Diethyl 4-(4-acetamido­phenyl)-2,6-dimethyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate

Yiliang Zhao; David E Hibbs; Paul W Groundwater; Abram Wassef

doi:10.1107/S160053681202750X

. 2012 Jul 25;68(Pt 8):o2536. doi: 10.1107/S160053681202750X

Diethyl 4-(4-acetamidophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate

Yiliang Zhao ^a,^*, David E Hibbs ^a, Paul W Groundwater ^a, Abram Wassef ^a

PMCID: PMC3414982 PMID: 22904969

Abstract

The title compound, C₂₁H₂₆N₂O₅, was unexpectedly obtained as a by-product in the reaction of ethyl acetoacetate, 4-acetamidobenzaldehyde and urea under microwave irradiation. The dihydropyridine ring assumes a flattened boat conformation. Intermolecular N—H⋯O and weak C—H⋯O hydrogen bonding occurs in the crystal.

Related literature

For the Biginelli dihydropyrimidone and Hantzsch dihydropyridine syntheses, see: Kappe & Stadler (2004 ▶); Kumar & Maurya (2008 ▶). For the microwave synthesis and melting point of 4-(3-acetamidophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate, see: Mobinikhaledi & Foroughifar (2006 ▶).

Experimental

Crystal data

C₂₁H₂₆N₂O₅
M _r = 386.44
Monoclinic,
a = 11.3359 (7) Å
b = 12.1934 (7) Å
c = 15.3262 (9) Å
β = 109.745 (1)°
V = 1993.9 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 K
0.2 × 0.2 × 0.15 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.976, T _max = 0.988
15313 measured reflections
4593 independent reflections
3602 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.120
S = 1.05
4593 reflections
266 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▶); software used to prepare material for publication: OLEX2.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681202750X/xu5556sup1.cif

e-68-o2536-sup1.cif^{(27.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681202750X/xu5556Isup2.hkl

e-68-o2536-Isup2.hkl^{(225KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681202750X/xu5556Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O5ⁱ	0.892 (19)	2.022 (19)	2.8946 (17)	165.5 (16)
N2—H2⋯O3ⁱⁱ	0.866 (19)	2.074 (19)	2.9383 (17)	175.4 (16)
C6—H6A⋯O1ⁱⁱⁱ	0.98	2.52	3.370 (2)	145
C13—H13A⋯O1^iv	0.98	2.38	3.337 (2)	165

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

The authors would like to thank the Clive and Vera Ramaciotti Foundation for a generous equipment gift, and the National Health and Medical Research Council for funding.

supplementary crystallographic information

Comment

The bond lengths and angles in the title compound are as expected. The maximum deviation from the mean plane of the central ring is 0.188 (1) A for C1. The C8 and C11 carboxylate side chains are essentially planar, with a maximum deviation of 0.077 A for C10. These groups are set at 11.64 (8)° and 25.65 (4)° to the central ring plane respectively.

Experimental

A mixture of 4-acetamidobenzaldehyde (163 mg, 1 mmol), ethyl acetoacetate (130 mg, 1 mmol) and urea (60 mg, 1 mmol) was stirred for 2 h at 403 K under microwave irradiation. After completion of the reaction, TLC showed the presence of two main products, which were separated using silica chromatography, eluting with dichloromthane/methanol to give diethyl 4-acetamidophenyl-1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (120 mg, 31%, mp 254–256°C), and ethyl 4-(3-acetamidophenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (72 mg, 23%, mp 284–286°C).