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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 65| Part 11| November 2009| Page o2728
https://doi.org/10.1107/S160053680903949X

(Z)-Ethyl 3-(2,4,6-tri­methyl­anilino)but-2-enoate

Manuel Amézquita-Valencia,a* Simón Hernández-Ortega,a* G. Alejandra Suárez-Ortiz,a Rubén Alfredo Toscanoa and Armando Cabreraa

aInstituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04510, Mexico
*Correspondence e-mail: majo00@yahoo.com, simonho@unam.mx

(Received 24 September 2009; accepted 28 September 2009; online 17 October 2009)

The title compound, C15H21NO2, was obtained by the reaction of acetoacetate with 2,4,6-trimethyl­aniline using Mexican bentonitic clay as a catalyst. It crystallizes in the enamine form. The β-enamino ester residue is almost perpendicular to the aromatic ring [dihedral angle = 88.10 (6)°]. The mol­ecular conformation is stabilized by a strong intra­molecular N—H⋯O hydrogen bond. In addition, the N—H group forms a weak inter­molecular N—H⋯O hydrogen bond linking the mol­ecules into centrosymmetric dimers.

Related literature

For enamino esters as inter­mediates in the synthesis of natural products, see: Marchand et al. (1994[Marchand, P., Fargeau-Bellassoued, M., Bellec, C. & Lhommet, G. (1994). Synthesis, pp. 1118-1120.]). β-Enamino esters are useful in synthesis of pharmaceuticals and bioactive heterocycles (Spivey et al., 2003[Spivey, A., Srikaran, C., Diaper, C. & Turner, D. (2003). Org. Biomol. Chem. 1, 1638-1640.]) and as precursors for the preparation of anti­bacterial, anti­convulsant (Michael et al., 2001[Michael, J., Koning, C., Hosken, G. & Stanbury, T. (2001). Tetrahedron, 57, 9635-9648.]), anti-inflamatory and anti­tumour agents. For the functionalization of these compounds by the introduction of different substituents on the nitro­gen, α-carbon and β-carbonylic carbon atoms, see: Braibante et al. (2002[Braibante, H., Costa, C., Martins, D. & Braibante, M. (2002). Tetrahedron Lett. 43, 8079-8081.]).

[Scheme 1]

Experimental

Crystal data

  • C15H21NO2

  • Mr = 247.33

  • Monoclinic, P 21 /c

  • a = 8.5647 (8) Å

  • b = 20.6131 (19) Å

  • c = 8.2404 (8) Å

  • β = 93.976 (2)°

  • V = 1451.3 (2) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.07 mm−1

  • T = 298 K

  • 0.48 × 0.37 × 0.15 mm
Data collection

  • Bruker SMART APEX CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.970, Tmax = 0.989

  • 11717 measured reflections

  • 2634 independent reflections

  • 2160 reflections with I > 2σ(I)

  • Rint = 0.028
Refinement

  • R[F2 > 2σ(F2)] = 0.049

  • wR(F2) = 0.145

  • S = 1.05

  • 2634 reflections

  • 166 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.19 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1⋯O1 0.82 (2) 2.08 (2) 2.7516 (18) 138.7 (17)
N1—H1⋯O1i 0.82 (2) 2.60 (2) 3.2201 (18) 133.1 (16)
Symmetry code: (i) -x+1, -y, -z+1.

Data collection: SMART (Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S160053680903949X/bt5072sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053680903949X/bt5072Isup2.hkl

checkCIF report


Comment top

The enamino esters are gaining increased interest, which are known as important intermediates for the synthesis of natural products (Marchand et al, 1994). The β-enamino esters are useful in synthesis of pharmaceuticals and bioactive heterocycles (Spivey et al., 2003) and as precursors for the preparation of antibacterial, anticonvulsant (Michael et al., 2001), anti-inflamatory and antitumour agents. The functionalization of these compounds by the introduction of different substituents on the nitrogen atom, the α-carbon and β-carbonylic carbon atoms has been studied (Braibante et al., 2002).

The molecular structure and the atomic numbering scheme is shown in Fig. 1. The trimethylyphenyl substituent is almost perpendicular to the β-enaminoester function forming a dihedral angle of 88.10 (6)°.

Related literature top

For enamino esters as intermediates in the synthesis of natural products, see: Marchand et al. (1994). β-Enamino esters are useful in synthesis of pharmaceuticals and bioactive heterocycles (Spivey et al., 2003) and as precursors for the preparation of antibacterial, anticonvulsant (Michael et al., 2001), anti-inflamatory and antitumour agents. For the functionalization of these compounds by the introduction of different substituents on the nitrogen, α-carbon and β-carbonylic carbon atoms, see: Braibante et al. (2002).

Experimental top

A mixture of ethyl acetoacetate (5 mmol), 2,4,6-trimethylaniline (5 mmol) were dispersed on Actisil-FF (1 g, Mexican Bentonitic Clay) and the mixture was stirred at r.t overnight. The product was extracted by washing the clay with CH2Cl2 (3x10mL), dried (Na2SO4), filtred and the solvent was removed in vacuo. The crude product was purified by column chromatography and recrystallized from hexane. Yield: 92%, M.p. 65.4°C

Refinement top

H atom on amine group was found in Fourier map and its coordinates were refined with Uiso(H) = 1.2 Ueq(N). H atoms bonded to C atoms were placed in geometrically idealized positions [C-H = 0.97 Å (for CH2) and 0.96 Å (for CH3)] and refined using a riding model with Uiso(H) = 1.2 Ueq(C) or 1.5 UeqC(methyl).

Structure description top

The enamino esters are gaining increased interest, which are known as important intermediates for the synthesis of natural products (Marchand et al, 1994). The β-enamino esters are useful in synthesis of pharmaceuticals and bioactive heterocycles (Spivey et al., 2003) and as precursors for the preparation of antibacterial, anticonvulsant (Michael et al., 2001), anti-inflamatory and antitumour agents. The functionalization of these compounds by the introduction of different substituents on the nitrogen atom, the α-carbon and β-carbonylic carbon atoms has been studied (Braibante et al., 2002).

The molecular structure and the atomic numbering scheme is shown in Fig. 1. The trimethylyphenyl substituent is almost perpendicular to the β-enaminoester function forming a dihedral angle of 88.10 (6)°.

For enamino esters as intermediates in the synthesis of natural products, see: Marchand et al. (1994). β-Enamino esters are useful in synthesis of pharmaceuticals and bioactive heterocycles (Spivey et al., 2003) and as precursors for the preparation of antibacterial, anticonvulsant (Michael et al., 2001), anti-inflamatory and antitumour agents. For the functionalization of these compounds by the introduction of different substituents on the nitrogen, α-carbon and β-carbonylic carbon atoms, see: Braibante et al. (2002).

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The Molecular structure with the atom numbering scheme. Displacement ellipsoids are drawn at the 40% probability level. H atoms bonded to C omitted. The intramolecular hydrogen bond is shown as a dashed line.
(Z)-Ethyl 3-(2,4,6-trimethylanilino)but-2-enoate top
Crystal data top
C15H21NO2F(000) = 536
Mr = 247.33Dx = 1.132 Mg m−3
Monoclinic, P21/cMelting point: 338.2 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 8.5647 (8) ÅCell parameters from 5426 reflections
b = 20.6131 (19) Åθ = 2.6–25.3°
c = 8.2404 (8) ŵ = 0.07 mm−1
β = 93.976 (2)°T = 298 K
V = 1451.3 (2) Å3Plates, colorless
Z = 40.48 × 0.37 × 0.15 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		2634 independent reflections
Radiation source: fine-focus sealed tube2160 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
Detector resolution: 0.661 pixels mm-1θmax = 25.4°, θmin = 2.0°
ω scansh = −10→10
Absorption correction: multi-scan
(SADABS; Bruker, 1999)		k = −24→24
Tmin = 0.970, Tmax = 0.989l = −9→9
11717 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.145H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.0824P)2 + 0.188P]
where P = (Fo2 + 2Fc2)/3
2634 reflections(Δ/σ)max < 0.001
166 parametersΔρmax = 0.19 e Å−3
0 restraintsΔρmin = −0.21 e Å−3
Crystal data top
C15H21NO2V = 1451.3 (2) Å3
Mr = 247.33Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.5647 (8) ŵ = 0.07 mm−1
b = 20.6131 (19) ÅT = 298 K
c = 8.2404 (8) Å0.48 × 0.37 × 0.15 mm
β = 93.976 (2)°
Data collection top
Bruker SMART APEX CCD
diffractometer		2634 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)		2160 reflections with I > 2σ(I)
Tmin = 0.970, Tmax = 0.989Rint = 0.028
11717 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0490 restraints
wR(F2) = 0.145H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.19 e Å−3
2634 reflectionsΔρmin = −0.21 e Å−3
166 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.34094 (14)0.02629 (6)0.57044 (15)0.0678 (4)
O20.12297 (13)0.06508 (5)0.67115 (14)0.0634 (3)
N10.48468 (17)0.11091 (7)0.36990 (19)0.0608 (4)
H10.475 (2)0.0741 (10)0.407 (2)0.073*
C10.25234 (18)0.07166 (8)0.58833 (18)0.0531 (4)
C20.26799 (18)0.13592 (8)0.5250 (2)0.0572 (4)
H20.19880.16760.55600.069*
C30.37828 (18)0.15303 (8)0.4223 (2)0.0559 (4)
C40.3850 (2)0.22125 (9)0.3585 (3)0.0767 (6)
H4A0.49230.23440.35550.115*
H4B0.33210.24990.42850.115*
H4C0.33490.22300.25070.115*
C50.0901 (2)0.00058 (9)0.7287 (3)0.0746 (5)
H5A0.1642−0.01080.81850.089*
H5B0.0998−0.03070.64210.089*
C6−0.0711 (2)−0.00040 (10)0.7828 (2)0.0733 (5)
H6A−0.0964−0.04350.81640.110*
H6B−0.14330.01280.69460.110*
H6C−0.07820.02890.87250.110*
C70.60799 (18)0.12825 (7)0.27088 (19)0.0520 (4)
C80.58802 (19)0.12037 (8)0.1023 (2)0.0568 (4)
C90.7112 (2)0.13715 (8)0.0097 (2)0.0603 (4)
H90.69840.1328−0.10270.072*
C100.85176 (19)0.16000 (8)0.0787 (2)0.0568 (4)
C110.86788 (19)0.16666 (8)0.2457 (2)0.0577 (4)
H110.96230.18190.29380.069*
C120.74836 (19)0.15143 (7)0.34424 (19)0.0549 (4)
C130.4379 (2)0.09401 (11)0.0225 (3)0.0857 (6)
H13A0.45110.0857−0.09030.129*
H13B0.35560.12510.03190.129*
H13C0.41120.05440.07520.129*
C140.9846 (2)0.17663 (10)−0.0250 (3)0.0794 (6)
H14A1.06100.20210.03750.119*
H14B0.94490.2010−0.11820.119*
H14C1.03220.1374−0.06030.119*
C150.7719 (3)0.15816 (11)0.5262 (2)0.0779 (6)
H15A0.88120.16400.55670.117*
H15B0.73500.11970.57710.117*
H15C0.71460.19510.56080.117*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0634 (7)0.0594 (7)0.0838 (8)0.0124 (6)0.0279 (6)0.0107 (6)
O20.0624 (7)0.0567 (7)0.0746 (7)0.0074 (5)0.0297 (6)0.0078 (5)
N10.0599 (8)0.0490 (8)0.0766 (9)0.0057 (6)0.0279 (7)0.0094 (6)
C10.0497 (8)0.0573 (9)0.0535 (8)0.0036 (7)0.0120 (7)−0.0022 (6)
C20.0530 (9)0.0534 (9)0.0672 (10)0.0071 (7)0.0176 (7)−0.0019 (7)
C30.0543 (9)0.0506 (8)0.0639 (9)0.0035 (7)0.0119 (7)0.0002 (7)
C40.0776 (12)0.0550 (10)0.1014 (14)0.0119 (9)0.0333 (11)0.0115 (9)
C50.0786 (12)0.0627 (11)0.0861 (12)0.0072 (9)0.0319 (10)0.0177 (9)
C60.0698 (12)0.0707 (11)0.0814 (12)−0.0063 (9)0.0192 (9)0.0079 (9)
C70.0514 (9)0.0451 (8)0.0610 (9)0.0051 (6)0.0156 (7)0.0047 (6)
C80.0527 (9)0.0570 (9)0.0610 (9)0.0046 (7)0.0056 (7)−0.0013 (7)
C90.0667 (10)0.0639 (10)0.0510 (8)0.0071 (8)0.0102 (7)0.0015 (7)
C100.0594 (10)0.0492 (8)0.0636 (9)0.0036 (7)0.0186 (7)0.0058 (7)
C110.0534 (9)0.0518 (9)0.0683 (10)−0.0035 (7)0.0079 (7)0.0008 (7)
C120.0610 (10)0.0492 (8)0.0552 (9)0.0056 (7)0.0081 (7)0.0026 (6)
C130.0639 (12)0.1009 (16)0.0914 (14)−0.0044 (10)−0.0012 (10)−0.0153 (12)
C140.0781 (13)0.0738 (12)0.0907 (14)−0.0036 (10)0.0375 (11)0.0090 (10)
C150.0872 (14)0.0882 (14)0.0583 (10)0.0039 (11)0.0061 (9)−0.0009 (9)
Geometric parameters (Å, º) top
O1—C11.2196 (18)C7—C81.397 (2)
O2—C11.3479 (18)C8—C91.388 (2)
O2—C51.446 (2)C8—C131.505 (3)
N1—C31.351 (2)C9—C101.378 (2)
N1—C71.4243 (19)C9—H90.9300
N1—H10.82 (2)C10—C111.380 (2)
C1—C21.433 (2)C10—C141.509 (2)
C2—C31.358 (2)C11—C121.386 (2)
C2—H20.9300C11—H110.9300
C3—C41.504 (2)C12—C151.506 (2)
C4—H4A0.9600C13—H13A0.9600
C4—H4B0.9600C13—H13B0.9600
C4—H4C0.9600C13—H13C0.9600
C5—C61.481 (3)C14—H14A0.9600
C5—H5A0.9700C14—H14B0.9600
C5—H5B0.9700C14—H14C0.9600
C6—H6A0.9600C15—H15A0.9600
C6—H6B0.9600C15—H15B0.9600
C6—H6C0.9600C15—H15C0.9600
C7—C121.392 (2)
C1—O2—C5116.36 (12)C9—C8—C7118.18 (15)
C3—N1—C7124.42 (14)C9—C8—C13120.59 (16)
C3—N1—H1112.7 (13)C7—C8—C13121.23 (16)
C7—N1—H1122.8 (13)C10—C9—C8122.28 (15)
O1—C1—O2121.62 (14)C10—C9—H9118.9
O1—C1—C2126.15 (14)C8—C9—H9118.9
O2—C1—C2112.22 (13)C9—C10—C11117.98 (15)
C3—C2—C1123.61 (14)C9—C10—C14121.04 (16)
C3—C2—H2118.2C11—C10—C14120.98 (17)
C1—C2—H2118.2C10—C11—C12122.32 (15)
N1—C3—C2123.10 (15)C10—C11—H11118.8
N1—C3—C4116.49 (15)C12—C11—H11118.8
C2—C3—C4120.40 (14)C11—C12—C7118.29 (15)
C3—C4—H4A109.5C11—C12—C15120.61 (16)
C3—C4—H4B109.5C7—C12—C15121.08 (15)
H4A—C4—H4B109.5C8—C13—H13A109.5
C3—C4—H4C109.5C8—C13—H13B109.5
H4A—C4—H4C109.5H13A—C13—H13B109.5
H4B—C4—H4C109.5C8—C13—H13C109.5
O2—C5—C6108.55 (15)H13A—C13—H13C109.5
O2—C5—H5A110.0H13B—C13—H13C109.5
C6—C5—H5A110.0C10—C14—H14A109.5
O2—C5—H5B110.0C10—C14—H14B109.5
C6—C5—H5B110.0H14A—C14—H14B109.5
H5A—C5—H5B108.4C10—C14—H14C109.5
C5—C6—H6A109.5H14A—C14—H14C109.5
C5—C6—H6B109.5H14B—C14—H14C109.5
H6A—C6—H6B109.5C12—C15—H15A109.5
C5—C6—H6C109.5C12—C15—H15B109.5
H6A—C6—H6C109.5H15A—C15—H15B109.5
H6B—C6—H6C109.5C12—C15—H15C109.5
C12—C7—C8120.94 (14)H15A—C15—H15C109.5
C12—C7—N1119.32 (14)H15B—C15—H15C109.5
C8—C7—N1119.73 (14)
C5—O2—C1—O1−3.7 (2)N1—C7—C8—C130.2 (2)
C5—O2—C1—C2175.22 (15)C7—C8—C9—C101.2 (2)
O1—C1—C2—C36.4 (3)C13—C8—C9—C10−178.42 (17)
O2—C1—C2—C3−172.41 (15)C8—C9—C10—C11−0.6 (2)
C7—N1—C3—C2−175.71 (16)C8—C9—C10—C14178.82 (16)
C7—N1—C3—C45.4 (3)C9—C10—C11—C12−0.2 (2)
C1—C2—C3—N1−0.1 (3)C14—C10—C11—C12−179.62 (15)
C1—C2—C3—C4178.75 (17)C10—C11—C12—C70.4 (2)
C1—O2—C5—C6−167.50 (15)C10—C11—C12—C15178.79 (16)
C3—N1—C7—C1285.6 (2)C8—C7—C12—C110.1 (2)
C3—N1—C7—C8−95.9 (2)N1—C7—C12—C11178.62 (13)
C12—C7—C8—C9−0.9 (2)C8—C7—C12—C15−178.23 (15)
N1—C7—C8—C9−179.37 (13)N1—C7—C12—C150.2 (2)
C12—C7—C8—C13178.68 (16)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.82 (2)2.08 (2)2.7516 (18)138.7 (17)
N1—H1···O1i0.82 (2)2.60 (2)3.2201 (18)133.1 (16)
Symmetry code: (i) −x+1, −y, −z+1.

Experimental details

Crystal data
Chemical formulaC15H21NO2
Mr247.33
Crystal system, space groupMonoclinic, P21/c
Temperature (K)298
a, b, c (Å)8.5647 (8), 20.6131 (19), 8.2404 (8)
β (°) 93.976 (2)
V (Å3)1451.3 (2)
Z4
Radiation typeMo Kα
µ (mm−1)0.07
Crystal size (mm)0.48 × 0.37 × 0.15
Data collection
DiffractometerBruker SMART APEX CCD
Absorption correctionMulti-scan
(SADABS; Bruker, 1999)
Tmin, Tmax0.970, 0.989
No. of measured, independent and
observed [I > 2σ(I)] reflections		11717, 2634, 2160
Rint0.028
(sin θ/λ)max (Å−1)0.602
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.145, 1.05
No. of reflections2634
No. of parameters166
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.19, −0.21

Computer programs: SMART (Bruker, 1999), SAINT (Bruker, 1999), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.82 (2)2.08 (2)2.7516 (18)138.7 (17)
N1—H1···O1i0.82 (2)2.60 (2)3.2201 (18)133.1 (16)
Symmetry code: (i) −x+1, −y, −z+1.
 

References

First citationBraibante, H., Costa, C., Martins, D. & Braibante, M. (2002). Tetrahedron Lett. 43, 8079–8081.  Web of Science CrossRef CAS Google Scholar
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ISSN: 2056-9890
Volume 65| Part 11| November 2009| Page o2728
https://doi.org/10.1107/S160053680903949X
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