Diethyl 2,6-dimethyl­pyridine-3,5-dicarboxyl­ate

Cui, J.-Z.; Zhang, H.; Zhang, D.; Wang, H.-T.; Gao, H.-L.

doi:10.1107/S1600536805039590

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Diethyl 2,6-dimethylpyridine-3,5-dicarboxylate

J.-Z. Cui, H. Zhang, D. Zhang, H.-T. Wang and H.-L. Gao

The molecular structure of the title compound, C₁₃H₁₇NO₄, has no symmetry plane because one C atom of the ethyl group lies out of the plane defined by the other non-H atoms. In the crystal structure, the molecules stack along the a axis. Symmetry-related molecules are linked by a C—H

O hydrogen bond, forming zigzag chains extending in the b-axis direction.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805039590/su6246sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536805039590/su6246Isup2.hkl Contains datablock I

CCDC reference: 296674

checkCIF report

Key indicators

Single-crystal X-ray study
T = 294 K
Mean (C-C) = 0.004 Å
Disorder in main residue
R factor = 0.049
wR factor = 0.155
Data-to-parameter ratio = 13.0

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        C12

Alert level C
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         48 Perc.
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.70 Ratio
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.22 Ratio
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C8
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C9'
PLAT301_ALERT_3_C Main Residue  Disorder .........................      10.00 Perc.
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          2
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      19.90 Deg.
              C9'  -O2   -C9      1.555   1.555   1.555

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   8 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   5 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

Dihydropyridine compounds are calcium ion channel blockers and the use of these compounds is generally beneficial (Böcker et al., 1986). Aromatization of Hantzsch 1,4-dihydropyridines (1,4-DHP) has attracted considerable attention in recent years, essentially since the discovery that the metabolism of these drugs involves an oxidation step (Eynde et al.,1995). Here we describe the synthesis (Lu et al., 2001) and crystal structure of the title compound, (I).

The molecular structure of the compound (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. A l l of the non-H atoms in (I) lie almost in the same plane, except atom C10 which is out of the plane with a C8—O2—C9—C10 torsion angle of 123.2 (17)°. This is probably because of the disorder of the ethyl group, and for this reason the molecule has no symmetry plane.

In the crystal structure of (I), the molecules stack along the a axis and are linked by C—H···O hydrogen bonds, forming polymer chains extending in the b-axis direction (see Table 2 and Fig. 2 for details).

Experimental top

The title compound, (I) was prepared according to the literature procedure of Lu et al. (2001). A mixture of diethyl 2,6-dimethyl-1,4- dihydropyridine-3,5-dicarboxylate, ferric chloride hexahydrate, acetic acid and water was heated at reflux for 1 h. After neutralization with an aqueous solution of sodium bicarbornate and extraction with chloroform, the title compound was obtained (yield 52%; m.p. 343–344 K). Single crystals, suitable for X-ray diffraction analysis, were obtained by slow evaporation of an ethanol solution. IR (KBr, ν cm⁻¹): 2979, 2932, 1721, 1591, 1442, 1367, 1296, 1223, 1120, 1043, 771, 698.

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; 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.

Figures top

	Fig. 1. The molecular structure of compound (I), showing the atom-labelling scheme, with displacement ellipsolids drawn at the 35% probability level. Only the major component of the disordered ethyl group is shown.
	Fig. 2. The crystal packing of compound (I), viewed along the a axis. Only the major component of the disordered ethyl group is shown. The C—H···O hydrogen bonds are shown as dashed lines.

Diethyl 2,6-dimethylpyridine-3,5-dicarboxylate top

Crystal data top

C₁₃H₁₇NO₄	F(000) = 536
M_r = 251.28	D_x = 1.212 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 343 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 4.593 (2) Å	Cell parameters from 1328 reflections
b = 15.950 (9) Å	θ = 2.5–23.6°
c = 18.795 (10) Å	µ = 0.09 mm⁻¹
β = 90.656 (9)°	T = 294 K
V = 1376.9 (13) Å³	Block, colorless
Z = 4	0.24 × 0.20 × 0.16 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2427 independent reflections
Radiation source: fine-focus sealed tube	1158 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.046
ϕ and ω scans	θ_max = 25.0°, θ_min = 1.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −4→5
T_min = 0.960, T_max = 0.986	k = −18→12
6854 measured reflections	l = −22→22

Refinement top

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.155	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0658P)² + 0.2484P] where P = (F_o² + 2F_c²)/3
2427 reflections	(Δ/σ)_max = 0.002
187 parameters	Δρ_max = 0.20 e Å⁻³
29 restraints	Δρ_min = −0.14 e Å⁻³

Crystal data top

C₁₃H₁₇NO₄	V = 1376.9 (13) Å³
M_r = 251.28	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 4.593 (2) Å	µ = 0.09 mm⁻¹
b = 15.950 (9) Å	T = 294 K
c = 18.795 (10) Å	0.24 × 0.20 × 0.16 mm
β = 90.656 (9)°

Data collection top

Bruker SMART CCD area-detector diffractometer	2427 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1158 reflections with I > 2σ(I)
T_min = 0.960, T_max = 0.986	R_int = 0.046
6854 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	29 restraints
wR(F²) = 0.155	H-atom parameters constrained
S = 1.00	Δρ_max = 0.20 e Å⁻³
2427 reflections	Δρ_min = −0.14 e Å⁻³
187 parameters

Special details top

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
O1	1.2765 (6)	1.00909 (17)	0.29361 (13)	0.1091 (9)
O2	1.0690 (5)	0.93288 (15)	0.20975 (12)	0.0925 (8)
O3	0.3313 (5)	0.65999 (15)	0.35320 (11)	0.0827 (7)
O4	0.4211 (4)	0.71868 (12)	0.24860 (11)	0.0664 (6)
N1	0.9495 (5)	0.83212 (18)	0.44323 (13)	0.0661 (7)
C1	1.0658 (6)	0.8888 (2)	0.39946 (17)	0.0604 (8)
C2	0.9964 (5)	0.88958 (18)	0.32672 (15)	0.0529 (7)
C3	0.7966 (5)	0.83108 (18)	0.30156 (14)	0.0522 (7)
H3	0.7449	0.8310	0.2536	0.063*
C4	0.6733 (5)	0.77302 (17)	0.34672 (14)	0.0500 (7)
C5	0.7594 (6)	0.7747 (2)	0.41872 (15)	0.0611 (8)
C6	1.2721 (7)	0.9495 (2)	0.43497 (17)	0.0836 (11)
H6A	1.1845	1.0041	0.4363	0.125*
H6B	1.4497	0.9521	0.4086	0.125*
H6C	1.3136	0.9310	0.4826	0.125*
C7	0.6517 (8)	0.7147 (2)	0.47389 (16)	0.0934 (12)
H7A	0.7351	0.7289	0.5194	0.140*
H7B	0.7076	0.6586	0.4614	0.140*
H7C	0.4433	0.7180	0.4763	0.140*
C8	1.1295 (7)	0.9500 (2)	0.27714 (18)	0.0662 (8)
C9	1.126 (4)	0.9914 (10)	0.1507 (9)	0.090 (6)	0.39 (2)
H9A	1.2256	1.0415	0.1675	0.108*	0.39 (2)
H9B	0.9473	1.0075	0.1265	0.108*	0.39 (2)
C10	1.321 (5)	0.9396 (10)	0.1025 (8)	0.114 (6)	0.39 (2)
H10A	1.4833	0.9184	0.1295	0.171*	0.39 (2)
H10B	1.3903	0.9741	0.0644	0.171*	0.39 (2)
H10C	1.2112	0.8935	0.0830	0.171*	0.39 (2)
C9'	1.229 (3)	0.9867 (7)	0.1600 (4)	0.084 (3)	0.61 (2)
H9'1	1.4378	0.9824	0.1682	0.100*	0.61 (2)
H9'2	1.1710	1.0448	0.1646	0.100*	0.61 (2)
C10'	1.145 (4)	0.9524 (8)	0.0878 (3)	0.119 (4)	0.61 (2)
H10D	1.2066	0.8950	0.0844	0.178*	0.61 (2)
H10E	1.2384	0.9848	0.0515	0.178*	0.61 (2)
H10F	0.9381	0.9556	0.0816	0.178*	0.61 (2)
C11	0.4586 (6)	0.71134 (19)	0.31846 (16)	0.0554 (7)
C12	0.2205 (6)	0.6604 (2)	0.21440 (16)	0.0700 (9)
H12A	0.0285	0.6654	0.2349	0.084*
H12B	0.2879	0.6032	0.2208	0.084*
C13	0.2095 (10)	0.6817 (3)	0.13845 (18)	0.1354 (18)
H13A	0.1485	0.7389	0.1329	0.203*
H13B	0.0736	0.6454	0.1144	0.203*
H13C	0.3992	0.6747	0.1184	0.203*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.118 (2)	0.0879 (19)	0.121 (2)	−0.0455 (17)	−0.0152 (17)	0.0054 (16)
O2	0.122 (2)	0.0816 (17)	0.0740 (16)	−0.0377 (15)	0.0253 (14)	0.0011 (13)
O3	0.0925 (16)	0.0773 (16)	0.0786 (15)	−0.0218 (13)	0.0083 (12)	0.0090 (13)
O4	0.0680 (13)	0.0658 (14)	0.0653 (13)	−0.0154 (11)	−0.0060 (10)	−0.0022 (11)
N1	0.0579 (15)	0.0766 (19)	0.0637 (16)	0.0063 (15)	−0.0078 (13)	−0.0050 (15)
C1	0.0455 (16)	0.063 (2)	0.072 (2)	0.0135 (16)	−0.0071 (15)	−0.0170 (18)
C2	0.0418 (15)	0.0491 (18)	0.068 (2)	0.0066 (14)	0.0023 (14)	−0.0030 (16)
C3	0.0454 (15)	0.0553 (18)	0.0560 (17)	0.0093 (15)	0.0026 (13)	−0.0044 (15)
C4	0.0424 (14)	0.0507 (18)	0.0569 (17)	0.0064 (14)	0.0035 (13)	−0.0031 (15)
C5	0.0544 (17)	0.067 (2)	0.062 (2)	0.0136 (17)	0.0015 (15)	−0.0007 (17)
C6	0.069 (2)	0.089 (3)	0.093 (2)	−0.002 (2)	−0.0165 (18)	−0.032 (2)
C7	0.107 (3)	0.110 (3)	0.063 (2)	−0.013 (2)	−0.0012 (19)	0.019 (2)
C8	0.0581 (19)	0.056 (2)	0.084 (2)	0.0019 (17)	0.0035 (17)	−0.0088 (19)
C9	0.081 (8)	0.092 (8)	0.098 (9)	−0.029 (7)	0.008 (6)	0.008 (6)
C10	0.115 (9)	0.116 (8)	0.112 (8)	0.007 (7)	0.034 (7)	0.006 (7)
C9'	0.090 (6)	0.077 (5)	0.084 (5)	−0.016 (5)	0.019 (4)	0.008 (4)
C10'	0.148 (8)	0.121 (7)	0.088 (5)	−0.027 (6)	0.019 (5)	0.018 (5)
C11	0.0520 (17)	0.0531 (19)	0.061 (2)	0.0084 (15)	0.0055 (15)	0.0030 (16)
C12	0.0620 (18)	0.065 (2)	0.083 (2)	−0.0094 (17)	−0.0056 (16)	−0.0150 (18)
C13	0.169 (4)	0.155 (4)	0.081 (3)	−0.071 (4)	−0.042 (3)	0.005 (3)

Geometric parameters (Å, º) top

O1—C8	1.198 (3)	C7—H7A	0.9600
O2—C8	1.322 (3)	C7—H7B	0.9600
O2—C9'	1.473 (7)	C7—H7C	0.9600
O2—C9	1.476 (9)	C9—C10	1.525 (10)
O3—C11	1.203 (3)	C9—H9A	0.9700
O4—C11	1.328 (3)	C9—H9B	0.9700
O4—C12	1.454 (3)	C10—H10A	0.9600
N1—C1	1.338 (4)	C10—H10B	0.9600
N1—C5	1.344 (4)	C10—H10C	0.9600
C1—C2	1.400 (4)	C9'—C10'	1.508 (8)
C1—C6	1.505 (4)	C9'—H9'1	0.9700
C2—C3	1.388 (4)	C9'—H9'2	0.9700
C2—C8	1.478 (4)	C10'—H10D	0.9600
C3—C4	1.382 (4)	C10'—H10E	0.9600
C3—H3	0.9300	C10'—H10F	0.9600
C4—C5	1.406 (4)	C12—C13	1.468 (4)
C4—C11	1.487 (4)	C12—H12A	0.9700
C5—C7	1.499 (4)	C12—H12B	0.9700
C6—H6A	0.9600	C13—H13A	0.9600
C6—H6B	0.9600	C13—H13B	0.9600
C6—H6C	0.9600	C13—H13C	0.9600

C8—O2—C9'	112.8 (4)	O2—C8—C2	112.7 (3)
C8—O2—C9	123.5 (10)	O2—C9—C10	102.4 (8)
C9'—O2—C9	19.9 (9)	O2—C9—H9A	111.3
C11—O4—C12	117.1 (2)	C10—C9—H9A	111.3
C1—N1—C5	120.8 (3)	O2—C9—H9B	111.3
N1—C1—C2	121.2 (3)	C10—C9—H9B	111.3
N1—C1—C6	114.6 (3)	H9A—C9—H9B	109.2
C2—C1—C6	124.2 (3)	O2—C9'—C10'	103.6 (6)
C3—C2—C1	118.0 (3)	O2—C9'—H9'1	111.0
C3—C2—C8	120.0 (3)	C10'—C9'—H9'1	111.0
C1—C2—C8	122.0 (3)	O2—C9'—H9'2	111.0
C4—C3—C2	121.0 (3)	C10'—C9'—H9'2	111.0
C4—C3—H3	119.5	H9'1—C9'—H9'2	109.0
C2—C3—H3	119.5	C9'—C10'—H10D	109.5
C3—C4—C5	117.8 (3)	C9'—C10'—H10E	109.5
C3—C4—C11	119.9 (3)	H10D—C10'—H10E	109.5
C5—C4—C11	122.3 (3)	C9'—C10'—H10F	109.5
N1—C5—C4	121.2 (3)	H10D—C10'—H10F	109.5
N1—C5—C7	114.6 (3)	H10E—C10'—H10F	109.5
C4—C5—C7	124.2 (3)	O3—C11—O4	122.6 (3)
C1—C6—H6A	109.5	O3—C11—C4	125.5 (3)
C1—C6—H6B	109.5	O4—C11—C4	111.9 (3)
H6A—C6—H6B	109.5	O4—C12—C13	107.3 (3)
C1—C6—H6C	109.5	O4—C12—H12A	110.3
H6A—C6—H6C	109.5	C13—C12—H12A	110.3
H6B—C6—H6C	109.5	O4—C12—H12B	110.3
C5—C7—H7A	109.5	C13—C12—H12B	110.3
C5—C7—H7B	109.5	H12A—C12—H12B	108.5
H7A—C7—H7B	109.5	C12—C13—H13A	109.5
C5—C7—H7C	109.5	C12—C13—H13B	109.5
H7A—C7—H7C	109.5	H13A—C13—H13B	109.5
H7B—C7—H7C	109.5	C12—C13—H13C	109.5
O1—C8—O2	121.4 (3)	H13A—C13—H13C	109.5
O1—C8—C2	125.9 (3)	H13B—C13—H13C	109.5

C5—N1—C1—C2	−0.8 (4)	C9'—O2—C8—C2	−173.1 (7)
C5—N1—C1—C6	179.3 (2)	C9—O2—C8—C2	167.9 (8)
N1—C1—C2—C3	1.8 (4)	C3—C2—C8—O1	170.6 (3)
C6—C1—C2—C3	−178.4 (3)	C1—C2—C8—O1	−9.6 (5)
N1—C1—C2—C8	−178.1 (3)	C3—C2—C8—O2	−9.1 (4)
C6—C1—C2—C8	1.8 (4)	C1—C2—C8—O2	170.7 (3)
C1—C2—C3—C4	−1.0 (4)	C8—O2—C9—C10	123.2 (17)
C8—C2—C3—C4	178.8 (2)	C9'—O2—C9—C10	61 (2)
C2—C3—C4—C5	−0.7 (4)	C8—O2—C9'—C10'	176.0 (12)
C2—C3—C4—C11	179.7 (2)	C9—O2—C9'—C10'	−57 (2)
C1—N1—C5—C4	−1.0 (4)	C12—O4—C11—O3	−1.1 (4)
C1—N1—C5—C7	179.1 (3)	C12—O4—C11—C4	178.7 (2)
C3—C4—C5—N1	1.7 (4)	C3—C4—C11—O3	−177.5 (3)
C11—C4—C5—N1	−178.6 (2)	C5—C4—C11—O3	2.9 (4)
C3—C4—C5—C7	−178.4 (3)	C3—C4—C11—O4	2.8 (3)
C11—C4—C5—C7	1.2 (4)	C5—C4—C11—O4	−176.9 (2)
C9'—O2—C8—O1	7.2 (8)	C11—O4—C12—C13	178.7 (3)
C9—O2—C8—O1	−11.8 (9)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12B···O1ⁱ	0.97	2.52	3.346 (4)	143

Symmetry code: (i) −x+2, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₁₃H₁₇NO₄
M_r	251.28
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	294
a, b, c (Å)	4.593 (2), 15.950 (9), 18.795 (10)
β (°)	90.656 (9)
V (Å³)	1376.9 (13)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.24 × 0.20 × 0.16

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.960, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	6854, 2427, 1158
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.155, 1.00
No. of reflections	2427
No. of parameters	187
No. of restraints	29
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.14

Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1997), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.

Selected torsion angles (º) top

C8—O2—C9—C10

123.2 (17)

C11—O4—C12—C13

178.7 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12B···O1ⁱ	0.97	2.52	3.346 (4)	143

Symmetry code: (i) −x+2, y−1/2, −z+1/2.

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