Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807046752/hb2552sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807046752/hb2552Isup2.hkl |
CCDC reference: 664215
Key indicators
- Single-crystal X-ray study
- T = 294 K
- Mean (C-C) = 0.004 Å
- R factor = 0.040
- wR factor = 0.107
- Data-to-parameter ratio = 12.8
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ? PLAT154_ALERT_1_C The su's on the Cell Angles are Equal (x 10000) 400 Deg. PLAT222_ALERT_3_C Large Non-Solvent H Ueq(max)/Ueq(min) ... 3.11 Ratio
Alert level G PLAT793_ALERT_1_G Check the Absolute Configuration of C4 = ... S PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 2
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
A solution of ethyl 3-oxobutanoate (1.95 g, 15 mmol), 4-hydroxy-3-methoxybenzaldehyde (1.52 g, 10.0 mmol) and thiourea (0.76 g, 10 mmol) in ethanol (10 ml) was heated under reflux in the presence of a catalytic amount of HCl for 5 h. The reaction mixture was cooled and filtered. The solid product was recrystallized from ethanol to afford the pure product which was then dissolved in 100 ml absolute ethanol and crystals suitable for X-ray analysis were grown by slow evaporation over a period of 15 d.
The C and O-bound H atoms were positioned geometrically, with C—H = 0.93–0.97 Å and O—H = 0.82 Å, and refined in a riding model, with Uiso(H)= 1.2Ueq(C, O) or 1.5Ueq(methyl C). The positional parameters of the nitrogen-bound H atoms were refined freely, with Uiso(H) = 1.2Ueq(N).
Dihydropyrimidinones (DHPMs) and their derivatives exhibit a wide range of pharmacological and biological activities such as antibacterial, antiviral, antitumor and anti-inflamatory actions (Kappe, 1993).
The title compound, (I), (Fig. 1), was synthesized by the one-pot reaction of 4-hydroxy-3-methoxybenzaldehyde, thiourea and ethyl 3-oxobutanoate in ethanol under reflux. In the arbitrarily chosen asymmetric molecule, C4 has S configuration, but crystal symmetry generates a racemic mixture of enantiomers. The tetrahydropyrimidin-2-one ring is significantly twisted [C3—N2—C4—C5 = 32.8 (3)°]; the phenyl ring is almost perpendicular to the tetrahydropyrimidin-2-one ring [C3—N2—C4—C9 = -93.5 (2)° and C9—C4—C5—C2 = 99.7 (2)°]. The crystal structure is stabilized mainly through intermolecular N—H···S and O—H···O hydrogen bonds (Table 1).
For background, see: Kappe (1993).
Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL (Bruker, 1997).
C15H18N2O4S | Z = 2 |
Mr = 322.37 | F(000) = 340 |
Triclinic, P1 | Dx = 1.388 Mg m−3 |
Hall symbol: -P 1 | Melting point = 518–520 K |
a = 8.469 (2) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.362 (3) Å | Cell parameters from 1562 reflections |
c = 11.183 (3) Å | θ = 2.4–26.1° |
α = 97.935 (4)° | µ = 0.23 mm−1 |
β = 107.783 (4)° | T = 294 K |
γ = 108.777 (4)° | Prism, colorless |
V = 771.4 (4) Å3 | 0.20 × 0.18 × 0.18 mm |
Bruker SMART CCD diffractometer | 2693 independent reflections |
Radiation source: fine-focus sealed tube | 2011 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
ω scans | θmax = 25.0°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | h = −10→4 |
Tmin = 0.956, Tmax = 0.960 | k = −11→11 |
3996 measured reflections | l = −12→13 |
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)] = 0.040 | Hydrogen site location: difmap and geom |
wR(F2) = 0.107 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0443P)2 + 0.4122P] where P = (Fo2 + 2Fc2)/3 |
2693 reflections | (Δ/σ)max = 0.001 |
211 parameters | Δρmax = 0.23 e Å−3 |
2 restraints | Δρmin = −0.26 e Å−3 |
C15H18N2O4S | γ = 108.777 (4)° |
Mr = 322.37 | V = 771.4 (4) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.469 (2) Å | Mo Kα radiation |
b = 9.362 (3) Å | µ = 0.23 mm−1 |
c = 11.183 (3) Å | T = 294 K |
α = 97.935 (4)° | 0.20 × 0.18 × 0.18 mm |
β = 107.783 (4)° |
Bruker SMART CCD diffractometer | 2693 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | 2011 reflections with I > 2σ(I) |
Tmin = 0.956, Tmax = 0.960 | Rint = 0.018 |
3996 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 2 restraints |
wR(F2) = 0.107 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.23 e Å−3 |
2693 reflections | Δρmin = −0.26 e Å−3 |
211 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
S1 | 1.28452 (8) | 0.56315 (7) | 0.51735 (7) | 0.0443 (2) | |
O1 | 0.7638 (2) | −0.18798 (19) | 0.30554 (17) | 0.0447 (4) | |
O2 | 1.0003 (2) | −0.20831 (18) | 0.26755 (18) | 0.0465 (5) | |
O3 | 0.5754 (2) | 0.1860 (3) | −0.18247 (17) | 0.0547 (5) | |
H3 | 0.4890 | 0.2102 | −0.1883 | 0.082* | |
O4 | 0.4557 (2) | 0.2693 (2) | 0.00204 (17) | 0.0524 (5) | |
N1 | 1.2645 (2) | 0.2813 (2) | 0.41844 (19) | 0.0345 (5) | |
N2 | 1.0002 (2) | 0.2943 (2) | 0.41542 (18) | 0.0329 (5) | |
C1 | 1.3338 (3) | 0.0517 (3) | 0.4109 (3) | 0.0441 (6) | |
H1A | 1.2797 | −0.0582 | 0.4025 | 0.066* | |
H1B | 1.4214 | 0.1029 | 0.4974 | 0.066* | |
H1C | 1.3914 | 0.0677 | 0.3493 | 0.066* | |
C2 | 1.1921 (3) | 0.1183 (2) | 0.3851 (2) | 0.0307 (5) | |
C3 | 1.1748 (3) | 0.3695 (3) | 0.4455 (2) | 0.0308 (5) | |
C4 | 0.8943 (3) | 0.1362 (2) | 0.3277 (2) | 0.0295 (5) | |
H4 | 0.7970 | 0.0855 | 0.3565 | 0.035* | |
C5 | 1.0128 (3) | 0.0437 (3) | 0.3421 (2) | 0.0300 (5) | |
C6 | 0.9129 (3) | −0.1276 (3) | 0.3051 (2) | 0.0323 (5) | |
C7 | 0.9108 (4) | −0.3780 (3) | 0.2279 (3) | 0.0479 (7) | |
H7A | 0.7905 | −0.4098 | 0.1638 | 0.058* | |
H7B | 0.9020 | −0.4176 | 0.3024 | 0.058* | |
C8 | 1.0197 (5) | −0.4392 (3) | 0.1721 (3) | 0.0728 (10) | |
H8A | 1.0180 | −0.4073 | 0.0939 | 0.109* | |
H8B | 0.9709 | −0.5513 | 0.1522 | 0.109* | |
H8C | 1.1412 | −0.3990 | 0.2337 | 0.109* | |
C9 | 0.8087 (3) | 0.1452 (2) | 0.1891 (2) | 0.0293 (5) | |
C10 | 0.6679 (3) | 0.1976 (3) | 0.1605 (2) | 0.0325 (5) | |
H10 | 0.6255 | 0.2213 | 0.2251 | 0.039* | |
C11 | 0.5909 (3) | 0.2150 (3) | 0.0391 (2) | 0.0349 (5) | |
C12 | 0.6507 (3) | 0.1751 (3) | −0.0592 (2) | 0.0366 (6) | |
C13 | 0.7897 (3) | 0.1247 (3) | −0.0315 (2) | 0.0401 (6) | |
H13 | 0.8311 | 0.0998 | −0.0963 | 0.048* | |
C14 | 0.8694 (3) | 0.1104 (3) | 0.0923 (2) | 0.0355 (5) | |
H14 | 0.9644 | 0.0771 | 0.1099 | 0.043* | |
C15 | 0.3902 (4) | 0.3151 (4) | 0.0975 (3) | 0.0637 (9) | |
H15A | 0.3406 | 0.2269 | 0.1284 | 0.096* | |
H15B | 0.2987 | 0.3528 | 0.0598 | 0.096* | |
H15C | 0.4872 | 0.3966 | 0.1689 | 0.096* | |
H2 | 0.937 (3) | 0.349 (3) | 0.435 (2) | 0.049 (7)* | |
H1 | 1.3834 (14) | 0.327 (3) | 0.443 (2) | 0.046 (7)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0291 (3) | 0.0336 (3) | 0.0617 (4) | 0.0114 (3) | 0.0146 (3) | −0.0064 (3) |
O1 | 0.0307 (9) | 0.0437 (10) | 0.0550 (11) | 0.0108 (8) | 0.0130 (8) | 0.0142 (8) |
O2 | 0.0449 (10) | 0.0259 (9) | 0.0694 (12) | 0.0104 (7) | 0.0286 (9) | 0.0058 (8) |
O3 | 0.0470 (11) | 0.0894 (15) | 0.0380 (10) | 0.0360 (11) | 0.0156 (9) | 0.0246 (10) |
O4 | 0.0481 (10) | 0.0796 (14) | 0.0451 (11) | 0.0438 (10) | 0.0160 (9) | 0.0205 (10) |
N1 | 0.0229 (10) | 0.0318 (11) | 0.0484 (12) | 0.0126 (8) | 0.0137 (9) | 0.0033 (9) |
N2 | 0.0233 (10) | 0.0351 (11) | 0.0372 (11) | 0.0142 (8) | 0.0090 (8) | −0.0012 (9) |
C1 | 0.0322 (13) | 0.0393 (14) | 0.0563 (17) | 0.0185 (11) | 0.0088 (12) | 0.0051 (12) |
C2 | 0.0309 (12) | 0.0303 (12) | 0.0316 (12) | 0.0156 (10) | 0.0105 (10) | 0.0041 (10) |
C3 | 0.0270 (11) | 0.0355 (12) | 0.0307 (12) | 0.0149 (10) | 0.0105 (9) | 0.0053 (10) |
C4 | 0.0227 (11) | 0.0304 (12) | 0.0330 (12) | 0.0091 (9) | 0.0099 (9) | 0.0048 (10) |
C5 | 0.0286 (12) | 0.0322 (12) | 0.0289 (12) | 0.0131 (10) | 0.0092 (9) | 0.0075 (10) |
C6 | 0.0323 (13) | 0.0364 (13) | 0.0277 (12) | 0.0150 (10) | 0.0075 (10) | 0.0114 (10) |
C7 | 0.0550 (16) | 0.0281 (13) | 0.0557 (17) | 0.0090 (12) | 0.0226 (13) | 0.0081 (12) |
C8 | 0.094 (3) | 0.0384 (16) | 0.088 (2) | 0.0178 (16) | 0.049 (2) | 0.0084 (16) |
C9 | 0.0226 (11) | 0.0247 (11) | 0.0354 (13) | 0.0070 (9) | 0.0080 (9) | 0.0040 (9) |
C10 | 0.0291 (12) | 0.0342 (12) | 0.0347 (13) | 0.0132 (10) | 0.0135 (10) | 0.0045 (10) |
C11 | 0.0269 (12) | 0.0380 (13) | 0.0372 (14) | 0.0143 (10) | 0.0070 (10) | 0.0089 (10) |
C12 | 0.0312 (12) | 0.0420 (14) | 0.0329 (13) | 0.0126 (11) | 0.0089 (10) | 0.0095 (11) |
C13 | 0.0377 (13) | 0.0499 (15) | 0.0375 (14) | 0.0205 (12) | 0.0172 (11) | 0.0099 (12) |
C14 | 0.0295 (12) | 0.0398 (13) | 0.0404 (14) | 0.0184 (10) | 0.0128 (10) | 0.0085 (11) |
C15 | 0.0586 (18) | 0.096 (2) | 0.0614 (19) | 0.0567 (18) | 0.0254 (15) | 0.0233 (18) |
S1—C3 | 1.689 (2) | C4—H4 | 0.9800 |
O1—C6 | 1.208 (3) | C5—C6 | 1.479 (3) |
O2—C6 | 1.326 (3) | C7—C8 | 1.470 (4) |
O2—C7 | 1.456 (3) | C7—H7A | 0.9700 |
O3—C12 | 1.364 (3) | C7—H7B | 0.9700 |
O3—H3 | 0.8200 | C8—H8A | 0.9600 |
O4—C11 | 1.373 (3) | C8—H8B | 0.9600 |
O4—C15 | 1.421 (3) | C8—H8C | 0.9600 |
N1—C3 | 1.352 (3) | C9—C14 | 1.375 (3) |
N1—C2 | 1.395 (3) | C9—C10 | 1.397 (3) |
N1—H1 | 0.891 (10) | C10—C11 | 1.372 (3) |
N2—C3 | 1.325 (3) | C10—H10 | 0.9300 |
N2—C4 | 1.471 (3) | C11—C12 | 1.398 (3) |
N2—H2 | 0.90 (3) | C12—C13 | 1.371 (3) |
C1—C2 | 1.494 (3) | C13—C14 | 1.389 (3) |
C1—H1A | 0.9600 | C13—H13 | 0.9300 |
C1—H1B | 0.9600 | C14—H14 | 0.9300 |
C1—H1C | 0.9600 | C15—H15A | 0.9600 |
C2—C5 | 1.343 (3) | C15—H15B | 0.9600 |
C4—C5 | 1.510 (3) | C15—H15C | 0.9600 |
C4—C9 | 1.524 (3) | ||
C6—O2—C7 | 117.25 (19) | C8—C7—H7A | 110.3 |
C12—O3—H3 | 109.5 | O2—C7—H7B | 110.3 |
C11—O4—C15 | 117.87 (19) | C8—C7—H7B | 110.3 |
C3—N1—C2 | 123.52 (18) | H7A—C7—H7B | 108.6 |
C3—N1—H1 | 118.4 (17) | C7—C8—H8A | 109.5 |
C2—N1—H1 | 116.1 (17) | C7—C8—H8B | 109.5 |
C3—N2—C4 | 124.04 (18) | H8A—C8—H8B | 109.5 |
C3—N2—H2 | 118.4 (17) | C7—C8—H8C | 109.5 |
C4—N2—H2 | 116.3 (17) | H8A—C8—H8C | 109.5 |
C2—C1—H1A | 109.5 | H8B—C8—H8C | 109.5 |
C2—C1—H1B | 109.5 | C14—C9—C10 | 118.5 (2) |
H1A—C1—H1B | 109.5 | C14—C9—C4 | 122.74 (19) |
C2—C1—H1C | 109.5 | C10—C9—C4 | 118.7 (2) |
H1A—C1—H1C | 109.5 | C11—C10—C9 | 121.4 (2) |
H1B—C1—H1C | 109.5 | C11—C10—H10 | 119.3 |
C5—C2—N1 | 118.47 (19) | C9—C10—H10 | 119.3 |
C5—C2—C1 | 129.1 (2) | C10—C11—O4 | 126.0 (2) |
N1—C2—C1 | 112.37 (18) | C10—C11—C12 | 119.4 (2) |
N2—C3—N1 | 116.1 (2) | O4—C11—C12 | 114.6 (2) |
N2—C3—S1 | 123.25 (16) | O3—C12—C13 | 118.8 (2) |
N1—C3—S1 | 120.65 (16) | O3—C12—C11 | 121.8 (2) |
N2—C4—C5 | 108.71 (16) | C13—C12—C11 | 119.5 (2) |
N2—C4—C9 | 110.28 (17) | C12—C13—C14 | 120.8 (2) |
C5—C4—C9 | 114.55 (18) | C12—C13—H13 | 119.6 |
N2—C4—H4 | 107.7 | C14—C13—H13 | 119.6 |
C5—C4—H4 | 107.7 | C9—C14—C13 | 120.4 (2) |
C9—C4—H4 | 107.7 | C9—C14—H14 | 119.8 |
C2—C5—C6 | 126.0 (2) | C13—C14—H14 | 119.8 |
C2—C5—C4 | 119.97 (19) | O4—C15—H15A | 109.5 |
C6—C5—C4 | 114.02 (18) | O4—C15—H15B | 109.5 |
O1—C6—O2 | 123.2 (2) | H15A—C15—H15B | 109.5 |
O1—C6—C5 | 123.2 (2) | O4—C15—H15C | 109.5 |
O2—C6—C5 | 113.57 (19) | H15A—C15—H15C | 109.5 |
O2—C7—C8 | 107.1 (2) | H15B—C15—H15C | 109.5 |
O2—C7—H7A | 110.3 | ||
C3—N1—C2—C5 | 19.3 (3) | C4—C5—C6—O2 | 154.47 (19) |
C3—N1—C2—C1 | −157.4 (2) | C6—O2—C7—C8 | 171.4 (2) |
C4—N2—C3—N1 | −16.1 (3) | N2—C4—C9—C14 | 106.3 (2) |
C4—N2—C3—S1 | 165.59 (17) | C5—C4—C9—C14 | −16.8 (3) |
C2—N1—C3—N2 | −12.3 (3) | N2—C4—C9—C10 | −70.8 (2) |
C2—N1—C3—S1 | 166.09 (17) | C5—C4—C9—C10 | 166.18 (19) |
C3—N2—C4—C5 | 32.8 (3) | C14—C9—C10—C11 | −0.2 (3) |
C3—N2—C4—C9 | −93.5 (2) | C4—C9—C10—C11 | 177.04 (19) |
N1—C2—C5—C6 | −178.7 (2) | C9—C10—C11—O4 | −178.2 (2) |
C1—C2—C5—C6 | −2.5 (4) | C9—C10—C11—C12 | 1.9 (3) |
N1—C2—C5—C4 | 1.5 (3) | C15—O4—C11—C10 | 1.3 (4) |
C1—C2—C5—C4 | 177.7 (2) | C15—O4—C11—C12 | −178.8 (2) |
N2—C4—C5—C2 | −24.2 (3) | C10—C11—C12—O3 | 178.2 (2) |
C9—C4—C5—C2 | 99.7 (2) | O4—C11—C12—O3 | −1.8 (3) |
N2—C4—C5—C6 | 155.99 (18) | C10—C11—C12—C13 | −2.4 (3) |
C9—C4—C5—C6 | −80.2 (2) | O4—C11—C12—C13 | 177.7 (2) |
C7—O2—C6—O1 | −1.3 (3) | O3—C12—C13—C14 | −179.4 (2) |
C7—O2—C6—C5 | −179.36 (19) | C11—C12—C13—C14 | 1.1 (4) |
C2—C5—C6—O1 | 156.6 (2) | C10—C9—C14—C13 | −1.1 (3) |
C4—C5—C6—O1 | −23.6 (3) | C4—C9—C14—C13 | −178.2 (2) |
C2—C5—C6—O2 | −25.3 (3) | C12—C13—C14—C9 | 0.7 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1i | 0.82 | 2.07 | 2.788 (2) | 147 |
O3—H3···O4 | 0.82 | 2.25 | 2.690 (3) | 114 |
N2—H2···S1ii | 0.90 (3) | 2.44 (3) | 3.326 (2) | 167 (2) |
N1—H1···S1iii | 0.89 (1) | 2.53 (1) | 3.417 (2) | 173 (2) |
Symmetry codes: (i) −x+1, −y, −z; (ii) −x+2, −y+1, −z+1; (iii) −x+3, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C15H18N2O4S |
Mr | 322.37 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 294 |
a, b, c (Å) | 8.469 (2), 9.362 (3), 11.183 (3) |
α, β, γ (°) | 97.935 (4), 107.783 (4), 108.777 (4) |
V (Å3) | 771.4 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.23 |
Crystal size (mm) | 0.20 × 0.18 × 0.18 |
Data collection | |
Diffractometer | Bruker SMART CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 1997) |
Tmin, Tmax | 0.956, 0.960 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3996, 2693, 2011 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.107, 1.02 |
No. of reflections | 2693 |
No. of parameters | 211 |
No. of restraints | 2 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.23, −0.26 |
Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1i | 0.82 | 2.07 | 2.788 (2) | 147 |
O3—H3···O4 | 0.82 | 2.25 | 2.690 (3) | 114 |
N2—H2···S1ii | 0.90 (3) | 2.44 (3) | 3.326 (2) | 167 (2) |
N1—H1···S1iii | 0.891 (10) | 2.531 (11) | 3.417 (2) | 173 (2) |
Symmetry codes: (i) −x+1, −y, −z; (ii) −x+2, −y+1, −z+1; (iii) −x+3, −y+1, −z+1. |
Dihydropyrimidinones (DHPMs) and their derivatives exhibit a wide range of pharmacological and biological activities such as antibacterial, antiviral, antitumor and anti-inflamatory actions (Kappe, 1993).
The title compound, (I), (Fig. 1), was synthesized by the one-pot reaction of 4-hydroxy-3-methoxybenzaldehyde, thiourea and ethyl 3-oxobutanoate in ethanol under reflux. In the arbitrarily chosen asymmetric molecule, C4 has S configuration, but crystal symmetry generates a racemic mixture of enantiomers. The tetrahydropyrimidin-2-one ring is significantly twisted [C3—N2—C4—C5 = 32.8 (3)°]; the phenyl ring is almost perpendicular to the tetrahydropyrimidin-2-one ring [C3—N2—C4—C9 = -93.5 (2)° and C9—C4—C5—C2 = 99.7 (2)°]. The crystal structure is stabilized mainly through intermolecular N—H···S and O—H···O hydrogen bonds (Table 1).