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

Journal logoIUCrDATA
ISSN: 2414-3146

N,1-Bis(4-eth­­oxy­phen­yl)-2,6-di­methyl-4-oxo-1,4-di­hydro­pyridine-3-carboxamide

aUniversity of Mainz, Institute of Organic Chemistry, Duesbergweg 10-14, 55099 Mainz, Germany
*Correspondence e-mail: detert@uni-mainz.de

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 15 November 2018; accepted 19 November 2018; online 22 November 2018)

Condensation of ethyl aceto­acetate and phenetidine gives the title compound, C24H26N2O4. The planar eth­oxy­phenyl group attached to the pyridine ring is twisted about 77.96 (11)° out of the plane of the N-eth­oxy­carboxamido­pyridine unit. The carboxamide unit forms a dihedral angle of about 28.1 (2)° with the pyridine ring.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Two mol­ecules of the title compound (Fig. 1[link]) fill the triclinic unit cell. The compound is composed of three planar rings with an intra­molecular hydrogen bridge N21—H21⋯O17 (Table 1[link]). The amide group is essentially planar [torsion angle O20—C19—N21—C22: 0.6 (3)°] but is twisted [O20—C19—C5—C6: −26.9 (3)°; C19—N21—C22—C27: 27.8 (3)°] out of the plane of the nearly coplanar pyridine and phenyl rings [dihedral angle between the mean planes of the pyridine and phenyl rings: 2.77 (10)°]. On the other hand, the N-phenyl pyridone linkage shows a large torsion angle [C12—C7—N1—C6: 76.0 (3)°]. Both eth­oxy groups are nearly coplanar with the phenyl rings to which they are attached: the angle between the mean planes of the eth­oxy groups and the aromatic ring on the amide side is 6.0 (2)° and on the pyridine side only 5.2 (2)°.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N21—H21⋯O17 0.93 (2) 1.84 (2) 2.636 (2) 142.3 (18)
[Figure 1]
Figure 1
Perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level. The intra­molecular hydrogen bond is drawn with a dashed line.

Synthesis and crystallization

The title compound was isolated as a side product in the formation of p-eth­oxy acetoacetanilide, an inter­mediate in the 4-hy­droxy­quinoline synthesis according to Konrad–Limpach (Eicher & Hauptmann, 1994[Eicher, T. & Hauptmann, S. (1994). Chemie der Heterocyclen, pp. 330-331. Stuttgart: Thieme.]). A mixture of ethyl aceto­acetate (40 ml) was heated in an open flask to 433 K and phenetidine (10 ml) was added slowly. After complete addition of the amine, strirring and heating was continued for 3 h. After cooling to ambient temperature, about 5 ml of diluted hydro­chloric acid was added and the mixture heated for further 3 h. After standing at 255 K for two weeks,the product crystallized as off-white crystals, m.p. = 484 K.

H-NMR (300 MHz; CDCl3): δH = δ [ppm] = 12.57 (s, 1H, N—H), 7.63–7.57 (m, 2H, Ph-2,6-H), 7.10–6.99 (m, 4H, Ph-2,3,5,6-H), 6.88–6.83 (m, 2H, Ph-3,5-H), 6.49 (d, 1H, 4J = 0.88 Hz, 3-H py), 4.09 (q, 2H, 3J = 6.98 Hz, O—CH2–), 4.01 (q, 2H, 3J = 6.96 Hz, O—CH2), 2.53 (s, 3H, CH3, 18-H), 1.93 (d, 3H, 4J = 0.81 Hz, CH3, 16-H), 1.47 (t, 3H, 3J = 6.97 Hz, OEt-CH3), 1.39 (t, 3H, 3J = 6.97 Hz, OEt-CH3); C-NMR (100 MHz; CDCl3) δC (75 MHz, CDCl3): δ [ppm] = 178.11, 164.12, 159.81, 156.85, 155.36, 149.03, 132.31, 132.16, 128.83 (2 C, Ph), 122.34 (2 C, Ph), 119.01, 118.89 (=CH–), 115.95 (2 C, Ph), 114.73 (2 C, Ph), 64.14 (O—CH2–), 63.77 (O—CH2–), 21.93 (CH3, C-16), 20.93 (CH3, C-18), 15.03 (OEt—CH3), 14.85 (OEt—CH3). HR–ESI:[C24H26N2O4 + H]+: calculated: 407.1966; found: 407.1962: IR: 3053, 2982, 2360, 2341, 1665, 1507, 1394, 1265, 1242, 1116, 1042, 825, 733, 703, 568 cm−1.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C24H26N2O4
Mr 406.47
Crystal system, space group Triclinic, P[\overline{1}]
Temperature (K) 193
a, b, c (Å) 8.5516 (5), 11.5937 (7), 11.6637 (8)
α, β, γ (°) 64.268 (4), 79.206 (5), 84.288 (5)
V3) 1023.07 (12)
Z 2
Radiation type Cu Kα
μ (mm−1) 0.73
Crystal size (mm) 0.17 × 0.11 × 0.04
 
Data collection
Diffractometer Stoe IPDS 2T
No. of measured, independent and observed [I > 2σ(I)] reflections 10018, 3512, 2627
Rint 0.020
(sin θ/λ)max−1) 0.599
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.047, 0.133, 1.07
No. of reflections 3512
No. of parameters 280
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.24, −0.22
Computer programs: X-RED and X-AREA (Stoe & Cie, 1996[Stoe & Cie (1996). X-RED and X-AREA. Stoe & Cie, Darmstadt, Germany.]), SIR2004 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]), SHELXL2018 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Structural data


Computing details top

Data collection: X-RED and X-AREA (Stoe & Cie, 1996); cell refinement: X-RED and X-AREA (Stoe & Cie, 1996); data reduction: X-RED and X-AREA (Stoe & Cie, 1996); program(s) used to solve structure: SIR2004 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009).

N,1-Bis(4-ethoxyphenyl)-2,6-dimethyl-4-oxo-1,4-dihydropyridine-3-carboxamide top
Crystal data top
C24H26N2O4Z = 2
Mr = 406.47F(000) = 432
Triclinic, P1Dx = 1.319 Mg m3
a = 8.5516 (5) ÅCu Kα radiation, λ = 1.54178 Å
b = 11.5937 (7) ÅCell parameters from 15045 reflections
c = 11.6637 (8) Åθ = 4.2–68.5°
α = 64.268 (4)°µ = 0.73 mm1
β = 79.206 (5)°T = 193 K
γ = 84.288 (5)°Column, colourless
V = 1023.07 (12) Å30.17 × 0.11 × 0.04 mm
Data collection top
Stoe IPDS 2T
diffractometer
2627 reflections with I > 2σ(I)
Radiation source: Incoatec microSource CuRint = 0.020
Detector resolution: 6.67 pixels mm-1θmax = 67.4°, θmin = 4.2°
rotation method scansh = 1010
10018 measured reflectionsk = 1313
3512 independent reflectionsl = 1312
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.047 w = 1/[σ2(Fo2) + (0.0612P)2 + 0.4717P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.133(Δ/σ)max < 0.001
S = 1.07Δρmax = 0.24 e Å3
3512 reflectionsΔρmin = 0.22 e Å3
280 parametersExtinction correction: SHELXL2018 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0077 (8)
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with isotropic displacement parameters set to 1.2 Ueq(C) or 1.5 Ueq(Cmethyl). The hydrogen atom attached to N21 was localized in difference fourier maps and freely refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.6114 (2)0.24526 (15)0.58878 (15)0.0341 (4)
C20.6827 (2)0.35960 (18)0.50480 (19)0.0356 (5)
C30.6196 (2)0.43617 (19)0.3985 (2)0.0378 (5)
H30.6703480.5145700.3413880.045*
C40.4809 (2)0.40539 (19)0.36765 (19)0.0361 (5)
C50.4176 (2)0.27997 (18)0.45280 (19)0.0335 (5)
C60.4808 (2)0.20510 (19)0.56345 (19)0.0358 (5)
C70.6766 (2)0.16369 (19)0.70529 (19)0.0348 (5)
C80.6408 (3)0.1903 (2)0.8123 (2)0.0398 (5)
H80.5801260.2648020.8083020.048*
C90.6944 (3)0.1071 (2)0.9247 (2)0.0419 (5)
H90.6707030.1246940.9985130.050*
C100.7829 (3)0.00222 (19)0.9311 (2)0.0378 (5)
C110.8215 (3)0.0266 (2)0.8232 (2)0.0400 (5)
H110.8848860.0997120.8262940.048*
C120.7667 (3)0.05662 (19)0.7103 (2)0.0374 (5)
H120.7914260.0398180.6360680.045*
O130.8246 (2)0.07885 (14)1.04879 (14)0.0477 (4)
C140.9102 (3)0.1947 (2)1.0638 (2)0.0496 (6)
H14A1.0156940.1763051.0080200.059*
H14B0.8506970.2479891.0401830.059*
C150.9292 (3)0.2628 (2)1.2037 (2)0.0594 (7)
H15A0.9855240.2078791.2261780.089*
H15B0.9905470.3426861.2184010.089*
H15C0.8240020.2823211.2574520.089*
C160.8280 (3)0.3941 (2)0.5366 (2)0.0435 (5)
H16A0.8699170.4746110.4665890.065*
H16B0.9091500.3259450.5468320.065*
H16C0.8001550.4045060.6170150.065*
O170.42020 (18)0.48431 (13)0.27114 (14)0.0426 (4)
C180.4110 (3)0.0813 (2)0.6649 (2)0.0464 (6)
H18A0.4194550.0743010.7503860.070*
H18B0.4691560.0096030.6520100.070*
H18C0.2986500.0791790.6587920.070*
C190.2854 (3)0.22908 (19)0.42149 (19)0.0365 (5)
O200.26641 (19)0.11429 (13)0.45822 (15)0.0474 (4)
N210.1883 (2)0.32054 (16)0.34782 (17)0.0366 (4)
H210.232 (3)0.401 (2)0.308 (2)0.036 (6)*
C220.0552 (2)0.29886 (19)0.30477 (19)0.0339 (5)
C230.0072 (2)0.39391 (19)0.19478 (19)0.0384 (5)
H230.0670460.4698690.1485390.046*
C240.1265 (3)0.3808 (2)0.1505 (2)0.0403 (5)
H240.1582160.4477810.0752000.048*
C250.2137 (2)0.26991 (19)0.2161 (2)0.0371 (5)
C260.1668 (2)0.17523 (19)0.3272 (2)0.0380 (5)
H260.2273350.0996650.3740360.046*
C270.0346 (2)0.18856 (19)0.3710 (2)0.0371 (5)
H270.0041130.1220270.4470920.044*
O280.34753 (18)0.24578 (14)0.18180 (15)0.0459 (4)
C290.4047 (3)0.3416 (2)0.0713 (2)0.0445 (6)
H29A0.3274210.3535520.0075050.053*
H29B0.4195710.4241710.0783370.053*
C300.5609 (3)0.2979 (2)0.0643 (2)0.0477 (6)
H30A0.5960220.3559390.0172990.071*
H30B0.6407470.2981950.1364240.071*
H30C0.5478050.2109220.0693830.071*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0388 (9)0.0323 (9)0.0310 (9)0.0029 (7)0.0072 (7)0.0122 (7)
C20.0415 (11)0.0308 (10)0.0336 (11)0.0052 (8)0.0036 (9)0.0129 (9)
C30.0413 (12)0.0326 (10)0.0381 (11)0.0049 (9)0.0041 (9)0.0139 (9)
C40.0421 (12)0.0320 (10)0.0331 (11)0.0007 (9)0.0048 (9)0.0132 (9)
C50.0375 (11)0.0300 (10)0.0331 (11)0.0009 (8)0.0067 (9)0.0131 (9)
C60.0412 (12)0.0327 (10)0.0336 (11)0.0032 (9)0.0053 (9)0.0141 (9)
C70.0395 (11)0.0318 (10)0.0317 (11)0.0030 (8)0.0082 (9)0.0107 (9)
C80.0452 (12)0.0383 (11)0.0358 (11)0.0037 (9)0.0070 (9)0.0166 (9)
C90.0517 (13)0.0414 (12)0.0350 (11)0.0048 (10)0.0082 (10)0.0191 (10)
C100.0432 (12)0.0356 (11)0.0330 (11)0.0012 (9)0.0092 (9)0.0118 (9)
C110.0453 (12)0.0360 (11)0.0394 (12)0.0003 (9)0.0067 (10)0.0171 (10)
C120.0435 (12)0.0371 (11)0.0341 (11)0.0019 (9)0.0057 (9)0.0175 (9)
O130.0617 (10)0.0406 (8)0.0379 (8)0.0087 (7)0.0162 (7)0.0126 (7)
C140.0609 (15)0.0351 (11)0.0542 (14)0.0060 (10)0.0234 (12)0.0162 (11)
C150.0764 (18)0.0391 (13)0.0550 (15)0.0018 (12)0.0259 (14)0.0074 (11)
C160.0447 (13)0.0418 (12)0.0429 (12)0.0083 (10)0.0071 (10)0.0152 (10)
O170.0490 (9)0.0327 (8)0.0392 (8)0.0026 (6)0.0129 (7)0.0064 (7)
C180.0524 (14)0.0405 (12)0.0383 (12)0.0118 (10)0.0124 (10)0.0052 (10)
C190.0430 (12)0.0315 (10)0.0337 (11)0.0009 (9)0.0074 (9)0.0121 (9)
O200.0582 (10)0.0300 (8)0.0545 (10)0.0028 (7)0.0234 (8)0.0124 (7)
N210.0394 (10)0.0276 (9)0.0393 (10)0.0016 (7)0.0087 (8)0.0099 (8)
C220.0339 (11)0.0332 (10)0.0341 (11)0.0016 (8)0.0041 (9)0.0148 (9)
C230.0416 (12)0.0334 (11)0.0341 (11)0.0063 (9)0.0049 (9)0.0083 (9)
C240.0462 (12)0.0347 (11)0.0341 (11)0.0003 (9)0.0083 (9)0.0087 (9)
C250.0366 (11)0.0351 (11)0.0384 (11)0.0012 (9)0.0062 (9)0.0146 (9)
C260.0362 (11)0.0315 (10)0.0411 (12)0.0012 (8)0.0054 (9)0.0109 (9)
C270.0394 (11)0.0294 (10)0.0361 (11)0.0005 (8)0.0064 (9)0.0083 (9)
O280.0437 (9)0.0394 (8)0.0479 (9)0.0048 (7)0.0162 (7)0.0082 (7)
C290.0497 (13)0.0392 (11)0.0421 (12)0.0003 (10)0.0152 (10)0.0120 (10)
C300.0430 (13)0.0515 (13)0.0526 (14)0.0028 (10)0.0117 (11)0.0251 (11)
Geometric parameters (Å, º) top
N1—C61.378 (3)C15—H15C0.9800
N1—C21.378 (2)C16—H16A0.9800
N1—C71.455 (2)C16—H16B0.9800
C2—C31.348 (3)C16—H16C0.9800
C2—C161.497 (3)C18—H18A0.9800
C3—C41.421 (3)C18—H18B0.9800
C3—H30.9500C18—H18C0.9800
C4—O171.266 (2)C19—O201.226 (2)
C4—C51.447 (3)C19—N211.362 (3)
C5—C61.380 (3)N21—C221.411 (3)
C5—C191.495 (3)N21—H210.93 (2)
C6—C181.499 (3)C22—C231.381 (3)
C7—C121.379 (3)C22—C271.392 (3)
C7—C81.386 (3)C23—C241.386 (3)
C8—C91.377 (3)C23—H230.9500
C8—H80.9500C24—C251.385 (3)
C9—C101.390 (3)C24—H240.9500
C9—H90.9500C25—O281.371 (3)
C10—O131.364 (2)C25—C261.385 (3)
C10—C111.382 (3)C26—C271.372 (3)
C11—C121.386 (3)C26—H260.9500
C11—H110.9500C27—H270.9500
C12—H120.9500O28—C291.421 (2)
O13—C141.421 (3)C29—C301.503 (3)
C14—C151.506 (3)C29—H29A0.9900
C14—H14A0.9900C29—H29B0.9900
C14—H14B0.9900C30—H30A0.9800
C15—H15A0.9800C30—H30B0.9800
C15—H15B0.9800C30—H30C0.9800
C6—N1—C2121.30 (17)C2—C16—H16A109.5
C6—N1—C7119.08 (16)C2—C16—H16B109.5
C2—N1—C7119.62 (17)H16A—C16—H16B109.5
C3—C2—N1119.37 (19)C2—C16—H16C109.5
C3—C2—C16122.52 (18)H16A—C16—H16C109.5
N1—C2—C16118.11 (18)H16B—C16—H16C109.5
C2—C3—C4123.21 (19)C6—C18—H18A109.5
C2—C3—H3118.4C6—C18—H18B109.5
C4—C3—H3118.4H18A—C18—H18B109.5
O17—C4—C3120.80 (19)C6—C18—H18C109.5
O17—C4—C5123.77 (19)H18A—C18—H18C109.5
C3—C4—C5115.44 (18)H18B—C18—H18C109.5
C6—C5—C4120.07 (19)O20—C19—N21122.6 (2)
C6—C5—C19119.21 (17)O20—C19—C5122.82 (18)
C4—C5—C19120.72 (17)N21—C19—C5114.62 (17)
N1—C6—C5120.25 (18)C19—N21—C22126.21 (18)
N1—C6—C18115.91 (18)C19—N21—H21113.0 (13)
C5—C6—C18123.79 (19)C22—N21—H21118.8 (13)
C12—C7—C8120.58 (19)C23—C22—C27118.25 (19)
C12—C7—N1119.52 (19)C23—C22—N21118.56 (18)
C8—C7—N1119.81 (18)C27—C22—N21123.13 (18)
C9—C8—C7119.1 (2)C22—C23—C24121.41 (19)
C9—C8—H8120.5C22—C23—H23119.3
C7—C8—H8120.5C24—C23—H23119.3
C8—C9—C10120.7 (2)C25—C24—C23119.87 (19)
C8—C9—H9119.7C25—C24—H24120.1
C10—C9—H9119.7C23—C24—H24120.1
O13—C10—C11124.96 (19)O28—C25—C24125.27 (19)
O13—C10—C9115.05 (19)O28—C25—C26115.94 (18)
C11—C10—C9120.00 (19)C24—C25—C26118.8 (2)
C10—C11—C12119.3 (2)C27—C26—C25121.21 (19)
C10—C11—H11120.3C27—C26—H26119.4
C12—C11—H11120.3C25—C26—H26119.4
C7—C12—C11120.3 (2)C26—C27—C22120.47 (19)
C7—C12—H12119.8C26—C27—H27119.8
C11—C12—H12119.8C22—C27—H27119.8
C10—O13—C14118.15 (18)C25—O28—C29118.43 (16)
O13—C14—C15106.4 (2)O28—C29—C30107.59 (18)
O13—C14—H14A110.4O28—C29—H29A110.2
C15—C14—H14A110.4C30—C29—H29A110.2
O13—C14—H14B110.4O28—C29—H29B110.2
C15—C14—H14B110.4C30—C29—H29B110.2
H14A—C14—H14B108.6H29A—C29—H29B108.5
C14—C15—H15A109.5C29—C30—H30A109.5
C14—C15—H15B109.5C29—C30—H30B109.5
H15A—C15—H15B109.5H30A—C30—H30B109.5
C14—C15—H15C109.5C29—C30—H30C109.5
H15A—C15—H15C109.5H30A—C30—H30C109.5
H15B—C15—H15C109.5H30B—C30—H30C109.5
C6—N1—C2—C32.8 (3)O13—C10—C11—C12177.6 (2)
C7—N1—C2—C3178.49 (19)C9—C10—C11—C122.1 (3)
C6—N1—C2—C16177.64 (19)C8—C7—C12—C110.6 (3)
C7—N1—C2—C161.1 (3)N1—C7—C12—C11175.92 (19)
N1—C2—C3—C40.2 (3)C10—C11—C12—C70.9 (3)
C16—C2—C3—C4179.4 (2)C11—C10—O13—C141.9 (3)
C2—C3—C4—O17175.3 (2)C9—C10—O13—C14177.8 (2)
C2—C3—C4—C55.0 (3)C10—O13—C14—C15176.1 (2)
O17—C4—C5—C6173.2 (2)C6—C5—C19—O2026.9 (3)
C3—C4—C5—C67.1 (3)C4—C5—C19—O20152.3 (2)
O17—C4—C5—C197.7 (3)C6—C5—C19—N21153.68 (19)
C3—C4—C5—C19171.97 (19)C4—C5—C19—N2127.2 (3)
C2—N1—C6—C50.5 (3)O20—C19—N21—C220.6 (3)
C7—N1—C6—C5179.22 (18)C5—C19—N21—C22179.97 (18)
C2—N1—C6—C18177.83 (19)C19—N21—C22—C23155.2 (2)
C7—N1—C6—C183.5 (3)C19—N21—C22—C2727.8 (3)
C4—C5—C6—N14.6 (3)C27—C22—C23—C240.1 (3)
C19—C5—C6—N1174.49 (18)N21—C22—C23—C24177.27 (19)
C4—C5—C6—C18172.5 (2)C22—C23—C24—C250.8 (3)
C19—C5—C6—C188.4 (3)C23—C24—C25—O28180.0 (2)
C6—N1—C7—C1276.0 (3)C23—C24—C25—C261.6 (3)
C2—N1—C7—C12102.7 (2)O28—C25—C26—C27179.93 (19)
C6—N1—C7—C8100.6 (2)C24—C25—C26—C271.5 (3)
C2—N1—C7—C880.7 (2)C25—C26—C27—C220.6 (3)
C12—C7—C8—C91.0 (3)C23—C22—C27—C260.2 (3)
N1—C7—C8—C9175.53 (19)N21—C22—C27—C26177.24 (19)
C7—C8—C9—C100.2 (3)C24—C25—O28—C290.8 (3)
C8—C9—C10—O13178.0 (2)C26—C25—O28—C29177.67 (19)
C8—C9—C10—C111.7 (3)C25—O28—C29—C30173.54 (18)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N21—H21···O170.93 (2)1.84 (2)2.636 (2)142.3 (18)
 

References

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First citationEicher, T. & Hauptmann, S. (1994). Chemie der Heterocyclen, pp. 330–331. Stuttgart: Thieme.  Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationStoe & Cie (1996). X-RED and X-AREA. Stoe & Cie, Darmstadt, Germany.  Google Scholar

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