organic compounds
H-thiazolo[3,2-a]pyrimidine-6-carboxylate
of ethyl 2-acetyl-3,7-dimethyl-5-(thiophen-2-yl)-5aDepartment of Studies in Chemistry, Central College Campus, Bangalore University, Bangalore 560 001, Karnataka, India
*Correspondence e-mail: noorsb@rediffmail.com
In the title compound, C17H18N2O3S2, the pyrimidine ring adopts a shallow sofa conformation, with the C atom bearing the axially-oriented thiophene ring as the flap [deviation = 0.439 (3) Å]. The plane of the thiophene ring lies almost normal to the pyrimidine ring, making a dihedral angle of 79.36 (19)°. In the crystal, pairs of very weak C—H⋯O hydrogen bonds link the molecules related by twofold rotation axes, forming R22(18) rings, which are in turn linked by another C—H⋯O interaction, forming chains of rings along [010]. In addition, weak C—H⋯π(thiophene) interactions link the chains into layers parallel to [001] and π–π interactions with a centroid–centroid distance of 3.772 (10) Å connect these layers into a three-dimensional network.
Keywords: crystal structure; fused pyrimidine derivative; hydrogen bonding; C—H⋯π interactions; π–π interactions.
CCDC reference: 1405373
1. Related literature
For the biological activities of fused pyrimidine derivatives, see: Atwal et al. (1991); Kappe et al. (1997); Singh et al. (2011); Ozair et al. (2010); Hayam et al. (2010). For related structures, see: Prasad et al. (2014); Nagarajaiah et al. (2012).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: SMART (Bruker,1998); cell SAINT-Plus (Bruker,1998); data reduction: SAINT-Plus; 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 CAMERON (Watkin et al., 1996); software used to prepare material for publication: WinGX (Farrugia, 2012).
Supporting information
CCDC reference: 1405373
10.1107/S2056989015010981/hb7433sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S2056989015010981/hb7433Isup2.hkl
Supporting information file. DOI: 10.1107/S2056989015010981/hb7433Isup3.cml
A mixture of 6-methyl-4-thiophen-2-yl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5- carboxylic acid ethyl ester (10 mmol) and 3-chloro-2,4-pentanedione (10 mmol) was refluxed in dry ethanol (20 mmol) for 12 h. The excess of solvent was distilled off and the solid hydrochloride salt that separated was collected by filtration, suspended in water and neutralized by aqueous sodium carbonate solution to yield the free base. The solution was filtered, the solid washed with water, dried and recrystallized from ethyl acetate to give the title compound (74% yield, mp 385 K). The compound was recrystallized by slow evaporation from 1:1 mixture of ethyl acetate and methanol, yielding pale- yellow blocks of the title compound.
The H atoms were placed at calculated positions in the riding-model approximation with C—H = 0.95 Å, 1.00 Å and 0.96 Å for aromatic, methyne and methyl H-atoms respectively, with Uiso(H) = 1.5Ueq(C) for methyl H atoms and Uiso(H) = 1.2Ueq(C) for other hydrogen atoms.
Data collection: SMART (Bruker,1998); cell
SAINT-Plus (Bruker,1998); data reduction: SAINT-Plus (Bruker,1998); 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 CAMERON (Watkin et al., 1996); software used to prepare material for publication: WinGX (Farrugia, 2012).Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. Unit-cell packing of the title compound showing C—H···O interactions as dotted lines. H atoms not involved in hydrogen bonding have been excluded. | |
Fig. 3. Unit-cell packing depicting the C—H···π and π–π interactions with dotted lines. |
C17H18N2O3S2 | F(000) = 760 |
Mr = 362.45 | Dx = 1.397 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3038 reflections |
a = 7.8835 (10) Å | θ = 2.6–25.0° |
b = 14.4041 (19) Å | µ = 0.33 mm−1 |
c = 15.231 (2) Å | T = 100 K |
β = 94.940 (4)° | Block, yellow |
V = 1723.2 (4) Å3 | 0.18 × 0.16 × 0.16 mm |
Z = 4 |
Bruker SMART APEX CCD diffractometer | 3038 independent reflections |
Radiation source: fine-focus sealed tube | 1984 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.046 |
ω scans | θmax = 25.0°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Bruker, 1998) | h = −9→9 |
Tmin = 0.944, Tmax = 0.950 | k = −17→17 |
12021 measured reflections | l = −17→18 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.065 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.189 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.1059P)2 + 1.4984P] where P = (Fo2 + 2Fc2)/3 |
3038 reflections | (Δ/σ)max < 0.001 |
221 parameters | Δρmax = 0.51 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
C17H18N2O3S2 | V = 1723.2 (4) Å3 |
Mr = 362.45 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.8835 (10) Å | µ = 0.33 mm−1 |
b = 14.4041 (19) Å | T = 100 K |
c = 15.231 (2) Å | 0.18 × 0.16 × 0.16 mm |
β = 94.940 (4)° |
Bruker SMART APEX CCD diffractometer | 3038 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1998) | 1984 reflections with I > 2σ(I) |
Tmin = 0.944, Tmax = 0.950 | Rint = 0.046 |
12021 measured reflections |
R[F2 > 2σ(F2)] = 0.065 | 0 restraints |
wR(F2) = 0.189 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.51 e Å−3 |
3038 reflections | Δρmin = −0.28 e Å−3 |
221 parameters |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | ||
S1 | 0.41155 (14) | 0.67664 (8) | 0.10428 (8) | 0.0478 (4) | |
S2 | 0.86975 (15) | 0.38590 (8) | 0.30180 (7) | 0.0514 (4) | |
N1 | 0.6122 (4) | 0.5389 (2) | 0.11268 (19) | 0.0343 (8) | |
C6 | 0.5337 (5) | 0.3792 (3) | 0.1355 (2) | 0.0384 (10) | |
O1 | 0.8379 (4) | 0.7993 (2) | 0.0552 (2) | 0.0610 (9) | |
C9 | 0.4445 (5) | 0.5583 (3) | 0.1190 (2) | 0.0378 (10) | |
N2 | 0.3249 (4) | 0.5002 (3) | 0.1340 (2) | 0.0472 (9) | |
C3 | 0.7148 (5) | 0.6131 (3) | 0.0965 (2) | 0.0345 (9) | |
C13 | 0.6889 (5) | 0.5373 (3) | 0.2994 (2) | 0.0378 (10) | |
H13 | 0.6144 | 0.5869 | 0.2815 | 0.045* | |
O2 | 0.4904 (5) | 0.2161 (2) | 0.1141 (3) | 0.0753 (11) | |
C2 | 0.6282 (5) | 0.6938 (3) | 0.0902 (3) | 0.0386 (10) | |
C16 | 0.5843 (6) | 0.2820 (3) | 0.1255 (3) | 0.0482 (11) | |
C17 | 0.9012 (5) | 0.5964 (3) | 0.0884 (3) | 0.0521 (12) | |
H17A | 0.9151 | 0.5420 | 0.0511 | 1.000* | |
H17B | 0.9592 | 0.5855 | 0.1470 | 1.000* | |
H17C | 0.9508 | 0.6509 | 0.0618 | 1.000* | |
C12 | 0.7368 (5) | 0.4638 (3) | 0.2456 (2) | 0.0359 (9) | |
C7 | 0.3696 (6) | 0.4072 (3) | 0.1363 (3) | 0.0434 (10) | |
C5 | 0.6754 (5) | 0.4494 (3) | 0.1488 (2) | 0.0359 (9) | |
H5 | 0.7734 | 0.4286 | 0.1162 | 0.043* | |
C10 | 0.8235 (8) | 0.1808 (3) | 0.1127 (4) | 0.0683 (15) | |
H10A | 0.7431 | 0.1448 | 0.0724 | 0.082* | |
H10B | 0.9319 | 0.1866 | 0.0849 | 0.082* | |
C14 | 0.7725 (6) | 0.5240 (3) | 0.3865 (3) | 0.0499 (11) | |
H14 | 0.7602 | 0.5662 | 0.4335 | 0.060* | |
C4 | 0.6955 (6) | 0.7881 (3) | 0.0792 (3) | 0.0447 (11) | |
C1 | 0.2188 (6) | 0.3437 (3) | 0.1387 (3) | 0.0592 (13) | |
H1A | 0.1198 | 0.3796 | 0.1538 | 1.000* | |
H1B | 0.2444 | 0.2954 | 0.1832 | 1.000* | |
H1C | 0.1940 | 0.3149 | 0.0808 | 1.000* | |
C8 | 0.5863 (7) | 0.8697 (3) | 0.0997 (4) | 0.0686 (15) | |
H8A | 0.5407 | 0.8599 | 0.1569 | 1.000* | |
H8B | 0.4920 | 0.8758 | 0.0538 | 1.000* | |
H8C | 0.6552 | 0.9264 | 0.1019 | 1.000* | |
C15 | 0.8682 (6) | 0.4481 (3) | 0.3959 (3) | 0.0484 (11) | |
H15 | 0.9293 | 0.4306 | 0.4499 | 0.058* | |
O3 | 0.7530 (4) | 0.2735 (2) | 0.1262 (2) | 0.0560 (8) | |
C11 | 0.8530 (10) | 0.1323 (5) | 0.1948 (4) | 0.110 (3) | |
H11A | 0.8940 | 0.0694 | 0.1839 | 0.166* | |
H11B | 0.7466 | 0.1286 | 0.2235 | 0.166* | |
H11C | 0.9387 | 0.1656 | 0.2332 | 0.166* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0422 (7) | 0.0400 (7) | 0.0619 (7) | 0.0079 (5) | 0.0093 (5) | 0.0074 (5) |
S2 | 0.0591 (8) | 0.0471 (7) | 0.0467 (7) | 0.0086 (5) | −0.0026 (5) | 0.0011 (5) |
N1 | 0.0349 (19) | 0.0318 (18) | 0.0364 (18) | 0.0033 (15) | 0.0036 (14) | 0.0039 (14) |
C6 | 0.043 (2) | 0.038 (2) | 0.033 (2) | −0.0054 (19) | −0.0006 (17) | −0.0010 (17) |
O1 | 0.061 (2) | 0.047 (2) | 0.075 (2) | −0.0107 (16) | 0.0111 (18) | 0.0040 (16) |
C9 | 0.037 (2) | 0.039 (2) | 0.037 (2) | 0.0067 (19) | 0.0031 (17) | 0.0017 (18) |
N2 | 0.038 (2) | 0.048 (2) | 0.057 (2) | −0.0058 (18) | 0.0122 (17) | −0.0046 (18) |
C3 | 0.038 (2) | 0.036 (2) | 0.029 (2) | −0.0036 (19) | 0.0006 (16) | 0.0010 (16) |
C13 | 0.048 (2) | 0.035 (2) | 0.030 (2) | −0.0105 (18) | −0.0020 (18) | −0.0038 (17) |
O2 | 0.077 (3) | 0.041 (2) | 0.106 (3) | −0.0134 (19) | −0.006 (2) | −0.0007 (19) |
C2 | 0.041 (2) | 0.036 (2) | 0.039 (2) | −0.0001 (18) | 0.0054 (18) | 0.0045 (18) |
C16 | 0.062 (3) | 0.036 (2) | 0.045 (3) | −0.009 (2) | −0.005 (2) | −0.0013 (19) |
C17 | 0.036 (2) | 0.051 (3) | 0.070 (3) | 0.001 (2) | 0.008 (2) | 0.008 (2) |
C12 | 0.036 (2) | 0.031 (2) | 0.040 (2) | 0.0005 (17) | 0.0011 (17) | 0.0016 (17) |
C7 | 0.051 (3) | 0.039 (3) | 0.041 (2) | −0.006 (2) | 0.0069 (19) | 0.0014 (18) |
C5 | 0.042 (2) | 0.032 (2) | 0.034 (2) | 0.0055 (18) | 0.0034 (17) | −0.0009 (16) |
C10 | 0.085 (4) | 0.042 (3) | 0.078 (4) | 0.013 (3) | 0.008 (3) | −0.014 (3) |
C14 | 0.057 (3) | 0.051 (3) | 0.042 (2) | 0.000 (2) | 0.004 (2) | −0.009 (2) |
C4 | 0.055 (3) | 0.040 (2) | 0.039 (2) | −0.004 (2) | 0.003 (2) | 0.0020 (19) |
C1 | 0.051 (3) | 0.057 (3) | 0.070 (3) | −0.022 (2) | 0.013 (2) | 0.001 (2) |
C8 | 0.087 (4) | 0.038 (3) | 0.083 (4) | 0.008 (3) | 0.019 (3) | −0.005 (2) |
C15 | 0.052 (3) | 0.054 (3) | 0.038 (2) | −0.001 (2) | −0.0011 (19) | 0.003 (2) |
O3 | 0.060 (2) | 0.0390 (18) | 0.067 (2) | 0.0087 (15) | −0.0048 (16) | −0.0080 (15) |
C11 | 0.157 (7) | 0.091 (5) | 0.086 (5) | 0.063 (5) | 0.027 (4) | 0.017 (4) |
S1—C9 | 1.736 (4) | C17—H17B | 0.9902 |
S1—C2 | 1.757 (4) | C17—H17C | 0.9902 |
S2—C15 | 1.692 (4) | C12—C5 | 1.525 (5) |
S2—C12 | 1.714 (4) | C7—C1 | 1.502 (6) |
N1—C9 | 1.363 (5) | C5—H5 | 1.0000 |
N1—C3 | 1.375 (5) | C10—C11 | 1.433 (7) |
N1—C5 | 1.471 (5) | C10—O3 | 1.467 (5) |
C6—C7 | 1.355 (6) | C10—H10A | 0.9900 |
C6—C16 | 1.468 (6) | C10—H10B | 0.9900 |
C6—C5 | 1.508 (6) | C14—C15 | 1.328 (6) |
O1—C4 | 1.221 (5) | C14—H14 | 0.9500 |
C9—N2 | 1.296 (5) | C4—C8 | 1.506 (6) |
N2—C7 | 1.385 (5) | C1—H1A | 0.9828 |
C3—C2 | 1.348 (5) | C1—H1B | 0.9828 |
C3—C17 | 1.505 (6) | C1—H1C | 0.9828 |
C13—C12 | 1.410 (5) | C8—H8A | 0.9913 |
C13—C14 | 1.442 (6) | C8—H8B | 0.9913 |
C13—H13 | 0.9500 | C8—H8C | 0.9913 |
O2—C16 | 1.207 (5) | C15—H15 | 0.9500 |
C2—C4 | 1.472 (6) | C11—H11A | 0.9800 |
C16—O3 | 1.335 (5) | C11—H11B | 0.9800 |
C17—H17A | 0.9902 | C11—H11C | 0.9800 |
C9—S1—C2 | 91.04 (19) | C6—C5—C12 | 113.0 (3) |
C15—S2—C12 | 91.6 (2) | N1—C5—H5 | 109.1 |
C9—N1—C3 | 116.3 (3) | C6—C5—H5 | 109.1 |
C9—N1—C5 | 116.9 (3) | C12—C5—H5 | 109.1 |
C3—N1—C5 | 124.2 (3) | C11—C10—O3 | 110.9 (4) |
C7—C6—C16 | 123.5 (4) | C11—C10—H10A | 109.5 |
C7—C6—C5 | 119.8 (4) | O3—C10—H10A | 109.5 |
C16—C6—C5 | 116.7 (4) | C11—C10—H10B | 109.4 |
N2—C9—N1 | 127.2 (4) | O3—C10—H10B | 109.5 |
N2—C9—S1 | 123.7 (3) | H10A—C10—H10B | 108.0 |
N1—C9—S1 | 109.1 (3) | C15—C14—C13 | 114.8 (4) |
C9—N2—C7 | 116.2 (4) | C15—C14—H14 | 122.6 |
C2—C3—N1 | 112.4 (3) | C13—C14—H14 | 122.6 |
C2—C3—C17 | 128.6 (4) | O1—C4—C2 | 120.4 (4) |
N1—C3—C17 | 119.0 (3) | O1—C4—C8 | 121.0 (4) |
C12—C13—C14 | 108.1 (4) | C2—C4—C8 | 118.6 (4) |
C12—C13—H13 | 126.0 | C7—C1—H1A | 109.8 |
C14—C13—H13 | 125.9 | C7—C1—H1B | 109.7 |
C3—C2—C4 | 128.2 (4) | H1A—C1—H1B | 109.2 |
C3—C2—S1 | 111.2 (3) | C7—C1—H1C | 109.8 |
C4—C2—S1 | 120.5 (3) | H1A—C1—H1C | 109.2 |
O2—C16—O3 | 121.8 (4) | H1B—C1—H1C | 109.2 |
O2—C16—C6 | 126.6 (5) | C4—C8—H8A | 110.6 |
O3—C16—C6 | 111.5 (4) | C4—C8—H8B | 110.6 |
C3—C17—H17A | 110.5 | H8A—C8—H8B | 108.3 |
C3—C17—H17B | 110.5 | C4—C8—H8C | 110.6 |
H17A—C17—H17B | 108.4 | H8A—C8—H8C | 108.3 |
C3—C17—H17C | 110.5 | H8B—C8—H8C | 108.3 |
H17A—C17—H17C | 108.4 | C14—C15—S2 | 112.9 (3) |
H17B—C17—H17C | 108.4 | C14—C15—H15 | 123.5 |
C13—C12—C5 | 125.8 (3) | S2—C15—H15 | 123.5 |
C13—C12—S2 | 112.6 (3) | C16—O3—C10 | 118.1 (4) |
C5—C12—S2 | 121.6 (3) | C10—C11—H11A | 109.5 |
C6—C7—N2 | 121.9 (4) | C10—C11—H11B | 109.5 |
C6—C7—C1 | 125.3 (4) | H11A—C11—H11B | 109.5 |
N2—C7—C1 | 112.8 (4) | C10—C11—H11C | 109.5 |
N1—C5—C6 | 108.3 (3) | H11A—C11—H11C | 109.5 |
N1—C5—C12 | 108.2 (3) | H11B—C11—H11C | 109.5 |
C3—N1—C9—N2 | −179.9 (4) | C5—C6—C7—N2 | 11.1 (6) |
C5—N1—C9—N2 | −17.4 (6) | C16—C6—C7—C1 | 8.2 (6) |
C3—N1—C9—S1 | −0.2 (4) | C5—C6—C7—C1 | −169.4 (4) |
C5—N1—C9—S1 | 162.2 (2) | C9—N2—C7—C6 | 9.1 (6) |
C2—S1—C9—N2 | 179.7 (4) | C9—N2—C7—C1 | −170.4 (4) |
C2—S1—C9—N1 | 0.0 (3) | C9—N1—C5—C6 | 33.4 (4) |
N1—C9—N2—C7 | −6.0 (6) | C3—N1—C5—C6 | −165.7 (3) |
S1—C9—N2—C7 | 174.4 (3) | C9—N1—C5—C12 | −89.4 (4) |
C9—N1—C3—C2 | 0.4 (5) | C3—N1—C5—C12 | 71.5 (4) |
C5—N1—C3—C2 | −160.6 (3) | C7—C6—C5—N1 | −31.2 (5) |
C9—N1—C3—C17 | −179.8 (3) | C16—C6—C5—N1 | 151.0 (3) |
C5—N1—C3—C17 | 19.2 (5) | C7—C6—C5—C12 | 88.6 (4) |
N1—C3—C2—C4 | 175.6 (4) | C16—C6—C5—C12 | −89.2 (4) |
C17—C3—C2—C4 | −4.2 (7) | C13—C12—C5—N1 | 20.6 (5) |
N1—C3—C2—S1 | −0.4 (4) | S2—C12—C5—N1 | −162.0 (3) |
C17—C3—C2—S1 | 179.8 (3) | C13—C12—C5—C6 | −99.3 (4) |
C9—S1—C2—C3 | 0.2 (3) | S2—C12—C5—C6 | 78.1 (4) |
C9—S1—C2—C4 | −176.1 (3) | C12—C13—C14—C15 | −1.3 (5) |
C7—C6—C16—O2 | 2.5 (7) | C3—C2—C4—O1 | 16.3 (7) |
C5—C6—C16—O2 | −179.8 (4) | S1—C2—C4—O1 | −168.1 (3) |
C7—C6—C16—O3 | 179.4 (4) | C3—C2—C4—C8 | −162.5 (4) |
C5—C6—C16—O3 | −2.8 (5) | S1—C2—C4—C8 | 13.1 (5) |
C14—C13—C12—C5 | 178.8 (4) | C13—C14—C15—S2 | 0.7 (5) |
C14—C13—C12—S2 | 1.3 (4) | C12—S2—C15—C14 | 0.1 (4) |
C15—S2—C12—C13 | −0.8 (3) | O2—C16—O3—C10 | −0.2 (6) |
C15—S2—C12—C5 | −178.5 (3) | C6—C16—O3—C10 | −177.3 (3) |
C16—C6—C7—N2 | −171.2 (4) | C11—C10—O3—C16 | −87.9 (6) |
Cg1 is the centroid of the S2/C12–C15 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1C···O1i | 0.98 | 2.64 | 3.598 (6) | 166 |
C13—H13···O2ii | 0.95 | 2.63 | 3.269 (8) | 125 |
C11—H11A···Cg1iii | 0.98 | 2.89 | 3.693 (2) | 139 |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+1, y+1/2, −z+1/2; (iii) −x, −y+1, −z. |
Cg1 is the centroid of the S2/C12–C15 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1C···O1i | 0.98 | 2.64 | 3.598 (6) | 166 |
C13—H13···O2ii | 0.95 | 2.63 | 3.269 (8) | 125 |
C11—H11A···Cg1iii | 0.98 | 2.89 | 3.693 (2) | 139 |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+1, y+1/2, −z+1/2; (iii) −x, −y+1, −z. |
Acknowledgements
NLP is thankful to the University Grants Commission (UGC), India for the UGC–JRF and MSK thanks the UGC for the UGC–BSR Meritorious Fellowship.
References
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Pyrimidine derivatives are important class of compounds which display number of pharmacological properties including antiviral, antitumour, antibacterial and antihypertensive effects (Atwal et al., 1991; Kappe et al., 1997). Pyrimidine has been subjected to a large variety of structural modifications in order to synthesize derivatives (Singh et al., 2011) with different biological properties, among which, thiazole ring fused to pyrimidine ring resulting in thiazolopyrimidine is found to be more active (Ozair et al., 2010; Hayam et al., 2010). Herein, we report the crystal structure of the title compound (1). The bond lengths and angles in the title compound are in good agreement with the corresponding bond distances and angles reported in closely related structures (Nagarajaiah et al., 2012; Prasad et al., 2014). The molecular structure of the compound C17H18N2O3S2 is shown in Fig. 1. The thiophenyl ring at chiral carbon C5 is positioned axially and exactly bisects the pyrimidine ring with a dihedral angle of 82.973 (1)°. The thiazine and pyrimidine ring form a dihedral angle of 5.975 (1)°. In the central pyrimidine ring, the chiral carbon atom C6 is displaced by 0.3130 (4) Å and adopts a flattened sofa conformation. The exocyclic ester group at C6 adopts cis orientation with respect to C6=C7 double bond and the carboxyl group (C11/C10/O3/C16) is slightly deviating from the thiozolopyrimidine plane at -87.946 (6)°. The crystal structure is mainly stabilized by a variety of intermolecular C—H···O interactions. C1—H1C···O1 hydrogen bonds link the molecules related by twofold rotation axes, forming R22(18) loops, which are in turn linked by C13—H13···O2 interactions to form chains of rings along [010] (Table.1; Fig. 2). In addition, weak C—H···π (thiophene) interactions of the type C11—H11A···Cg link the chains into layers parallel to [001] and π–π interactions between inversion-related thiazolopyrimidine rings with a centroid—centroid distance of 3.772 (10) Å connect these layers into a three-dimensional network (Fig. 3).