Ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

M Nizam Mohideen; A Rasheeth; C A M A Huq; S Syed Nizar

doi:10.1107/S1600536808025610

. 2008 Aug 13;64(Pt 9):o1752. doi: 10.1107/S1600536808025610

Ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate

M Nizam Mohideen ^a,^*, A Rasheeth ^b, C A M A Huq ^b, S Syed Nizar ^b

PMCID: PMC2960668 PMID: 21201734

Abstract

The title compound, C₁₄H₁₆N₂O₃, belongs to a group of esters of 2-oxo- and 1,2,3,4-tetrahydropyrimidine-5-carboxylic acids, which exhibit a wide spectrum of biological activities. The dihydropyrimidine ring adopts a screw-boat conformation. The crystal packing is stabilized by strong N—H⋯O and weak C—H⋯O intermolecular hydrogen bonds. An intramolecular C—H⋯O hydrogen bond is also present.

Related literature

For related literature, see: Atwal et al. (1991 ▶); Broughton et al. (1975 ▶); Cremer & Pople (1975 ▶); Kappe et al. (1997 ▶); Li et al. (2005 ▶); Nardelli (1983 ▶); Overman et al. (1995 ▶).

Experimental

Crystal data

C₁₄H₁₆N₂O₃
M _r = 260.29
Triclinic,
a = 7.5495 (2) Å
b = 8.9797 (3) Å
c = 11.0812 (3) Å
α = 107.843 (2)°
β = 108.603 (1)°
γ = 98.244 (2)°
V = 653.07 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 (2) K
0.3 × 0.2 × 0.2 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: none
16135 measured reflections
3710 independent reflections
2972 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.159
S = 1.00
3710 reflections
174 parameters
H-atom parameters constrained
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); 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, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808025610/bt2758sup1.cif

e-64-o1752-sup1.cif^{(18.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808025610/bt2758Isup2.hkl

e-64-o1752-Isup2.hkl^{(178.2KB, 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—H1⋯O2ⁱ	0.86	2.37	3.1773 (13)	156
N2—H2⋯O1ⁱⁱ	0.86	2.00	2.8568 (13)	178
C11—H11A⋯O1ⁱⁱⁱ	0.96	2.58	3.1785 (16)	121
C11—H11C⋯O2	0.96	2.44	2.8379 (17)	105

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

Acknowledgments

MNM, AR, CAMAH and SSN thank the management of The New College, Chennai, India, for providing the necessary facilities.

supplementary crystallographic information

Comment

The title compound belongs to the group of esters of 2-oxo and -1,2,3,4-tetrahydropyrimidine-5-carboxylic acids, which are known as `Biginelli compounds' (Kappe et al., 1997). It has been suggested that the substituent effect may be attributable to intramolecular hydrogen bonding between the alkoxy oxygen and the proton of the pyrimidine ring NH group (Broughton et al., 1975). Several marine alkaloids having the dihydropyrimidine core unit have been found to show interesting biological activities, such as antiviral, antibacterial and anti-inflammatory (Overman et al., 1995). Many functionalized derivatives are used as calcium channel blockers and antihypertensive agents (Atwal et al., 1991). Against this background and in order to obtain detailed information on its molecular conformation, the structure of the title compound has been determined and the results are presented here.

The bond lengths and angles are comparable with the similar structure reported in the literature (Li et al., 2005). The six membered ring (atoms N1, N2, C7, C8, C9, C10) of the dihydropyrimidine group adopts a screw boat conformation; the puckering parameters are q₂ = 0.257 (1) Å and φ = 211.7 (2)° (Cremer & Pople, 1975), and the lowest displacement asymmetry parameters Δ_S(N1) is 14.4 (1)° (Nardelli, 1983), with atom O1 deviating by -0.116 (1) Å from the least squares plane of the ring.

The dihedral angle between the pyrimidine and benzene rings is 86.5 (1)°, close to the value of 82.8 (6)° found in ethyl 4-(4-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5- carboxylate.

The crystal packing is stabilized by strong N—H···O and C—H···O intermolecular hydrogen bonds (Table 1).

Experimental

A mixture of benzaldehyde (0.106 g, 1 mmol), ethyl acetoacetate (0.130 g, 1 mmol) and urea (0.070 g, 1.17 mmol) was ground with four drops of ortho phosphoric acid for about 30 minutes. The reaction mixture was cooled for 15 minutes and poured into a beaker containing 50 ml of cold water. The precipitate obtained was filtered, washed with water and ethanol to get white solid. Single crystals of the title compound suitable for X-ray diffraction were obtained by slow evaporation of a solution in ethanol (0.26 g, 92% yield; mp 203–204).