Crystal structure of ethyl 4-(2,4-di­chloro­phen­yl)-2-methyl-4H-benzo[4,5]thia­zolo[3,2-a]pyrimidine-3-carboxyl­ate

T Sankar; S Naveen; N K Lokanath; K Gunasekaran

doi:10.1107/S2056989015007033

. 2015 Apr 15;71(Pt 5):o306–o307. doi: 10.1107/S2056989015007033

Crystal structure of ethyl 4-(2,4-dichlorophenyl)-2-methyl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidine-3-carboxylate

T Sankar ^a, S Naveen ^b, N K Lokanath ^c, K Gunasekaran ^a,^*

PMCID: PMC4420040 PMID: 25995918

Abstract

In the title compound, C₂₀H₁₆Cl₂N₂O₂S, the pyrimidine ring has a screw-boat conformation. The attached dichlorophenyl ring is twisted at an angle of 89.29 (13)° with respect to the pyrimidine ring mean plane. The benzothiazole group is approximately planar (r.m.s. deviation = 0.008 Å) and inclined to the pyrimidine ring mean plane by 3.04 (10)°. The carboxylate group assumes an extended conformation with respect to the pyrimidine ring, which can be seen from the O=C—O—C torsion angle of 3.2 (4) °. In the crystal, molecules are linked via C—H⋯O and C—H⋯N hydrogen bonds, forming slabs lying parallel to (100).

Keywords: crystal structure, pyrimidine, benzothiazole, C—H⋯O hydrogen bonds, C—H⋯N hydrogen bonds

Related literature

For general background and literature on the biological properties of pyrimidine derivatives, see: Kumar et al. (2002 ▸; Baraldi et al. (2002 ▸); Nasr & Gineinah (2002 ▸). graphic file with name e-71-0o306-scheme1.jpg

Experimental

Crystal data

C₂₀H₁₆Cl₂N₂O₂S
M _r = 419.31
Monoclinic,
a = 38.654 (8) Å
b = 11.787 (3) Å
c = 8.774 (2) Å
β = 102.415 (14)°
V = 3904.1 (15) Å³
Z = 8
Cu Kα radiation
μ = 4.14 mm⁻¹
T = 296 K
0.30 × 0.27 × 0.25 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▸) T _min = 0.370, T _max = 0.424
10089 measured reflections
3114 independent reflections
2519 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.139
S = 1.04
3114 reflections
246 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▸); cell refinement: SAINT (Bruker, 2008 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▸) and Mercury (Macrae et al., 2008 ▸); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▸).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989015007033/su5114sup1.cif

e-71-0o306-sup1.cif^{(18.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015007033/su5114Isup2.hkl

e-71-0o306-Isup2.hkl^{(152.9KB, hkl)}

Click here for additional data file.^{(7KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015007033/su5114Isup3.cml

Click here for additional data file.^{(1.5MB, tif)}

. DOI: 10.1107/S2056989015007033/su5114fig1.tif

The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Click here for additional data file.^{(3.3MB, tif)}

c . DOI: 10.1107/S2056989015007033/su5114fig2.tif

The crystal packing of the molecules viewed down the c axis.

CCDC reference: 1056200

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C5H5N1ⁱ	0.93	2.59	3.515(4)	176
C16H16O24ⁱⁱ	0.93	2.53	3.180(4)	128

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

Acknowledgments

The authors are thankful to the Institution of Excellence, University of Mysore, for providing the single-crystal X-ray diffraction facility.

supplementary crystallographic information

S1. Structural commentary

Many pyrimidine derivatives are reported to have anti-bacterial, anti-tumor and anti-viral activities (Kumar et al., 2012; Baraldi et al., 2002; Nasr et al., 2002). In view of their important properties we synthesized the title compound and report herein on its crystal structure.

The molecular structure of the title compound is shown in Fig. 1. The pyrimidine ring [N1/C13/C12/C11/N10/C2] has a screw-boat conformation and its mean plane is inclined to the planar benzothiazole group [S3/C2/N10/C4—C9; r.m.s. deviation = 0.008 Å] by 3.04 (10) °. The dichlorophenyl ring [C15—C20] is twisted at an angle of 89.29 (13) ° with respect to the pyrimidine ring mean plane. The carboxylate group assumes an extended conformation with respect to the pyrimidine ring, which can be seen from the torsion angle O24—C23—O25—C26 = 3.2 (4) °.

In the crystal, molecules are linked via C—H···O and C—H···N hydrogen bonds forming slabs lying parallel to (100); see Table 1 and Fig. 2.

S2. Synthesis and crystallization

A mixture of 2,4-dichloro benzaldehyde was treated with ethyl acetoacetate and 2-aminobenzothiazole in the presence of ammonium acetate in ethanol. The mixture was gently warmed in a water bath at 353 K until the colour changed and it was then kept aside overnight at room temperature. The completion of reaction was monitored by TLC. The solid obtained was separated and purified by means of column chromatography using hexane and ethyl acetate as eluent. The sample was recrystallized using a 1:1 mixture of ethanol and THF, yielding yellow block-like crystals.

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were positioned geometrically and allowed to ride on their parent atoms: C—H = 0.93-0.98 Å with U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for other H atoms.