organic compounds
tert-Butyl 4-(4-chloroanilino)-6-methyl-2-oxocyclohex-3-enecarboxylate
aDepartment of Pharmaceutical Sciences, Howard University, 2300 4th Street NW, Washington, DC 20059, USA, and bDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA
*Correspondence e-mail: rbutcher99@yahoo.com
In the title compound, C18H22ClNO3, the dihedral angle between the benzene ring and the conjugated part of the enaminone ring is 55.19 (9)°. The ester substituent makes a dihedral angle of 81.0 (2)° with this latter moiety. The features N—H⋯O and weak C—H⋯O intermolecular interactions.
Related literature
Our research on enaminones has led to several compounds possessing anticonvulsant properties, see: Edafiogho et al. (1992); Eddington et al. (2003); Scott et al. (1993, 1995).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.
Supporting information
https://doi.org/10.1107/S1600536810051743/om2378sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810051743/om2378Isup2.hkl
4-Carbo-tert-butoxy-5-methylcyclohexane-1,3-dione (6. 11 g, 27 mmol), mp 145–146° C (lit. mp 130–131.5°C),7 and 4-chloroaniline (4.21 g, 33 mmol) were added to a mixture of absolute EtOH (100 ml) and EtOAc (100 ml), and the solution was refluxed and stirred for 6 h. Evaporation under reduced pressure yielded a yellow solid which was recrystallized from 2-PrOH: yield 3.96 g (43%); mp 190–192° C; 1H NMR (CDC13) 6 1.10 (3H, d, J = 6.3 Hz, CH3), 1.48 (9H, s, 3 x CH3 of tert-butyl group), 2.22–2.63 (3H, m, CH2 + CH of cyclohexene ring), 2.90 (lH, d, J =11.0 Hz, CHI, 5.45 (lH, 8, =CHI, 6.90 (lH, bs, NH), 7.05–7.30 (4H, m, C6H4).
H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C—H distance of 0.93 and 0.98 Å Uiso(H) = 1.2Ueq(C) and 0.96 Å for CH3 [Uiso(H) = 1.5Ueq(C)]. The H atoms attached to N were idealized with an N–H distance of 0.86 Å.
Our research on enaminones has led to several compounds possessing anticonvulsant properties (Edafiogho et al., 1992; Eddington et al., 2003; Scott et al., 1993, 1995). The present work is part of a structural study of enaminones. Our group has extensively studied the effects of modification of the enaminone with substitutions at the methyl ester, ethyl ester, and without the ester group. We synthesized a series of carbo-tert-butoxy
to evaluate the effect of added bulk and to the ester functionality. These compounds showed significant anticonvulsant activity. The title compound, tert-butyl- 4-(4-chlorophenlyamino)-6-methyl-2-oxocyclohex-3-enecarboxylate is highly active, with activity at <100 mg kg-1. The compound was active in maximal electroshock seizure evaluation (MES) in mice, indicative of protection against tonic-clonic convulsions in humans (1/4 rats protected at 1 h, 2 h and 4 h post dose at 50 mg kg dose). Toxicity tests showed no toxicity in rats (oral) up to 4 h at 50 mg/kg per dose. The MES study in mice showed 1/1 animals were protected at 300 mg/kg at 30 minutes. In 4 h testing, 3/3 animals were protected at 100 mg/kg and 1/1 animals protected at 300 mg/kg dose. In toxicity studies, at 15 min, 2/8 mice (ip = interperitoneal) showed toxicity at 500 mg/kg dose. A 2 h MES protection test in mice (ip) displayed 3/8 animals protected at 85 mg/kg dose, 4/8 animals protected at 100 mg/kg, and 7/8 animals were protected at 170 mg/kg (optimum dose). In mice, the MES ED50 (median effective dose) of 106.34 mg kg-1 and TD50 (median toxic dose) of 500 mg kg-1 TD, 95% confidence inteval. The scMET (subcuntaneous metrazole) test showed no protection at 250 or 500 mg/kg during a 2 h range.In view of the therapeutic interest in this compound its structure was determined. The conformation adopted by the molecule is such that the dihedral angle between the phenyl ring and conjugated part of the enaminone ring is 55.19 (9)°. The ester substituent makes a dihedral angle of 81.0 (2)° with this latter moiety. The
is held together by strong N—H···O and weak C—H···O intermolecular interactions.Our research on enaminones has led to several compounds possessing
anticonvulsant properties, see: Edafiogho et al. (1992); Eddington et al. (2003); Scott et al. (1993, 1995).
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell
CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis PRO (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C18H22ClNO3 | Dx = 1.262 Mg m−3 |
Mr = 335.82 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 5335 reflections |
a = 11.0801 (3) Å | θ = 4.5–77.5° |
b = 10.9095 (3) Å | µ = 0.23 mm−1 |
c = 29.2474 (7) Å | T = 295 K |
V = 3535.39 (16) Å3 | Plate, colorless |
Z = 8 | 0.45 × 0.38 × 0.08 mm |
F(000) = 1424 |
Oxford Diffraction Xcalibur Ruby Gemini diffractometer | 3708 independent reflections |
Radiation source: Enhance (Cu) X-ray Source | 2925 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
Detector resolution: 10.5081 pixels mm-1 | θmax = 26.8°, θmin = 2.3° |
ω scans | h = −13→14 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | k = −13→7 |
Tmin = 0.93, Tmax = 0.98 | l = −22→36 |
9798 measured reflections |
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.172 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.1062P)2 + 0.3243P] where P = (Fo2 + 2Fc2)/3 |
3708 reflections | (Δ/σ)max < 0.001 |
212 parameters | Δρmax = 0.39 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C18H22ClNO3 | V = 3535.39 (16) Å3 |
Mr = 335.82 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 11.0801 (3) Å | µ = 0.23 mm−1 |
b = 10.9095 (3) Å | T = 295 K |
c = 29.2474 (7) Å | 0.45 × 0.38 × 0.08 mm |
Oxford Diffraction Xcalibur Ruby Gemini diffractometer | 3708 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | 2925 reflections with I > 2σ(I) |
Tmin = 0.93, Tmax = 0.98 | Rint = 0.030 |
9798 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.172 | H-atom parameters constrained |
S = 1.09 | Δρmax = 0.39 e Å−3 |
3708 reflections | Δρmin = −0.25 e Å−3 |
212 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 | ||
Cl1 | 0.91865 (8) | 0.65446 (7) | 0.66441 (3) | 0.0944 (3) | |
O1 | 0.91038 (13) | 0.17651 (17) | 0.43476 (6) | 0.0689 (4) | |
O2 | 0.7403 (2) | 0.01470 (14) | 0.37719 (6) | 0.0785 (5) | |
O3 | 0.78836 (13) | 0.16309 (12) | 0.32703 (4) | 0.0545 (3) | |
N1 | 0.63017 (13) | 0.40873 (17) | 0.52106 (5) | 0.0539 (4) | |
H1 | 0.5536 | 0.4180 | 0.5243 | 0.065* | |
C1 | 0.70410 (16) | 0.46315 (18) | 0.55484 (6) | 0.0492 (4) | |
C2 | 0.8068 (2) | 0.5287 (2) | 0.54365 (7) | 0.0628 (5) | |
H2 | 0.8314 | 0.5333 | 0.5133 | 0.075* | |
C3 | 0.8732 (2) | 0.5875 (2) | 0.57713 (8) | 0.0682 (6) | |
H3 | 0.9429 | 0.6305 | 0.5695 | 0.082* | |
C4 | 0.8349 (2) | 0.5817 (2) | 0.62193 (7) | 0.0621 (5) | |
C5 | 0.7323 (2) | 0.5180 (2) | 0.63334 (7) | 0.0659 (5) | |
H5 | 0.7068 | 0.5154 | 0.6636 | 0.079* | |
C6 | 0.66736 (17) | 0.4583 (2) | 0.60016 (6) | 0.0584 (5) | |
H6 | 0.5985 | 0.4144 | 0.6081 | 0.070* | |
C7 | 0.66666 (15) | 0.34364 (17) | 0.48417 (5) | 0.0447 (4) | |
C8 | 0.56893 (15) | 0.32234 (19) | 0.44950 (6) | 0.0507 (4) | |
H8A | 0.5601 | 0.3956 | 0.4310 | 0.061* | |
H8B | 0.4933 | 0.3091 | 0.4654 | 0.061* | |
C9 | 0.59232 (15) | 0.21420 (18) | 0.41826 (6) | 0.0489 (4) | |
H9 | 0.5873 | 0.1391 | 0.4365 | 0.059* | |
C10 | 0.72128 (15) | 0.22487 (16) | 0.39930 (6) | 0.0447 (4) | |
H10A | 0.7270 | 0.3016 | 0.3820 | 0.054* | |
C11 | 0.81263 (14) | 0.23012 (17) | 0.43840 (6) | 0.0472 (4) | |
C12 | 0.78047 (15) | 0.29974 (18) | 0.47760 (6) | 0.0485 (4) | |
H12 | 0.8391 | 0.3159 | 0.4995 | 0.058* | |
C13 | 0.49731 (19) | 0.2070 (2) | 0.38044 (7) | 0.0635 (5) | |
H13A | 0.4184 | 0.2022 | 0.3939 | 0.095* | |
H13B | 0.5115 | 0.1355 | 0.3621 | 0.095* | |
H13C | 0.5024 | 0.2789 | 0.3616 | 0.095* | |
C14 | 0.75164 (18) | 0.12016 (16) | 0.36732 (6) | 0.0507 (4) | |
C15 | 0.8185 (2) | 0.0796 (2) | 0.28902 (6) | 0.0586 (5) | |
C16 | 0.9248 (3) | 0.0025 (4) | 0.30166 (10) | 0.1008 (11) | |
H16C | 0.9005 | −0.0585 | 0.3234 | 0.151* | |
H16D | 0.9863 | 0.0534 | 0.3149 | 0.151* | |
H16A | 0.9560 | −0.0368 | 0.2748 | 0.151* | |
C17 | 0.8512 (4) | 0.1665 (3) | 0.25068 (9) | 0.0955 (10) | |
H17A | 0.9144 | 0.2205 | 0.2607 | 0.143* | |
H17B | 0.7816 | 0.2139 | 0.2423 | 0.143* | |
H17C | 0.8783 | 0.1204 | 0.2247 | 0.143* | |
C18 | 0.7086 (3) | 0.0050 (4) | 0.27656 (11) | 0.1025 (11) | |
H18A | 0.6868 | −0.0465 | 0.3019 | 0.154* | |
H18B | 0.7264 | −0.0450 | 0.2504 | 0.154* | |
H18C | 0.6428 | 0.0590 | 0.2695 | 0.154* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1 | 0.1084 (6) | 0.0928 (5) | 0.0821 (4) | −0.0154 (4) | −0.0342 (4) | −0.0178 (4) |
O1 | 0.0460 (7) | 0.0958 (11) | 0.0648 (9) | 0.0202 (7) | −0.0022 (6) | −0.0154 (8) |
O2 | 0.1255 (15) | 0.0446 (8) | 0.0653 (9) | 0.0057 (8) | 0.0129 (9) | 0.0027 (7) |
O3 | 0.0694 (8) | 0.0495 (7) | 0.0446 (6) | 0.0010 (6) | 0.0015 (6) | −0.0036 (5) |
N1 | 0.0414 (7) | 0.0721 (10) | 0.0481 (8) | 0.0038 (7) | 0.0036 (6) | −0.0087 (7) |
C1 | 0.0474 (8) | 0.0557 (10) | 0.0443 (8) | 0.0047 (7) | 0.0002 (6) | −0.0028 (7) |
C2 | 0.0743 (13) | 0.0642 (12) | 0.0499 (10) | −0.0136 (10) | 0.0051 (9) | 0.0020 (9) |
C3 | 0.0743 (13) | 0.0604 (12) | 0.0700 (12) | −0.0195 (11) | −0.0015 (10) | 0.0011 (10) |
C4 | 0.0714 (12) | 0.0577 (11) | 0.0571 (10) | 0.0041 (9) | −0.0161 (9) | −0.0065 (9) |
C5 | 0.0642 (11) | 0.0887 (15) | 0.0447 (9) | 0.0067 (11) | −0.0011 (8) | −0.0058 (10) |
C6 | 0.0470 (9) | 0.0802 (13) | 0.0479 (9) | 0.0015 (9) | 0.0032 (7) | −0.0037 (9) |
C7 | 0.0413 (8) | 0.0528 (9) | 0.0399 (7) | −0.0010 (7) | 0.0017 (6) | 0.0020 (7) |
C8 | 0.0364 (7) | 0.0677 (11) | 0.0480 (8) | 0.0020 (7) | −0.0013 (6) | −0.0027 (8) |
C9 | 0.0441 (8) | 0.0538 (10) | 0.0489 (9) | −0.0056 (7) | −0.0048 (7) | 0.0038 (7) |
C10 | 0.0476 (8) | 0.0448 (8) | 0.0418 (8) | −0.0005 (6) | −0.0001 (6) | 0.0007 (7) |
C11 | 0.0383 (7) | 0.0561 (9) | 0.0471 (8) | 0.0006 (7) | 0.0020 (6) | 0.0001 (7) |
C12 | 0.0378 (7) | 0.0630 (10) | 0.0445 (8) | 0.0029 (7) | −0.0034 (6) | −0.0022 (7) |
C13 | 0.0538 (10) | 0.0735 (13) | 0.0633 (11) | −0.0086 (9) | −0.0151 (9) | −0.0045 (10) |
C14 | 0.0575 (9) | 0.0469 (9) | 0.0478 (9) | 0.0033 (8) | −0.0038 (7) | −0.0005 (7) |
C15 | 0.0693 (11) | 0.0613 (11) | 0.0451 (9) | 0.0034 (9) | −0.0008 (8) | −0.0103 (8) |
C16 | 0.102 (2) | 0.126 (3) | 0.0742 (16) | 0.051 (2) | 0.0111 (15) | −0.0059 (17) |
C17 | 0.147 (3) | 0.0849 (17) | 0.0544 (13) | −0.0033 (19) | 0.0192 (16) | −0.0025 (12) |
C18 | 0.102 (2) | 0.125 (3) | 0.0800 (17) | −0.0311 (19) | 0.0000 (15) | −0.0427 (18) |
Cl1—C4 | 1.742 (2) | C9—C13 | 1.529 (2) |
O1—C11 | 1.235 (2) | C9—C10 | 1.537 (2) |
O2—C14 | 1.193 (3) | C9—H9 | 0.9800 |
O3—C14 | 1.332 (2) | C10—C14 | 1.514 (2) |
O3—C15 | 1.475 (2) | C10—C11 | 1.528 (2) |
N1—C7 | 1.353 (2) | C10—H10A | 0.9800 |
N1—C1 | 1.414 (2) | C11—C12 | 1.421 (2) |
N1—H1 | 0.8600 | C12—H12 | 0.9300 |
C1—C2 | 1.383 (3) | C13—H13A | 0.9600 |
C1—C6 | 1.388 (3) | C13—H13B | 0.9600 |
C2—C3 | 1.383 (3) | C13—H13C | 0.9600 |
C2—H2 | 0.9300 | C15—C16 | 1.494 (3) |
C3—C4 | 1.379 (3) | C15—C18 | 1.509 (3) |
C3—H3 | 0.9300 | C15—C17 | 1.512 (3) |
C4—C5 | 1.373 (3) | C16—H16C | 0.9600 |
C5—C6 | 1.373 (3) | C16—H16D | 0.9600 |
C5—H5 | 0.9300 | C16—H16A | 0.9600 |
C6—H6 | 0.9300 | C17—H17A | 0.9600 |
C7—C12 | 1.363 (2) | C17—H17B | 0.9600 |
C7—C8 | 1.502 (2) | C17—H17C | 0.9600 |
C8—C9 | 1.515 (3) | C18—H18A | 0.9600 |
C8—H8A | 0.9700 | C18—H18B | 0.9600 |
C8—H8B | 0.9700 | C18—H18C | 0.9600 |
C14—O3—C15 | 121.26 (15) | C11—C10—H10 | 108.1 |
C7—N1—C1 | 127.17 (15) | C9—C10—H10 | 108.1 |
C7—N1—H1 | 116.4 | O1—C11—C12 | 122.87 (17) |
C1—N1—H1 | 116.4 | O1—C11—C10 | 119.88 (16) |
C2—C1—C6 | 119.15 (18) | C12—C11—C10 | 117.24 (15) |
C2—C1—N1 | 121.90 (17) | C7—C12—C11 | 122.28 (16) |
C6—C1—N1 | 118.77 (17) | C7—C12—H12 | 118.9 |
C3—C2—C1 | 120.67 (19) | C11—C12—H12 | 118.9 |
C3—C2—H2 | 119.7 | C9—C13—H13A | 109.5 |
C1—C2—H2 | 119.7 | C9—C13—H13B | 109.5 |
C4—C3—C2 | 119.2 (2) | H13A—C13—H13B | 109.5 |
C4—C3—H3 | 120.4 | C9—C13—H13C | 109.5 |
C2—C3—H3 | 120.4 | H13A—C13—H13C | 109.5 |
C5—C4—C3 | 120.60 (19) | H13B—C13—H13C | 109.5 |
C5—C4—Cl1 | 119.86 (17) | O2—C14—O3 | 125.85 (18) |
C3—C4—Cl1 | 119.54 (19) | O2—C14—C10 | 123.68 (18) |
C6—C5—C4 | 120.15 (19) | O3—C14—C10 | 110.43 (15) |
C6—C5—H5 | 119.9 | O3—C15—C16 | 109.85 (18) |
C4—C5—H5 | 119.9 | O3—C15—C18 | 109.42 (19) |
C5—C6—C1 | 120.22 (19) | C16—C15—C18 | 113.1 (3) |
C5—C6—H6 | 119.9 | O3—C15—C17 | 103.07 (18) |
C1—C6—H6 | 119.9 | C16—C15—C17 | 110.3 (2) |
N1—C7—C12 | 124.99 (16) | C18—C15—C17 | 110.6 (2) |
N1—C7—C8 | 113.84 (15) | C15—C16—H16C | 109.5 |
C12—C7—C8 | 121.18 (15) | C15—C16—H16D | 109.5 |
C7—C8—C9 | 113.86 (15) | H16C—C16—H16D | 109.5 |
C7—C8—H8A | 108.8 | C15—C16—H16A | 109.5 |
C9—C8—H8A | 108.8 | H16C—C16—H16A | 109.5 |
C7—C8—H8B | 108.8 | H16D—C16—H16A | 109.5 |
C9—C8—H8B | 108.8 | C15—C17—H17A | 109.5 |
H8A—C8—H8B | 107.7 | C15—C17—H17B | 109.5 |
C8—C9—C13 | 111.01 (16) | H17A—C17—H17B | 109.5 |
C8—C9—C10 | 108.52 (14) | C15—C17—H17C | 109.5 |
C13—C9—C10 | 112.52 (16) | H17A—C17—H17C | 109.5 |
C8—C9—H9 | 108.2 | H17B—C17—H17C | 109.5 |
C13—C9—H9 | 108.2 | C15—C18—H18A | 109.5 |
C10—C9—H9 | 108.2 | C15—C18—H18B | 109.5 |
C14—C10—C11 | 110.08 (14) | H18A—C18—H18B | 109.5 |
C14—C10—C9 | 111.85 (15) | C15—C18—H18C | 109.5 |
C11—C10—C9 | 110.40 (14) | H18A—C18—H18C | 109.5 |
C14—C10—H10 | 108.1 | H18B—C18—H18C | 109.5 |
C7—N1—C1—C2 | 44.5 (3) | C8—C9—C10—C11 | 57.46 (19) |
C7—N1—C1—C6 | −140.4 (2) | C13—C9—C10—C11 | −179.30 (17) |
C6—C1—C2—C3 | 0.8 (3) | C14—C10—C11—O1 | 17.6 (2) |
N1—C1—C2—C3 | 175.9 (2) | C9—C10—C11—O1 | 141.56 (18) |
C1—C2—C3—C4 | −1.0 (4) | C14—C10—C11—C12 | −163.43 (16) |
C2—C3—C4—C5 | 0.2 (4) | C9—C10—C11—C12 | −39.5 (2) |
C2—C3—C4—Cl1 | 179.48 (19) | N1—C7—C12—C11 | 178.91 (18) |
C3—C4—C5—C6 | 0.7 (4) | C8—C7—C12—C11 | −1.1 (3) |
Cl1—C4—C5—C6 | −178.60 (18) | O1—C11—C12—C7 | −170.34 (19) |
C4—C5—C6—C1 | −0.8 (3) | C10—C11—C12—C7 | 10.7 (3) |
C2—C1—C6—C5 | 0.1 (3) | C15—O3—C14—O2 | 0.7 (3) |
N1—C1—C6—C5 | −175.1 (2) | C15—O3—C14—C10 | −177.35 (16) |
C1—N1—C7—C12 | 12.9 (3) | C11—C10—C14—O2 | 70.1 (3) |
C1—N1—C7—C8 | −167.05 (18) | C9—C10—C14—O2 | −53.0 (3) |
N1—C7—C8—C9 | −158.30 (16) | C11—C10—C14—O3 | −111.80 (17) |
C12—C7—C8—C9 | 21.7 (3) | C9—C10—C14—O3 | 125.08 (17) |
C7—C8—C9—C13 | −173.31 (16) | C14—O3—C15—C16 | −64.0 (3) |
C7—C8—C9—C10 | −49.2 (2) | C14—O3—C15—C18 | 60.7 (3) |
C8—C9—C10—C14 | −179.60 (14) | C14—O3—C15—C17 | 178.4 (2) |
C13—C9—C10—C14 | −56.4 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.86 | 2.24 | 2.909 (2) | 135 |
C6—H6···O1i | 0.93 | 2.63 | 3.363 (2) | 137 |
C10—H10···O2ii | 0.98 | 2.36 | 3.255 (2) | 152 |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) −x+3/2, y+1/2, z. |
Experimental details
Crystal data | |
Chemical formula | C18H22ClNO3 |
Mr | 335.82 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 295 |
a, b, c (Å) | 11.0801 (3), 10.9095 (3), 29.2474 (7) |
V (Å3) | 3535.39 (16) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.23 |
Crystal size (mm) | 0.45 × 0.38 × 0.08 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Ruby Gemini |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.93, 0.98 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9798, 3708, 2925 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.634 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.172, 1.09 |
No. of reflections | 3708 |
No. of parameters | 212 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.39, −0.25 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.86 | 2.24 | 2.909 (2) | 134.8 |
C6—H6···O1i | 0.93 | 2.63 | 3.363 (2) | 136.6 |
C10—H10···O2ii | 0.98 | 2.36 | 3.255 (2) | 152.0 |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) −x+3/2, y+1/2, z. |
Acknowledgements
The authors are indebted to Mr James P. Stables, Epilepsy Branch, Division of Convulsive, Developmental and Neuromuscular Disorders, National Institute of Neurological Disorders and Stroke, for helpful discussions and initial data. The authors wish to acknowledge E. Jeannette Andrews, EdD Deputy Director of the Center of Excellence at Howard University College of Pharmacy, Nursing and Allied Health Sciences, for her generous assistance in completing this project. RJB wishes to acknowledge the NSF–MRI program (grant CHE-0619278) for funds to purchase the diffractometer.
References
Edafiogho, I. O., Hinko, C. N., Chang, H., Moore, J. A., Mulzac, D., Nicholson, J. M. & Scott, K. R. (1992). J. Med. Chem. 35, 2798–2805. CrossRef PubMed CAS Web of Science Google Scholar
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Our research on enaminones has led to several compounds possessing anticonvulsant properties (Edafiogho et al., 1992; Eddington et al., 2003; Scott et al., 1993, 1995). The present work is part of a structural study of enaminones. Our group has extensively studied the effects of modification of the enaminone with substitutions at the methyl ester, ethyl ester, and without the ester group. We synthesized a series of carbo-tert-butoxy esters to evaluate the effect of added bulk and lipophilicity to the ester functionality. These compounds showed significant anticonvulsant activity. The title compound, tert-butyl- 4-(4-chlorophenlyamino)-6-methyl-2-oxocyclohex-3-enecarboxylate is highly active, with activity at <100 mg kg-1. The compound was active in maximal electroshock seizure evaluation (MES) in mice, indicative of protection against tonic-clonic convulsions in humans (1/4 rats protected at 1 h, 2 h and 4 h post dose at 50 mg kg dose). Toxicity tests showed no toxicity in rats (oral) up to 4 h at 50 mg/kg per dose. The MES study in mice showed 1/1 animals were protected at 300 mg/kg at 30 minutes. In 4 h testing, 3/3 animals were protected at 100 mg/kg and 1/1 animals protected at 300 mg/kg dose. In toxicity studies, at 15 min, 2/8 mice (ip = interperitoneal) showed toxicity at 500 mg/kg dose. A 2 h MES protection test in mice (ip) displayed 3/8 animals protected at 85 mg/kg dose, 4/8 animals protected at 100 mg/kg, and 7/8 animals were protected at 170 mg/kg (optimum dose). In mice, the MES ED50 (median effective dose) of 106.34 mg kg-1 and TD50 (median toxic dose) of 500 mg kg-1 TD, 95% confidence inteval. The scMET (subcuntaneous metrazole) test showed no protection at 250 or 500 mg/kg during a 2 h range.
In view of the therapeutic interest in this compound its structure was determined. The conformation adopted by the molecule is such that the dihedral angle between the phenyl ring and conjugated part of the enaminone ring is 55.19 (9)°. The ester substituent makes a dihedral angle of 81.0 (2)° with this latter moiety. The crystal structure is held together by strong N—H···O and weak C—H···O intermolecular interactions.