RED Oxford Diffraction Ltd, Abingdon, England.
  • Peeters, O. M., Blaton, N. M. & De Ranter, C. J. (1993). Acta Cryst. C49, 1698–1700.
  • Ravikumar, K. & Sridhar, B. (2006). Acta Cryst. E62, o3730–o3731.
  • Sabnis, R. W. & Rangnekar, D. W. (1990). Indian J. Technol.28, 54–58.
  • Schmidt, J. R. & Polik, W. F. (2007). WebMO Pro WebMO, LLC: Holland, MI, USA. URL: http://www.webmo.net.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Toche, R. B., Ghotekar, B. K., Kazi, M. A., Patil, S. P. & Jachak, M. N. (2008). Schol. Res. Exch. doi:10.3814/2008/434329, 1–5.
  • Wang, S., Folkes, A., Chuckowree, I., Cockcroft, X., Sohal, S., Miller, W., Milton, J., Wren, S. P., Vicker, N., Depledge, P., Scott, J., Smith, L., Jones, H., Mistry, P., Faint, R., Thompson, D. & Cocks, S. (2004). J. Med. Chem.47, 1329–1338. [PubMed]
  • White, D. C., Greenwood, D. C., Downey, A. L., Bloomquis, J. R. & Wolfe, J. F. (2004). Bioorg. Med. Chem.12, 5711–5717. [PubMed]
  • Yu, C.-Y., Yuan, X.-N. & Huang, Z.-T. (2007). Acta Cryst. E63, o3186.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography