Formic acid: A low-cost, mild, ecofriendly, and highly efficient catalyst for the rapid synthesis of β-enaminones

Article abstract of DOI:10.1080/00397911.2012.708467

β-Enaminones have been synthesized by the condensation reaction of b-diketones with various anilines in the presence of a catalytic amount of formic acid, mild and highly efficient acid catalyst in methanol. These condensation reactions proceed smoothly in short reaction times with near-quantitative yields. Copyright

Full text of DOI:10.1080/00397911.2012.708467

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Formic Acid: A Low-Cost, Mild, Ecofriendly and
Highly Efficient Catalyst for the Rapid Synthesis of β-
Enaminones
Siddappa A. Patil a , Phillip A. Medina a , Diego Gonzalez-Flores b , Jason K. Vohs c , Seth
Dever a , Leslie W. Pineda b , Mavis L Montero b & Bradley D. Fahlman a
a Department of Chemistry and Science of Advanced Materials Program, Central Michigan
University, Mount Pleasant, MI, USA
b Centro de Electroquímica y Energía Química (CELEQ); Escuela de Química, Universidad de
Costa Rica, San José, Costa Rica
c Department of Chemistry, Saint Vincent College, Latrobe, PA, USA
Accepted author version posted online: 20 Mar 2013.
To cite this article: Siddappa A. Patil , Phillip A. Medina , Diego Gonzalez-Flores , Jason K. Vohs , Seth Dever , Leslie
W. Pineda , Mavis L Montero & Bradley D. Fahlman (2013): Formic Acid: A Low-Cost, Mild, Ecofriendly and Highly
Efficient Catalyst for the Rapid Synthesis of β-Enaminones, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, DOI:10.1080/00397911.2012.708467
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Formic Acid: A Low-Cost, Mild, Ecofriendly and Highly Efficient Catalyst for the
Rapid Synthesis of β-Enaminones
Siddappa A. Patil1, Phillip A. Medina1, Diego Gonzalez-Flores2, Jason K. Vohs3, Seth
Dever1, Leslie W. Pineda2, Mavis L.Montero2, Bradley D. Fahlman1,
1Department of Chemistry and Science of Advanced Materials Program, Central
Michigan University, Mount Pleasant, MI, USA, 2Centro de Electroquímica y Energía
Química (CELEQ); Escuela de Química, Universidad de Costa Rica, San José, Costa
Rica, 3Department of Chemistry, Saint Vincent College, Latrobe, PA, USA
, , phone: 989-774-1195; fax: 989-774-3883, E-mail: fahlm1b@cmich.edu
Abstract
β-Enaminones have been synthesized by the condensation reaction of β-diketones with
various anilines in the presence of a catalytic amount of formic acid, a mild and ahighly
efficient acid catalyst in methanol. These condensation reactionsproceed smoothly in
short reaction times withnear-quantitative yields.
Supplemental materials are available for this article. Go to the publisher’s online edition
of Synthetic Communications® to view the free supplemental file.
KEYWORDS: β-enaminone; formic acid; synthesis; crystal structure
INTRODUCTION
β-Enaminones have been widely used as key precursors in organic synthesis,[1–3] as well
as synthons for different important heterocycles,[4–6] antibacterial,[7] anticonvulsant, anti-
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inflammatory,[8] or antitumour agents,[9] and naturally occurring alkaloids.[10] Therefore,
development of new synthetic methods has received considerable attention. In 1961,
Martin[11] reported one of the most important ways to prepare β-enaminones, via the
direct condensation of β-dicarbonyl compounds with amines in a refluxing aromatic
solvent. In recent years, this reaction was investigated in depth and detail, mainly
focusing on improving the reaction conditions. This has led to the development of
[13]
interesting reaction systems, such as those catalyzed by K-10 clay,[12] NaAuCl4,
Zn(ClO4)2•6H2O,[14] ionic liquids,[15] CeCl3•7H2O,[16] ZrCl4,[17] ytterbium triflate,[18]
KHSO4 and SiO2.[19] Nevertheless, the application of these systems suffers from one or
more disadvantages, such as using expensive or less readily available reagents, toxic
solvents, drastic reaction conditions, long reaction times, unsatisfactory yields and/or low
selectivity. Therefore, the development of facile and green synthetic methods is still in
high demand.
Formic acid (HCOOH), a major product formed during biomass processing, is widely
used as acid catalyst in organic synthesis since it is relatively inexpensive, and merits
high volatility and easy work-up. Accordingly, it has emerged as a key replacement for
conventional acidic catalysts in organic synthesis. Here in this paper, we report the
synthesis and spectroscopic characterization of variousβ-enaminones derived from 1:1
condensation of β-diketones with various anilinesusing formic acid as a catalyst. In
addition, the crystal structure of one of these compounds, (Z)-4-(4-
methoxyphenylamino)pent-3-en-2-one is presented.
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RESULTS AND DISCUSSION
To optimize the reaction conditions, we carried out the condensation of acetylacetone
with aniline. To study the effect of different heterogeneous catalysts, the reaction was
carried out in methanol at 85 °C in the presence of different acids catalysts (Table 1). The
reaction was catalyzed by all the acid catalysts; however, formic acid was found to be the
best. In order to understand the effect of solvents, the condensation reaction of
acetylacetone with aniline was performed in CHCl3, CHCl2, CH3OH, CH3CH2OH,
C6H5CH3, and C6H6, generatingrespective yields of 54%, 55%, 98%, 87%, 70%, and 76%
(Table 2). Hence, methanol represents the best solvent for our reaction system relative to
theother possible options. To evaluate the effect of amount of catalyst, 0.5, 1.0, and 2.0
mol% formic acid were used for the reaction, with 1.0 mol% formic acid the best choice.
The condensation reaction of acetylacetone with aniline was conducted under the above
optimized conditions at 25 °C for 4 hrs. A new product, (Z)-4-(phenylamino)pent-3-en-
one (3a), was detected by TLC,and isolated in 20% yield. To shorten the reaction time
and increase the yield, the same reaction was carried out at different temperatures, and it
was found that the reaction worked better at 85 °C. Further increases of temperature did
not improve the yield. Based on the above experiments, the optimized reaction conditions
were: 85 °Cfor 4 h in the presence of 1.0 mol% formic acid. This optimized reaction
condition was applied to the condensation reaction of β-diketones (acetylacetone and
benzoylacetone) with various anilines (Scheme 1), and the results are summarized in
Table 3.
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To show the efficacy of this method, variousanilines containing electron-withdrawing
groups (such as chloro, nitro and nitrile groups) and electron-donating groups (such as
aryl, methyl and methoxy groups) were treated with β-diketones to afford the
corresponding β-enaminones in good to excellent yields. This clearly demonstrates that
the electronic nature of substituents of the aromatic ring did not show any obvious effects
in terms of yields under these reaction conditions. Also, this method offers several
advantages such as better yields, shorter reaction times, cleaner reaction profiles, and
simple experimental and workup procedures. The additional advantage of this method is
the survival of various functional groups such as halo, nitrile, and nitro, thus allowing a
wide range of substitution patterns in the substrates. All reactions were clean and highly
efficient, and the products were obtained in good to excellent yields. All the products
were purified by general recrystallization method without column chromatography on
silica gel and characterized by 1H NMR, 13C NMR, mass spectrometry, infrared (IR)
spectroscopy, and elemental analysis. The compound (Z)-4-(4-
methoxyphenylamino)pent-3-en-2-one was also analyzed by single crystal X-ray
diffraction.
All 1H NMR spectra of the β-enaminones present a broad signal, which corresponds to
the protons of the amine group (N-H). The chemical shift of this proton appears between
11.93 -13.07 ppm, and is generally very sensitive to concentration, solvent, and
temperature. The protons of the methyl carried by the amino group appear between 1.15 -
2.13 ppm. The vinylic protons appear in the form of singlet between 4.98 -5.92 ppm. The
13C NMR spectra of β-enaminones present a signal characteristic of the sp2 carbon of the
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ketone function between 188.40 -199.45 ppm, whereas the sp3 carbon of the amine
function appears around 157.21 - 165.72 ppm. Vinylic carbons appear between 101.40
and 92.39 ppm. The IR spectra of all β-enaminones showν(C=O) stretching frequencies
around 1600-1650 cm-1, which correspond to the ketone. The wide broad ν(N-H)
stretching frequencies around 3420-3410 cm-1 are more significant and confirm well the
obtention of β-ketoamine and not of β-ketoimine.
Description Of The Crystal Structure
Crystals suitable for single crystal X-ray diffraction were grown from slow evaporation
from a methanol solution at room temperature. Crystallographic data for the compound
(Z)-4-(4-methoxyphenylamino)pent-3-en-2-one is shown in Table 4. Selected bond
lengths, bond angles and torsion angles are listed in Tables 5 and 6 respectively.
Complete bond lengths and bond angles, anisotropic thermal parameters, and calculated
hydrogen coordinates are deposited as supplementary materials. The structures were
solved by direct methods using the SHELXS-97 program.[20] A perspective view of (Z)-4-
(4-methoxyphenylamino)pent-3-en-2-one showing the atomic numbering scheme, is
depicted in Figure 1. Compound (Z)-4-(4-methoxyphenylamino)pent-3-en-2-one has been
shown by 1H NMR spectroscopy to exist in solution in the enaminone and not the enol-
imine form. IR spectroscopy shows only the enaminone form in the solid state and this
has been further confirmed by its crystal structure. Compound (Z)-4-(4-
methoxyphenylamino)pent-3-en-2-onecrystallized in the monoclinic space group P21/c,
with four molecules in the unit cell. In this compound,there is an absence of any lattice
held water molecules or organic solvent molecules in the unit cell of the determined
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structure. The O1=C2 and C3-C2 bond distances [1.2467(13) and 1.4200(15) Å,
respectively] further confirm the existence of the enamino-ketone. The bond distances in
the C3=C4-N1 chain indicate greater electron delocalization [C3=C4=1.3781(15) Å and
N1-C4=1.3509(13) Å]. The C-C bond distances in aromatic rings are in the normal range
of 1.37-1.50 Å, which is characteristic of delocalized aromatic rings. The C-C-C bond
angles in aromatic rings are around 120° with the variation being less than 2°, which is
characteristic of sp2-hybridized carbons. The title compound lies in two planes with plane
I [O1, C2, C3, C4 and N1] making a dihedral angle of 35.76 with plane II [C6, C7, C8,
C9, C11 and C12]. The methoxy group is slightly twisted away from the aniline ring,
with a C8-C9-O2-C10 torsion angle of 4.3(2)°. The molecular packing diagram (Figure
2) shows four layers of molecules, which are independently arranged in the unit cell.
Molecules forming each layer are connected through intermolecular hydrogen bonding.
In each layer, the molecules are alternatively parallel. The molecular packing diagram
also shows the presence of one intra-molecular hydrogen bond. One of the hydrogens, H1
of the NH group, is involved in intra-molecular hydrogen bonding with the O1 of the
C=O entity. This hydrogen bonding stabilizes the crystal packing.
CONCLUSION
In conclusion, we have presented an efficient and environmentally benign protocol for
the synthesis of β-enaminones from the reaction of β-diketones with various anilines in
the presence of 1.0 mol% formic acid. The simple work-up, mild reaction conditions, and
high yields make our methodology a valid contribution to the existing processes for β-
enaminone syntheses.
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EXPERIMENTAL
General Procedure For The Synthesis Of Β-Enaminones From The Condensation
Reaction Of Β-Diketones With Primary Amines
A mixture of β-diketone (10 mmol), aniline (10 mmol), and formic acid (1.0 mol%) were
heated at 85 °Cin 40 mL methanol for 4 hours. On cooling, the precipitated product was
filtered and recrystallized from a mixture of methanol and ether to afford β-enaminones.
All compounds are stable in air and light over a period of several months. The synthetic
pathway described in this work is outlined in Scheme 1.
Characterization Dataof Β-Enaminones
(Z)-4-(Phenylamino)Pent-3-En-One (3a)
211H NMR (300MHz, CDCl3) δ (ppm): 1.97 (s, 3H, CH3), 2.09 (s, 3H, CH3), 5.18 (s, 1H,
CH), 7.10-7.07 (m, 2H, ArH), 7.19-7.15 (m, 1H, ArH), 7.34-7.28 (m, 2H, ArH), 12.49 (s,
1H, NH). 13C NMR (100 MHz, CDCl3) δ19.61 (CH3), 28.96 (CH3), 97.41 (CH), 124.46,
125.31, 128.87, 138.50 (ArC), 159.98 (C-N), 195.86 (C=O).
(Z)-4-(P-Tolylamino)Pent-3-En-One (3b)
221H NMR (300MHz, CDCl3) δ (ppm): 1.91 (s, 3H, CH3), 2.05 (s, 3H, CH3), 2.29 (s, 3H,
CH3), 5.13 (s, 1H, CH), 6.95 (d, J=10.0Hz, 2H, Ph), 7.09 (d, J=10.0 Hz, 2H, Ph), 12.38
(s, 1H, NH). 13C NMR (100 MHz, CDCl3) δ19.52 (CH3), 20.67 (CH3), 28.84 (CH3),
97.00 (CH), 124.57, 129.44, 135.24, 135.78 (ArC), 160.53 (C-N), 195.60 (C=O).
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(Z)-4-(4-Methoxyphenylamino)Pent-3-En-One (3c)
231H NMR (300MHz, CDCl3) δ (ppm): 1.77 (s, 3H, CH3); 1.96 (s, 3H, CH3); 3.65 (s, 3H,
OCH3); 5.03 (s, 1H, CH); 6.75-6.72 (m, 2H, ArH); 6.91-6.88 (m, 2H, ArH); 12.21 (s, 1H,
NH). 13C NMR (100 MHz, CDCl3) δ19.13 (CH3), 28.55 (CH3), 54.90 (OCH3), 96.42
(CH), 113.80, 126.08, 130.96, 157.27 (ArC), 160.82 (C-N), 195.17 (C=O).
(Z)-4-(4-Chlorophenylamino)Pent-3-En-One (3d)
221H NMR (300MHz, CDCl3) δ (ppm): 1.97 (s, 3H, CH3), 2.09 (s, 3H, CH3), 5.20 (s, 1H,
CH), 7.03 (d, J = 8.4 Hz, 2H, ArH), 7.29 (d, J = 8.4 Hz, 2H, ArH), 12.44 (s, 1H, NH). 13C
NMR (100 MHz, CDCl3) δ19.59 (CH3), 29.02 (CH3), 97.95 (CH), 125.61, 129.01,
130.75, 137.16 (ArC), 159.53 (C-N), 196.29 (C=O).
(Z)-4-(4-Nitrophenylamino)Pent-3-En-One (3e)
241H NMR (300MHz, CDCl3) δ (ppm):2.13 (s, 3H, CH3), 2.18 (s, 3H, CH3), 5.32 (s, 1H,
CH), 7.16 (d, J=9 Hz, 2H, ArH), 8.18 (d, J=9 Hz, 2H, ArH), 12.76 (s, 1H, NH). 13C NMR
(100 MHz, CDCl3) δ20.81 (CH3), 29.86 (CH3), 101.40 (CH), 122.14, 125.40, 143.77,
145.53 (ArC), 157.21 (C-N), 198.11 (C=O).
(Z)-4-(4-Oxopent-2-En-2-Ylamino)Benzonitrile (3f)
241H NMR (300MHz, CDCl3) δ (ppm): 2.11 (s, 3H, CH3), 2.12 (s, 3H, CH3), 5.28 (s, 1H,
CH), 7.14 (d, J=8 Hz, 2H, ArH), 7.59 (d, J=8 Hz, 2H, ArH), 12.67 (s, 1H, NH). 13C NMR
(100 MHz, CDCl3) δ20.36 (CH3), 29.50 (CH3), 100.41 (CH), 107.27, 118.66, 122.83,
133.25 (ArC), 143.26 (C-N), 157.47 (C-N), 197.55 (C=O).
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(Z)-4-(2,6-Dimethylphenylamino)Pent-3-En-One (3g)
251H NMR (300MHz, CDCl3) δ (ppm): 1.60 (s, 3H, CH3), 2.08 (s, 3H, CH3), 2.17 (s, 6H,
(CH3)2), 5.19(s, 1H, CH), 7.11-7.04 (m, 3H, ArH), 11.91(1H, s, NH). 13C NMR (100
MHz, CDCl3) δ18.08 (CH3), 18.72 (CH3), 28.85 (CH3), 95.64 (CH), 127.29, 128.05,
135.93, 136.33 (ArC), 162.80 (C-N), 195.85 (C=O).
(Z)-4-(2,6-Diisopropylphenylamino)Pent-3-En-One (3h)
251H NMR (300MHz, CDCl3) δ (ppm): 1.14 (d, J = 6.6 Hz, 1H, CH(CH3))2, 1.21 (d, J =
7.2 Hz, 1H, CH(CH3))2, 1.63 (1H, s, CH3CNHAr), 2.12 (1H, s, CH3COC), 3.02 (sept, J =
6.8 Hz, 1H, CHMe2), 5.21 (s, 1H, CH), 7.18-7.15 (2H, m, ArH), 7.32-7.27 (1H, m, ArH),
12.04 (1H, s, NH). 13C NMR (100 MHz, CDCl3) δ19.14 (CH3CNHAr), 22.63, 24.54
(CH(CH3)2), 28.43 (CHMe2), 28.98 (CH3C=O), 95.55 (CH), 123.52, 128.23, 133.42,
146.22(ArC), 163.39(HC(CNHAr), 195.81 (C=O).
(Z)-1-Phenyl-3-(Phenylamino)But-2-En-1-One (3i)
261H NMR (300MHz, CDCl3) δ (ppm): 2.13 (s, 3H, CH3), 5.89 (s, 1H, CH), 7.22-7.16 (m,
3H,ArH), 7.37-7.34 (m, 2H,ArH), 7.45-7.40 (m, 3H,ArH); 7.93-7.91 (m, 2H,ArH); 13.11
(s, 1H, NH). 13C NMR (100 MHz, CDCl3) δ20.39 (CH3), 94.18 (CH), 124.69, 125.70,
126.99, 128.22, 129.10, 130.84, 138.56, 139.93 (ArC), 162.16 (C-N), 188.59 (C=O).
(Z)-1-Phenyl-3-(P-Tolylamino)But-2-En-1-One (3j)
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271H NMR (300MHz, CDCl3) δ (ppm): 2.11 (s, 3H, CH3), 2.35 (s, 3H, CH3), 5.87 (s, 1H,
CH), 7.09-7.05 (m, 2H,ArH), 7.18-7.14 (m, 2H,ArH), 7.46-7.40 (m, 3H,ArH), 7.93-7.89
(m, 2H,ArH), 13.02 (s, 1H, NH).13C NMR (100 MHz, CDCl3) δ20.34 (CH3), 20.91
(CH3), 93.87 (CH), 124.80, 126.99, 128.23, 129.71, 130.77, 135.70, 135.90, 140.03
(ArC), 162.65 (C-N), 188.43 (C=O).
(Z)-3-(4-Methoxyphenylamino)-1-Phenylbut-2-En-1-One (3k)
281H NMR (300MHz, CDCl3) δ (ppm): 2.06(s, 3H, CH3), 3.80 (s, 3H, OCH3), 5.86 (s,
1H, CH), 6.90-6.87 (m, 2H,ArH), 7.11-7.08 (m, 2H,ArH), 7.45-7.40 (m, 3H,ArH), 7.93-
7.91 (m, 2H,ArH), 12.94 (s, 1H, NH). 13C NMR (100 MHz, CDCl3) δ20.17 (CH3), 55.38
(OCH3), 93.45 (CH), 114.24, 126.50, 126.93, 128.17, 130.69, 131.33, 140.04, 157.74
(ArC), 163.06 (C-NH), 188.28 (C=O).
(Z)-3-(4-Chlorophenylamino)-1-Phenylbut-2-En-1-One (3l)
291H NMR (300MHz, CDCl3) δ (ppm): 2.13 (s, 3H, CH3), 5.91 (s, 1H, CH), 7.12-7.08 (m,
2H, ArH), 7.35-7.32 (m, 2H, ArH), 7.46-7.43 (m, 3H, ArH), 7.92-7.89 (m, 2H, ArH),
13.07 (s, 1H, NH). 13C NMR (100 MHz, CDCl3) δ20.38 (CH3), 94.65 (CH), 125.89,
127.06, 128.30, 129.29, 131.06, 137.25, 139.74 (ArC), 161.69 (C-NH), 188.95 (C=O).
(Z)-3-(2,6-Dimethylphenylamino)-1-Phenylbut-2-En-1-One (3m)
291H NMR (300MHz, CDCl3) δ (ppm): 1.74(s, 3H, CH3), 2.22 (s, 6H, 2CH3), 5.96 (s, 1H,
CH), 7.13-7.07 (m, 3H,ArH), 7.43-7.41 (m, 3H,ArH), 8.00-7.99 (m, 2H,ArH), 12.64 (s,
1H, NH). 13C NMR (100 MHz, CDCl3) δ17.79 (2,6-(CH3)2-C6H3), 18.90 (CH3), 91.87
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(CH), 126.63, 127.07, 127.76, 127.82, 130.29, 135.33, 136.00, 139.57 (ArC), 164.21
(CN), 187.93 (C=O).
Supplementary Material
Crystallographic data for the structure reported in this article have been deposited with
the Cambridge Crystallographic Data Center with the deposition number 831504. A copy
of the data can be obtained free of charge from the Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [fax: +44 1223 336-033; e-mail: deposit@ccdc.cam.ac.uk or
www.ccdc.cam.ac.uk].
ACKNOWLEDGMENT
The authors thank the National Science Foundation (CHE-0911061) for financial support.
We also acknowledge the Ministerio de Ciencia y Tecnología de Costa Rica (MICIT),
ConsejoNacionalparaInvestigacionesCientíficas y Tecnológicas (CONICIT), and the
Centro de Electroquímica y EnergíaQuímica (CELEQ) at the Universidad de Costa Rica
for providing partial financial support for an internship for Diego Gonzalez-Flores at
Central Michigan University.
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Table 1 Condensation reaction of acetylacetone with aniline in the presence of different
liquid acid catalystsa
Entry Solvent Catalyst
Time (h) Temperature/°C Yieldsb (%)
1
2
3
4
5
CH3OH H2SO4
CH3OH HCl
4
4
85
85
85
85
85
58
54
61
98
53
CH3OH CH3C6H4SO3H 4
CH3OH HCOOH
4
CH3OH CH3COOH
4
aReaction conditions: acetylacetone (1.03 g, 10 mmol), aniline (0.91 g, 10 mmol), acid
catalyst (1.0 mol%). bIsolated yields.
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Table 2. Condensation reaction of acetylacetone with aniline in the presence of different
organic solventsa
Entry Solvent
Catalyst
HCOOH
HCOOH
HCOOH
Time (h) Temperature/°C Yieldsb (%)
1
2
3
4
5
6
CHCl3
CHCl2
CH3OH
4
4
4
4
4
4
85
85
85
85
85
85
54
55
98
87
70
76
CH3CH2OH HCOOH
C6H5CH3
C6H6
HCOOH
HCOOH
aReaction conditions: acetylacetone (1.03 g, 10 mmol), aniline (0.91 g, 10 mmol), formic
acid catalyst (1.0 mol%). bIsolated yields.
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Table 3. Reaction of β-diketones with anilinescatalysed by formic acid in methanola
Entry Diketone
Primary Amine
NH2
Product
Mp (°C) Time Yieldb(
(h)
4
%)
98
O
O
1
47-48
H3C
C
O
HN
H3C
CH
3a
O
O
O
O
O
O
NH2
2
3
4
67-68
41-42
60-62
4
4
4
96
97
98
H3C
H3C
H3C
C
C
C
O
HN
H3C
CH3
3b
CH3
NH2
O
HN
H3C
CH3
3c
OCH3
NH2
O
HN
H3C
CH3
Cl
3d
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O
O
NH2
5
142-143 4
95
H3C
C
O
HN
H3C
CH3
3e
NO2
NH2
O
O
O
O
6
7
86-88
48-49
4
4
94
95
H3C
C
O
HN
H3C
CH3
3f
CN
NH2
H3C
H3C
C
CH
H3C
O
HN
H3C
CH
3g
H3C
O
O
CH3
NH2
8
45-47
4
93
H3C
C
H3C
H3C
O
HN
H3C
CH
H
3h
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O
NH2
9
108-110 4
97
O
HN
C
3i
O
NH2
10
88-89
4
4
96
O
HN
CH3
CH3
NH2
3j
O
O
11
12
92-93
96
94
O
HN
CH3
OCH3
NH2
3k
128-129 4
O
HN
CH
Cl
3l
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H3C
HN
O
NH2
13
109-110 4
95
H3C
CH
O
3m
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Table 4 Crystal data and the structure refinement of (Z)-4-(4-methoxyphenylamino)pent-
3-en-2-one
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C12H15NO2
205.25
296 (2) K
0.71073 Å
Monoclinic
P21/c
11.2440(4)
8.5311(3)
11.6168(4)
90°
102.163(2)°
90°
b (Å)
c (Å)
α (o)
β (o)
γ (o)
Volume (Å3)
Z
1089.31(7)Å
4
3
Density (calculated) (Mg/m3)
3
1.252 Mg/m
Absorption coefficient (mm-1)
-1
0.085 mm
440
F000
Crystal size
3
0.45 x 0.18 x 0.14 mm
Theta range for data collection
1.85 to 30.93°
Index ranges
-16 ≤ h ≤ 16, -12 ≤ k ≤ 12, -16 ≤ l ≤ 16
18529
Reflections collected
Independent reflections
Refinement method
3448 [R(int) = 0.0218]
2
Full-matrix least-squares on F
Completeness to theta = 25.50°
Max. and min. Transmission
Data / restraints / parameters
99.6 %
0.7461 and 0.6940
3448 /0 /143
2
1.032
Goodness-of-fit on F
Final R indices [I>2sigma(I) = 2608 data] R1 = 0.0437, wR2 = 0.1198
R indices (all data)
R1 = 0.0594, wR2 = 0.1329
0.159 and -0.184 e.Å
Largest diff. peak and hole (e.Å-3)
-3
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Table 5. Selected bond lengths(Å) and bond angles(o) of (Z)-4-(4-
methoxyphenylamino)pent-3-en-2-one
Bond length
N(1)-C(4)
(Å)
1.3509(13)
1.4203(13)
1.2467(13)
1.3862(15)
1.3896(16)
1.3923(15)
1.3774(15)
1.3736(14)
1.3823(16)
1.3900(16)
1.4139(18)
1.3781(15)
1.4200(15)
1.4968(15)
1.5090(16)
(°)
N(1)-C(6)
O(1)-C(2)
C(7)-C(6)
C(7)-C(8)
C(6)-C(12)
C(12)-C(11)
C(9)-O(2)
C(9)-C(8)
C(9)-C(11)
O(2)-C(10)
C(3)-C(4)
C(3)-C(2)
C(4)-C(5)
C(2)-C(1)
Bond angle
C(4)-N(1)-C(6)
C(6)-C(7)-C(8)
C(7)-C(6)-C(12)
C(7)-C(6)-N(1)
C(12)-C(6)-N(1)
C(11)-C(12)-C(6)
O(2)-C(9)-C(8)
O(2)-C(9)-C(11)
C(8)-C(9)-C(11)
C(9)-O(2)-C(10)
C(4)-C(3)-C(2)
N(1)-C(4)-C(3)
N(1)-C(4)-C(5)
C(3)-C(4)-C(5)
O(1)-C(2)-C(3)
O(1)-C(2)-C(1)
C(3)-C(2)-C(1)
C(9)-C(8)-C(7)
C(12)-C(11)-C(9)
128.05(9)
120.79(10)
118.36(10)
124.26(9)
117.36(9)
120.89(10)
124.93(11)
116.03(10)
119.04(10)
117.52(11)
125.19(9)
121.11(10)
119.89(10)
118.98(10)
123.38(10)
118.95(10)
117.64(10)
120.32(10)
120.48(10)
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Table 6. Torsion angles [°] for (Z)-4-(4-methoxyphenylamino)pent-3-en-2-one
C(4)-N(1)-C(6)-C(7)
C(4)-N(1)-C(6)-C(12)
C(6)-N(1)-C(4)-C(3)
C(6)-N(1)-C(4)-C(5)
C(8)-C(7)-C(6)-N(1)
C(8)-C(7)-C(6)-C(12)
C(6)-C(7)-C(8)-C(9)
-44.9(2)
136.7(1)
-167.4(1)
10.9(2)
177.7(1)
-3.8(2)
1.7(2)
N(1)-C(6)-C(12)-C(11) -178.6(1)
C(7)-C(6)-C(12)-C(11) 2.8(2)
C(6)-C(12)-C(11)-C(9) 0.3(2)
C(8)-C(9)-O(2)-C(10)
4.3(2)
C(11)-C(9)-O(2)-C(10) -176.2(1)
O(2)-C(9)-C(8)-C(7)
C(11)-C(9)-C(8)-C(7)
-179.1(1)
1.5(2)
O(2)-C(9)-C(11)-C(12) 178.0(1)
C(8)-C(9)-C(11)-C(12) -2.5(2)
C(2)-C(3)-C(4)-N(1)
C(2)-C(3)-C(4)-C(5)
C(4)-C(3)-C(2)-O(1)
C(4)-C(3)-C(2)-C(1)
5.2(2
-173.0(1)
-5.4(2)
172.5(1)
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Scheme. 1. Synthesis of β-enaminonesby the condensation reaction of β-diketones with
anilinesin the presence of formic acid.
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Figure 1. Molecular structure of (Z)-4-(4-methoxyphenylamino)pent-3-en-2-oneshowing
50% probability displacement ellipsoids.
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Figure 2. Packing diagram of (Z)-4-(4-methoxyphenylamino)pent-3-en-2-
oneapproximately viewed along the b axis.
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