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ISSN: 2414-3146

5-Acetyl-6-methyl-4-phenyl-1-(prop-2-yn­yl)-3,4-di­hydro­pyrimidin-2(1H)-one

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aLaboratoire de Chimie Bio-organique et Macromoléculaire, Faculté des Sciences et Techniques Guéliz, Marrakech, Morocco, bLaboratoire de Chimie Biomoléculaire et Médicinale, Faculté des Sciences Semlalia, Marrakech, Morocco, cLaboratoire de la Matière Condensée et des Nanostructures, Faculté des Sciences et Techniques Guéliz, Marrakech, Morocco, and dLaboratoire de Chimie Appliquée des Matériaux, Centres des Sciences des Matériaux, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: h_kaoukabi@yahoo.com

Edited by C. Rizzoli, Universita degli Studi di Parma, Italy (Received 4 December 2017; accepted 18 December 2017; online 19 December 2017)

The 4-di­hydro­pyrimidin-2(1H)-one moiety of the title mol­ecule, C16H16N2O2, displays a half-chair conformation. The least-squares mean plane through this heterocycle is almost perpendicular to the aromatic ring [dihedral angle = 89.52 (8)°] and to the prop-2-ynyl chain [C—C—N—C torsion angle of −73.2 (2)°]. The mean plane through the acetyl group makes a dihedral angle of 30.93 (10)° with the mean plane of the heterocycle. There is an intra­molecular C—H⋯O hydrogen bond forming an S(6) ring motif. In the crystal, mol­ecules are linked by pairs of N—H⋯O hydrogen bonds forming inversion dimers.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

In past decades, di­hydro­pyrimidino­nes (DHPMs) and their derivatives have attracted considerable inter­est due to their heterocyclic scaffold and inter­esting pharmacological properties such as anti­viral, anti­tumor, anti inflammatory as well their applications as calcium channel blockers and anti­cancer drugs (Ali et al., 2016[Ali, F., Khan, K. M., Salar, U., Iqbal, S., Taha, M., Ismail, N. H., Perveen, S., Wadood, A., Ghufran, M. & Ali, B. (2016). Bioorg. Med. Chem. 24, 3624-3635.]; Desai et al., 2016[Desai, N. C., Trivedi, A. R. & Khedkar, V. M. (2016). Bioorg. Med. Chem. Lett. 26, 4030-4035.]; Xue et al., 2016[Xue, H., Zhao, Y., Wu, H., Wang, Z., Yang, B., Wei, Y., Wang, Z. & Tao, L. (2016). J. Am. Chem. Soc. 138, 8690-8693.]; Dalil et al., 2016[Dalil, S. Z. H., Shirini, F. & Shojaei, A. F. (2016). RSC Adv. 6, 67072-67085.]; Dhumaskar et al., 2014[Dhumaskar, K. L., Meena, S. N., Ghadi, S. C. & Tilve, S. G. (2014). Bioorg. Med. Chem. Lett. 24, 2897-2899.]; Jetti et al., 2014[Jetti, S. R., Upadhyaya, A. & Jain, S. (2014). Med. Chem. Res. 23, 4356-4366.]). Different strategies have been used for the modification of 3,4-di­hydro­pyrimidine-2(1H)-ones. For instance, N-alkyl­ation is one of the most usable but other methods include mild base Cs2CO3, K2CO3 (Putatunda et al., 2012[Putatunda, S., Chakraborty, S., Ghosh, S., Nandi, P., Chakraborty, S., Sen, P. C. & Chakraborty, A. (2012). Eur. J. Med. Chem. 54, 223-231.]), the Mitsunobu-type reaction (Dallinger & Kappe, 2002[Dallinger, D. & Kappe, C. O. (2002). Synlett, pp. 1901-1903.]), or phase-transfer catalysis (Singh et al., 2009[Singh, K., Arora, D., Poremsky, E., Lowery, J. & Moreland, R. S. (2009). Eur. J. Med. Chem. 44, 1997-2001.]). Unfortunately, these strategies suffer from the disadvantage that the procedures need to be carried out in harsh conditions. In this article, we present a convenient approach for the preparation of an N1-alkyl­ated DHPM derivative as a major product using potassium t-butoxide in DMF at room temperature.

The mol­ecule of the title compound is built up from a 3,4-di­hydro­pyrimidin-2(1H)-one ring linked to an acetyl group, one prop-2-ynyl chain and to methyl and phenyl groups as shown in Fig. 1[link]. The di­hydro­pyrimidine ring adopts a half-chair conformation as indicated by the total puckering amplitude Q2 = 0.3602 (15) Å, and spherical polar angle θ = 106.8 (2)° with φ2 = 10.5 (2)°. The dihedral angle between the mean plane passing through the heterocycle and that through the aromatic ring is 89.52 (8)°. The prop-2-ynyl chain is nearly perpendicular to the mean plane of the di­hydro­pyrimidine ring, as indicated by the C9—C8—N1—C4 torsion angle of −73.2 (2)°. The mol­ecular conformation is stabilized by an intra­molecular C—H⋯O hydrogen bond (Table 1[link]), forming an S(6) ring motif. In the crystal, mol­ecules are linked together by pairs of N—H⋯O hydrogen bonds, forming inversion dimers (Fig. 2[link], Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C7—H7C⋯O1 0.96 2.21 2.862 (3) 125
N2—H2⋯O2i 0.86 2.02 2.8612 (17) 164
Symmetry code: (i) -x+1, -y+1, -z+1.
[Figure 1]
Figure 1
The mol­ecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. The intra­molecular hydrogen bond is shown as a dashed line.
[Figure 2]
Figure 2
Crystal packing of the title compound, showing mol­ecules linked through N—H⋯O hydrogen bonds (dotted lines).

Synthesis and crystallization

The title compound was prepared in good yield (70%) through condensation of 5-acetyl-6-methyl-4-phenyl-3,4-di­hydro­pyrimidin-2(1H)-one (1 g, 4.34 mmol) with propargyl bromide (0.73 ml, 9.55 mmol) in the presence of potassium t-butoxide as a base in N,N-di­methyl­formamide (DMF, 10 ml) at room temperature for one h. After completion of the reaction (TLC), the product was extracted with ethyl acetate and washed with water (2 × 20 ml), the organic layer separated and dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The resulting crude product was purified by a column packed with silica gel. The obtained product was crystallized by slow evaporation of n-hexa­ne/ethyl acetate (7:3 v/v) mixture, m.p. 424 K.

The confirmation of the synthesized compound was performed by spectroscopic techniques. The compound showed signals in its 1H NMR spectrum (DMSO-d6) δ = 2.09 (s, 3H, CH3CO), 2.53 (s, 3H, CH3), 3.26 (s, 1H, CH), 4.39–4.62 (m, 2H, –CH2–), 5.22 (s, 1H, H-4), 7.27–7.32 (m, 5H, CAr), 8.13 (s, 1H, N3—H). The 13C NMR (DMSO-d6) spectrum signals appeared at: δ = 196.06 (CO), 151.92 (C-6), 147.32 (C-2), 142.99 (C-1′), 128.64 (C-4′), 128.64, 127.66 and 126.49 (other aromatic carbons), 113.23 (C-5), 80.31 (C-alkyne), 74.27 (CH-alkyne), 53.00 (C-4), 31.69 (–CH2–), 30.30 (CH3 at C-4′), 16.05 (CH3 at C-6). Further, ESI–MS [M + H]+ mass spectrum showed the [M+1] ion peak at m/z 269.3, which is in agreement with the mol­ecular formula C16H16N2O2. The IR spectrum of the compound showed an absorption band at 3301–3229 cm−1 indicating the presence of Csp—H stretching. A strong absorption band at 3094 cm−1 was attributed to the N–H stretching, and absorption bands at 2121, 1665, 1209 cm−1 indicated the presence of C≡C, C=O and CN. UV/Vis (MeOH): λmax = 300 and 222 nm.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Two outliers (200, 110) were omitted in the last cycles of refinement.

Table 2
Experimental details

Crystal data
Chemical formula C16H16N2O2
Mr 268.31
Crystal system, space group Monoclinic, C2/c
Temperature (K) 296
a, b, c (Å) 22.656 (2), 12.2607 (12), 10.2189 (10)
β (°) 100.363 (4)
V3) 2792.3 (5)
Z 8
Radiation type Mo Kα
μ (mm−1) 0.09
Crystal size (mm) 0.36 × 0.28 × 0.22
 
Data collection
Diffractometer Bruker X8 APEX
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.645, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections 38459, 3614, 2502
Rint 0.047
(sin θ/λ)max−1) 0.676
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.133, 1.02
No. of reflections 3614
No. of parameters 184
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.26, −0.23
Computer programs: APEX2 and SAINT (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2008) and publCIF (Westrip, 2010).

5-Acetyl-6-methyl-4-phenyl-1-(prop-2-ynyl)-3,4-dihydropyrimidin-2(1H)-one top
Crystal data top
C16H16N2O2Dx = 1.276 Mg m3
Mr = 268.31Melting point: 424 K
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 22.656 (2) ÅCell parameters from 3614 reflections
b = 12.2607 (12) Åθ = 2.7–28.7°
c = 10.2189 (10) ŵ = 0.09 mm1
β = 100.363 (4)°T = 296 K
V = 2792.3 (5) Å3Prism, colourless
Z = 80.36 × 0.28 × 0.22 mm
F(000) = 1136
Data collection top
Bruker X8 APEX
diffractometer
3614 independent reflections
Radiation source: fine-focus sealed tube2502 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.047
φ and ω scansθmax = 28.7°, θmin = 2.7°
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
h = 3030
Tmin = 0.645, Tmax = 0.747k = 1616
38459 measured reflectionsl = 1311
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.046 w = 1/[σ2(Fo2) + (0.053P)2 + 1.4276P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.133(Δ/σ)max < 0.001
S = 1.02Δρmax = 0.26 e Å3
3614 reflectionsΔρmin = 0.23 e Å3
184 parametersExtinction correction: SHELXL2014 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0026 (5)
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. All H atoms were placed geometrically and isotropically refined with C–H = 0.93–0.98 Å, N–H = 0.86 Å, and with Uiso(H) = 1.2 Ueq(C, N) or 1.5 Ueq(C) for methyl H atoms. A rotating model was used for the methyl groups.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.37406 (10)0.29201 (18)0.92689 (19)0.0762 (6)
H1A0.36220.24940.99660.114*
H1B0.33920.32470.87400.114*
H1C0.40130.34820.96510.114*
C20.40429 (7)0.21998 (14)0.84101 (16)0.0561 (4)
C30.41421 (6)0.26245 (11)0.71114 (14)0.0431 (3)
C40.42533 (6)0.19789 (12)0.61119 (15)0.0457 (3)
C50.45892 (6)0.35303 (12)0.49448 (16)0.0479 (4)
C60.41194 (6)0.38466 (11)0.69024 (14)0.0416 (3)
H60.42740.41890.77620.050*
C70.42452 (8)0.07574 (13)0.6116 (2)0.0642 (5)
H7A0.46470.04870.61870.096*
H7B0.40050.04990.53040.096*
H7C0.40780.05030.68590.096*
C80.43732 (9)0.18379 (16)0.37151 (19)0.0668 (5)
H8A0.45760.22490.31160.080*
H8B0.45860.11540.39150.080*
C90.37589 (10)0.16135 (14)0.30636 (17)0.0616 (5)
C100.32600 (12)0.14343 (18)0.2591 (2)0.0814 (6)
H100.28630.12920.22150.098*
C110.34962 (6)0.43142 (11)0.64005 (14)0.0416 (3)
C120.33358 (8)0.52996 (13)0.68949 (18)0.0598 (4)
H120.36060.56570.75470.072*
C130.27831 (9)0.57605 (15)0.6439 (2)0.0710 (5)
H130.26820.64190.67930.085*
C140.23830 (8)0.52553 (16)0.54682 (19)0.0661 (5)
H140.20100.55690.51590.079*
C150.25341 (8)0.42845 (17)0.49538 (18)0.0654 (5)
H150.22640.39420.42880.078*
C160.30871 (7)0.38075 (14)0.54179 (16)0.0540 (4)
H160.31840.31440.50680.065*
N10.43908 (6)0.24585 (10)0.49518 (13)0.0492 (3)
N20.45282 (5)0.41268 (10)0.60009 (13)0.0475 (3)
H20.47410.47090.61610.057*
O10.42141 (8)0.12989 (12)0.88272 (15)0.0905 (5)
O20.48212 (6)0.38750 (10)0.40209 (12)0.0675 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0941 (14)0.0835 (14)0.0571 (11)0.0056 (11)0.0301 (10)0.0089 (10)
C20.0586 (9)0.0570 (9)0.0511 (9)0.0103 (7)0.0057 (7)0.0122 (7)
C30.0382 (7)0.0428 (7)0.0473 (8)0.0046 (5)0.0048 (6)0.0070 (6)
C40.0380 (7)0.0426 (7)0.0560 (9)0.0023 (6)0.0071 (6)0.0068 (6)
C50.0386 (7)0.0504 (8)0.0552 (9)0.0059 (6)0.0101 (6)0.0078 (7)
C60.0413 (7)0.0419 (7)0.0404 (7)0.0077 (5)0.0039 (6)0.0016 (6)
C70.0699 (11)0.0420 (8)0.0797 (12)0.0004 (8)0.0107 (9)0.0044 (8)
C80.0777 (12)0.0605 (10)0.0713 (11)0.0010 (9)0.0380 (10)0.0101 (9)
C90.0905 (14)0.0508 (9)0.0465 (9)0.0035 (9)0.0206 (9)0.0069 (7)
C100.1027 (17)0.0762 (14)0.0599 (12)0.0077 (12)0.0005 (11)0.0086 (10)
C110.0432 (7)0.0411 (7)0.0405 (7)0.0043 (6)0.0077 (6)0.0031 (6)
C120.0630 (10)0.0492 (9)0.0643 (10)0.0009 (7)0.0040 (8)0.0085 (8)
C130.0704 (12)0.0539 (10)0.0884 (14)0.0140 (9)0.0133 (10)0.0021 (10)
C140.0553 (10)0.0698 (12)0.0730 (12)0.0148 (8)0.0107 (9)0.0146 (9)
C150.0486 (9)0.0828 (13)0.0600 (10)0.0009 (8)0.0028 (8)0.0049 (9)
C160.0482 (8)0.0573 (9)0.0546 (9)0.0004 (7)0.0039 (7)0.0107 (7)
N10.0504 (7)0.0467 (7)0.0537 (7)0.0039 (5)0.0180 (6)0.0010 (6)
N20.0425 (6)0.0443 (6)0.0556 (8)0.0130 (5)0.0087 (5)0.0035 (6)
O10.1257 (13)0.0719 (9)0.0762 (9)0.0121 (8)0.0239 (9)0.0339 (8)
O20.0714 (8)0.0715 (8)0.0659 (7)0.0185 (6)0.0294 (6)0.0075 (6)
Geometric parameters (Å, º) top
C1—C21.495 (3)C8—C91.457 (3)
C1—H1A0.9600C8—N11.470 (2)
C1—H1B0.9600C8—H8A0.9700
C1—H1C0.9600C8—H8B0.9700
C2—O11.222 (2)C9—C101.167 (3)
C2—C31.480 (2)C10—H100.9300
C3—C41.351 (2)C11—C121.383 (2)
C3—C61.5131 (19)C11—C161.385 (2)
C4—N11.4075 (19)C12—C131.377 (2)
C4—C71.498 (2)C12—H120.9300
C5—O21.2349 (18)C13—C141.366 (3)
C5—N21.331 (2)C13—H130.9300
C5—N11.3892 (19)C14—C151.369 (3)
C6—N21.4600 (17)C14—H140.9300
C6—C111.5248 (19)C15—C161.387 (2)
C6—H60.9800C15—H150.9300
C7—H7A0.9600C16—H160.9300
C7—H7B0.9600N2—H20.8600
C7—H7C0.9600
C2—C1—H1A109.5C9—C8—H8A109.3
C2—C1—H1B109.5N1—C8—H8A109.3
H1A—C1—H1B109.5C9—C8—H8B109.3
C2—C1—H1C109.5N1—C8—H8B109.3
H1A—C1—H1C109.5H8A—C8—H8B108.0
H1B—C1—H1C109.5C10—C9—C8177.27 (19)
O1—C2—C3122.76 (17)C9—C10—H10180.0
O1—C2—C1118.65 (16)C12—C11—C16118.11 (14)
C3—C2—C1118.55 (15)C12—C11—C6119.59 (13)
C4—C3—C2123.42 (14)C16—C11—C6122.25 (13)
C4—C3—C6118.66 (13)C13—C12—C11121.18 (16)
C2—C3—C6117.92 (13)C13—C12—H12119.4
C3—C4—N1119.44 (13)C11—C12—H12119.4
C3—C4—C7125.43 (14)C14—C13—C12120.28 (17)
N1—C4—C7115.12 (14)C14—C13—H13119.9
O2—C5—N2123.52 (14)C12—C13—H13119.9
O2—C5—N1120.68 (15)C13—C14—C15119.60 (17)
N2—C5—N1115.77 (13)C13—C14—H14120.2
N2—C6—C3108.24 (11)C15—C14—H14120.2
N2—C6—C11110.69 (11)C14—C15—C16120.55 (17)
C3—C6—C11115.19 (11)C14—C15—H15119.7
N2—C6—H6107.5C16—C15—H15119.7
C3—C6—H6107.5C11—C16—C15120.29 (16)
C11—C6—H6107.5C11—C16—H16119.9
C4—C7—H7A109.5C15—C16—H16119.9
C4—C7—H7B109.5C5—N1—C4121.35 (13)
H7A—C7—H7B109.5C5—N1—C8116.37 (13)
C4—C7—H7C109.5C4—N1—C8122.15 (13)
H7A—C7—H7C109.5C5—N2—C6123.52 (12)
H7B—C7—H7C109.5C5—N2—H2118.2
C9—C8—N1111.51 (13)C6—N2—H2118.2
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C7—H7C···O10.962.212.862 (3)125
N2—H2···O2i0.862.022.8612 (17)164
Symmetry code: (i) x+1, y+1, z+1.
 

Acknowledgements

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

References

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