Synthesis and structure of novel 1-aryl-4,4,4-trichloro-1,3-butanediones

Article abstract of DOI:10.1080/00397911.2010.530376

Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass spectrometry, and ¹H/¹³C nuclear magnetic resonance (NMR) measurements. The ¹H/¹³C NMR data showed that trichloromethyl-β-diketones 2a-k in solution are predominantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl- 1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed that these compounds are cis-ketoenol tautomers. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communcations1 to view the free supplemental file. Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397911.2010.530376

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Synthesis and Structure of Novel 1-
Aryl-4,4,4-trichloro-1,3-butanediones
Alex F. C. Flores a , Mauro J. Martins a , Leandro M. Frigo a , Pablo
Machado a , Patrick T. Campos a & Juliana L. Malavolta a
a NUQUIMHE, Departamento de Química, Universidade Federal de
Santa Maria, Santa Maria, Brazil
Accepted author version posted online: 17 Aug 2011.Version of
record first published: 01 Nov 2011.
To cite this article: Alex F. C. Flores , Mauro J. Martins , Leandro M. Frigo , Pablo Machado , Patrick
T. Campos & Juliana L. Malavolta (2012): Synthesis and Structure of Novel 1-Aryl-4,4,4-trichloro-1,3-
butanediones, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 42:5, 727-737
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Synthetic Communications1, 42: 727–737, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.530376
SYNTHESIS AND STRUCTURE OF NOVEL
1-ARYL-4,4,4-TRICHLORO-1,3-BUTANEDIONES
Alex F. C. Flores, Mauro J. Martins, Leandro M. Frigo,
Pablo Machado, Patrick T. Campos, and Juliana L. Malavolta
´
NUQUIMHE, Departamento de Quımica, Universidade Federal de Santa
Maria, Santa Maria, Brazil
GRAPHICAL ABSTRACT
Abstract Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80–97%) were
synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by
acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass
spectrometry, and 1H/13C nuclear magnetic resonance (NMR) measurements. The
1H/13C NMR data showed that trichloromethyl-b-diketones 2a–k in solution are predomi-
nantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl-
1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias
toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed
that these compounds are cis-ketoenol tautomers.
Supplemental materials are available for this article. Go to the publisher’s online edition
of Synthetic Communcations1 to view the free supplemental file.
Keywords Acetal acylation; b-diketones; keto–enol equilibrium; trichloromethyl-b-
diketones
INTRODUCTION
1,3-Diketones have interesting properties and have been widely studied both
experimentally and theoretically because they are important organic reagents.[1–3]
Received June 1, 2010.
Address correspondence to Alex F. C. Flores, Departmento de Quımica, Universidade Federal de
´
Santa Maria 97105 900, Santa Maria, RS, Brazil. E-mail: alexflores@smail.ufsm.br
727

728
A. F. C. FLORES ET AL.
They are extensively used as versatile heterocyclic precursors[4–6] and chelating
reagents for metal ions.[7–9] Many studies have reported the synthesis of 1,3-
diketones.[10–12] The most common method employs the Claisen condensation of
ketone enolates and an ester.[2,13–16] However, only a limited number of procedures
for this method has been reported: 1,3-diketones synthesized from metal enolate acy-
lation show poor chemoselectivity because their a-hydrogens are more acidic than
those of the starting ketones.[17] In addition, the alkaline medium in metal enolate
acylation limits the scope to unreactive alkali sidechains for the resultant 1,3-
diketones. Because of the importance of this class of compound, we have applied
the acetal acylation method to C-C bond formation in a b-alkoxyvinyl trihalomethyl
ketone building block and have been studying hydrolysis to the respective b-dicarbo-
nyl derivatives.[18,19] As a result, we have developed a convenient procedure for the
synthesis of novel trichloromethyl-b-diketones. Although we previously demon-
strated the synthesis of trichloroacetyl-cycloalkanones and 4,4,4-trichloro-1-
heteroaryl-1,3-butanediones, a review of the literature on the trichloromethyl-b-
diketones revealed that they are still uncommon. At the same time, 1-aryl-4,4,
4-trifluoro-1,3-butanediones have been widely used for the synthesis of coordination
complexes[20–22] and trifluoromethylated heterocyclic compounds.[23,24]
Based on our previous experience, we continued our search for new trichloro-
methyl containing b-diketones that can be used in coordination chemistry and
organic synthesis. Herein, we report the synthesis and structure of novel 1-aryl-
4,4,4-trichloro-1,3-butanediones, as well as their direction of enolization.
RESULTS AND DISCUSSION
The 1-aryl-1,1-dimethoxyethanes 1a–k and 1,1-dimethoxy-1-phenyl-propane 1l
were prepared using a previously reported procedure.[18] Acetals 1a–l reacted with
trichloroacetyl chloride in pyridine without solvent. Acetal acylation and subsequent
hydrolysis of the b-alkoxyvinyl trichloromethyl ketone were carried out in one reac-
tion (Scheme 1). Hydrolysis was performed in 1mol Lꢀ1 sulfuric acid solution for 2h
at room temperature. The diketones 2a–l were obtained as crystalline solids, whose
colors varied from white to yellow depending on the aryl substituent (see the experi-
mental section).
The 1H=13C nuclear magnetic resonance (NMR) spectra of all products
showed signals attributed to trichloromethyl-b-diketones. b-Diketones have two
forms, the keto–enol and diketo forms. The NMR analyses of 1-aryl-4,4,4-
trichloro-1,3-butanediones (2) revealed that, except for 2l, they were all in enolic
1
form. An important feature of the H NMR spectra of compounds 2a–k was the
presence of a broad singlet in the region of 14.0 ppm, resulting from the enolic hydro-
gen. Another feature was the presence of a singlet in the region of 6.7–6.8 ppm from
vinylic hydrogen predominantly in the keto–enol form. However, for compound 2l,
the 1H NMR spectrum showed only signals of diketone form as a quartet at 4.0 ppm
from the coupling of the H2 with the a-methyl substituent (JHH ¼ 7 Hz) and the
respective methyl as a doublet at 1.63 ppm. Thus, 2l was assigned as entirely diketo
in form.
The 13C(H) NMR spectra for compounds 2a–k showed a signal at 89–95 ppm,
typical of vinylic C-sp2 in the keto–enol form. For compound 2l, a signal in the range

TRICHLOROACETYLACETOPHENONES
729
Scheme 1. Synthesis of 1-aryl-4,4,4-trichloro-1,3-butanediones.
of 47 ppm for C-a confirmed the diketo structure (e.g., compare Figs. S5 and S32,
available online in the supplementary information). The 13C NMR data for carbonyl
carbons showed chemical shifts for carbonyls near the trichloromethyl group (C2)
for products 2a–l, at around 185–187 ppm. However, the chemical shifts from car-
bonyl carbons near the aromatic substituent were considerably different between
cis-keto–enols 2a–k at around 176–181ppm and diketo 2l, which showed a chemical
shift at 194 ppm. Based on these data, the cis-keto–enols 2a–k were assigned the
structure 4-aryl-1,1,1-trichloro-4-hydroxy-3-buten-2-one, because no signals were
observed for diketo 1-aryl-4,4,4-trichlorobutan-1,3-dione or cis-ketoenol 1-aryl-4,
4,4-trichloro-3-hydroxy-2-buten-1-one (Scheme 2).
Scheme 2. Tautomeric equilibrium for b-diketones 2a–l.

730
A. F. C. FLORES ET AL.
Compounds 2g and 2i were subjected to single-crystal x-ray analysis (Tables 1,
2, and 3), which confirmed the solid-state molecular structure cis-keto–enol proposed
for compounds 2a–k with a Z-configuration on the alkene moiety and the intramol-
ecular hydrogen bond O3—H1ꢀN1 (Fig. 1). In the solid state, the enolenone
fragments [O(21) ¼ C(2)–C(3) ¼ C(4)–O(41)] were nearly planar, with root mean
˚
square (rms) deviations from the plane of 0.0056 and 0.0024 A for compounds 2g
and 2i, respectively. The C(2) atom deviated most, by ꢀ0.0069 (17) and ꢀ0.0035
˚
(12) A for 2g and 2i, respectively. Planarity was confirmed by the torsion angles
ꢁ
ꢁ
=
=
O(21) C(2)–C(3) C(4), which were ꢀ0.8(4) and ꢀ0.9(3) in 2g and 2i, respectively,
and the torsion angles C(2)–C(3) ¼ C(4)–O(41), which were ꢀ0.6(4)ꢁ and ꢀ0.7(3)ꢁ in
Table 1. General and crystal data and summary of intensity data collection and structure refinement for
compounds 2g and 2i
Compound
2g
2i
Formula
Mr
C10H6BrCl3O2
344.41
733496
C10H6Cl3NO4
310.51
733495
CCDCa
Temperature (K)
302(2)
0.71073
296(2)
˚
Wavelength (A)
0.71073
Monoclinic
P21=c
Crystal system
Space Group
Monoclinic
P2(1)=n
Unit cell parameters
˚
a (A)
˚
13.5020 (11)
6.7499 (5)
6.7037 (14)
16.899 (4)
11.470 (3)
b (A)
˚
c (A)
13.7410 (11)
90
91.149 (5)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
102.403 (8)
90
90
1269.0 (5)
3
˚
V (A )
1252.06 (17)
4
1.827
Z
4
1.625
Density (calculated) (g cmꢀ3
)
Absorption coefficient (mmꢀ1
F (000)
Crystal size (mm)
h range for data collection (ꢁ)
h,k,l range
)
3.903
672
0.726
624
0.58 ꢂ 0.55 ꢂ 0.41
2.97 to 31.58
ꢀ19 ꢃ h ꢃ 19
ꢀ9 ꢃ k ꢃ 9
0.75 ꢂ 0.25 ꢂ 0.18
2.18 to 31.03
ꢀ9 ꢃ h ꢃ 9
ꢀ24 ꢃ k ꢃ 24
ꢀ16 ꢃ l ꢃ 16
0.89358=0.74739
15927
ꢀ20 ꢃ l ꢃ 15
1.0000=0.5080
17965
Tmax=Tmin
Reflections collected
Independent reflections
Data=restraints=parameters
Absorption correction
Refinement method
4080 [R(int) ¼ 0.0841]
4080=0=145
Gaussian
4041 [R(int) ¼ 0.0343]
4041=0=163
Gaussian
Full-matrix least-squares on F2
R1 ¼ 0.0402, wR2 ¼ 0.1054
R1 ¼ 0.0934, wR2 ¼ 0.1147
0.855
Full-matrix least-squares on F2
R1 ¼ 0.0452, wR2 ¼ 0.1083
R1 ¼ 0.0828, wR2 ¼ 0.1319
1.048
Final R indices [I > 2r(I)]
R indices (all data)
Goodness of fit on F2
Largest diff. peak and hole (eA
ꢀ3
˚
)
0.756 and ꢀ0.697
0.441 and ꢀ0.467
aCCDC 733495 (2i) and 733496 (2g) contain the supplementary crystallographic data for this paper.
These data are available free of charge via www.ccdc.cam.ac.uk/data_request/cif, by e-mailing data_
request@ccdc.cam.ac.uk, or by contacting CCDC.

TRICHLOROACETYLACETOPHENONES
731
Table 2. Select geometric parameters (A, ꢁ) obtained experimentally for 2g and 2i
˚
2g
2i
˚
Bond lengths (A)
C(1)–C(2)
C(2)–C(3)
1.558(4)
1.416(3)
1.358(4)
1.222(3)
1.328(3)
1.756(3)
1.477(3)
1.902(3)
—
1.548(3)
1.433(3)
1.359(3)
1.224(2)
1.326(2)
1.766(2)
1.482(3)
—
C(3)–C(4)
C(2)-O(21)
C(4)-O(41)
C(1)-Cl(1)
C(4)–C(41)
C(44)–Br
C(44)–N(44)
N(44)–O(45)
1.486(3)
1.212(3)
1.215(3)
—
—
N(44)–O(46)
Bond angles (ꢁ)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
O(21)–C(2)–C(3)
C(3)–C(4)–O(41)
C(3)–C(4)–C(41)
O(21)–C(2)–C(1)
O(41)–C(4)–C(41)
C(43)–C(44)–Br
C(43)–C(44)–N(44)
C(44)-N(44)–O(45)
O(45)–N(44)–O(46)
117.9(2)
120.9(2)
125.2(2)
122.9(2)
124.5(2)
116.9(2)
112.6(2)
119.4(2)
–
118.19(17)
120.20(19)
124.01(19)
122.80(18)
124.79(19)
117.80(17)
112.41(18)
—
118.7(2)
118.4(3)
124.0(2)
—
—
=
=
=
2g and 2i, respectively. For C(1) C(2) C(3) C(4), the enolenone had a torsion
angle of 179.9(2)ꢁ in 2g and 179.41(19)ꢁ in 2i, indicating that the C(1) atom (a mem-
ber of the trichlormethyl group) was almost in the same plane as the enaminone frag-
ment. The geometry of the enolenone system was similar to that reported in the
literature.[25] The least-squares plane angles between the enolenone and the phenyl
group were 11.15(14)ꢁ and 4.23(12)ꢁ for 2g and 2i, respectively. The interatomic dis-
tances between the proton acceptor and proton donor oxygen atoms, O(41) ꢄ ꢄ ꢄ O(21),
´
˚
were 2.611(3) and 2.576(2) A in molecules 2g and 2i, respectively, confirming the
presence of the intramolecular hydrogen bond.[26]
CONCLUSION
In conclusion, our methodology can be used to prepare various 1-aryl-4,4,4-
trichloro-1,3-butanediones. To the best of our knowledge, this series of compounds
ꢁ
˚
Table 3. Hydrogen bonding geometry in 2g and 2i (A,
)
Compound
D-HꢄꢄꢄA
D-H
HꢄꢄꢄA
DꢄꢄꢄA
D-HꢄꢄꢄA
Symmetry codes
2g
O(41)–H(41)ꢄꢄꢄO(21)
O(41)–H(41)ꢄꢄꢄO(21)
O(41)–H(41)ꢄꢄꢄO(21)
O(41)–H(41)ꢄꢄꢄO(21)
0.82
0.82
0.82
0.82
1.90
2.35
1.86
2.36
2.611(3)
2.981(3)
2.576(2)
2.999(2)
145.0
134.7
145.8
135.7
ꢀx þ 1, ꢀy, ꢀz þ 1
2i
ꢀx þ 3, ꢀy þ 1, ꢀz þ 2

732
A. F. C. FLORES ET AL.
Figure 1. Molecular structure of compounds 2g and 2i, with ellipsoids for nonhydrogen atoms, drawn at
the 50% probability level. H atoms are drawn as arbitrary spheres. (Figure is provided in color online.)
has never been reported, with the exception of compounds 2a and 2l.[19] Ten novel
trichloromethyl-1,3-diketones were synthesized in good yields. The b-trichloro-
methyl-b-diketones 2a–k were in cis-keto–enol form in solution, as revealed by
NMR spectroscopy. In contrast, the novel trichloromethyl-b-diketone 2l was found
only in the diketo form in solution. Based on the NMR and x-ray data, the different
aryl substituents did not affect keto–enol equilibrium in the 1-aryl-4,4,4-trichloro-
1,3-butanediones. The x-ray data revealed that trichloromethyl-b-diketones are cis-
keto–enols in the solid state too.
EXPERIMENTAL
The synthesis of 1-aryl-1,1-dimethoxyacetals has been reported elsewhere.[20]
Trichloroacetyl chloride and pyridine were used as obtained from commercial
suppliers; chloroform was purified before use. A 1mol Lꢀ1 solution of H2SO4 was
prepared by dissolving 98% H2SO4 in 100 mL distilled water. The yields of the iso-
lated compounds were measured. Melting points were determined using a Reichert
1
Thermovar apparatus and were uncorrected. The H and 13C spectra were recorded
at 298 K on a Bruker DPX 400 spectrometer (1H at 400.13 MHz, 13C at 100.63 MHz)
with a digital resolution of ꢅ0.01 ppm. All chemical shifts were expressed in parts per

TRICHLOROACETYLACETOPHENONES
733
1
million (ppm), and H and 13C were reported with respect to internal tetramethylsi-
lane (TMS). Solutions of 0.1mol Lꢀ1 CDCl3 were used. H-H and C-F coupling con-
stants were measured in hertz (Hz). Mass spectra were registered using an HP 5973
mass selective detector connected to an HP 6890 GC and interfaced with a Pentium
PC. The GC was equipped with a split–splitless injector, auto-sampler, and
cross-linked HP-5 capillary column (30 m, 0.32mm internal diameter), and helium
was used as the carrier. Elemental analyses were performed on a Perkin-Elmer
2400 CHN elemental analyzer (Sa˜o Paulo University, Sa˜o Paulo, Brazil). Diffraction
measurements were made using graphite-monochromatized Mo Ka radiation with
[27]
˚
k ¼ 0.71073 A on a Bruker SMART CCD diffractometer.
The structures were
solved by direct methods using the SHELXS-97 program,[28] and refined on F2 using
a full-matrix least-squares package by SHELXL97.[29] Absorption correction was
performed using Gaussian methods.[30] Anisotropic displacement parameters for
nonhydrogen atoms were applied. The hydrogen atoms were placed at calculated
positions of 0.96 A (methyl CH3), 0.97 A (methylene CH2), 0.98 A (methine CH),
˚
and 0.93 A (aromatic CH) using a riding model. Hydrogen isotropic thermal para-
˚
˚
˚
meters were kept equal to Uiso(H) ¼xUeq (carrier C atom), with x ¼ 1.5 for methyl
groups and x ¼ 1.2 otherwise. The valence angles C-C-H and H-C-H of the methyl
groups were set to 109.5 ꢁ, and H atoms were allowed to rotate around the C-C
bond. Molecular graphics were prepared using ORTEP3 for Windows.[31]
General Procedure for the Synthesis of
1-Aryl-4,4,4-trichlorobutan-1,3-dione
A solution of trichloroacetyl chloride (7.0 mL, 60 mmol) in chloroform (20 mL)
was added dropwise to a stirred solution of 1-aryl-1,1-dimethoxyethanes 1a–k, pyri-
dine (5.2 mL, 60 mmol), and 1,1-dimethoxy-1-phenylpropane 1l (30 mmol) in chloro-
form (50 mL) kept at 0 ꢁC. The mixture was stirred for 8 h at 0–25 ꢁC, quenched with
a 2 mol Lꢀ1 sulfuric acid solution (30 mL), and then stirred for 2h at 40 ꢁC. The
organic layer was dried with sodium sulfate, the solvent was evaporated, and pro-
ducts were obtained with good purity. The crystalline compounds were purified by
recrystallization from hexane.
Data
1,1,1-Trichloro-1-hydroxy-4-phenyl-1-buten-2-one (2a). Yield 85%, oil;
IR (film) nmax=cmꢀ1: 3400 (OH), 3089 (C CH), 2926, 2878 (C C), 1592, 1568
=
1
=
=
=
(O C-C C), 1493, 1455 (C-O), 1255, 1081; H NMR (400 MHz, CDCl3): d 6.8 (s,
1H, H3), 7.5 (m, 2H, Ph), 7.6 (m, 1H, Ph), 7.9 (m, 2H, Ph), 14.3 (s, br, 1H, OH);
13C NMR (100 MHz, CDCl3): d 186.2 (C2), 180.8 (C4), 133.4, 132.5, 128.9, 127.2
(Ph), 95.0 (C1), 89.6 (C3); MS (70 eV) m=z 268 (Mþ þ 4, 4), 266 (Mþ þ 2, 12), 264
(Mþ, 12), 203 (16), 201 (25), 147 (100), 105 (100), 77 (100), 69 (100). Anal. calcd.
for C10H7Cl3O2: C, 45.24; H, 2.66. Found: C, 45.27; H, 2.68.
1,1,1-Trichloro-4-hydroxy-4-(4-toluil)-1-buten-2-one (2b). Yield 88%, mp:
55–57 ꢁC; IR (KBr) nmax=cmꢀ1: 3447 (OH), 3093 (C CH), 2930, 2885 (C C), 1611,
=
=
1
1585 (O C-C C), 1561, 1507 (C-O), 1434, 1238, 1121; H NMR (400 MHz, CDCl3):
=
=

734
A. F. C. FLORES ET AL.
d 2.4 (s, 3H, 4-CH3), 6.7 (s, 1H, H3), 7.3 (m, 2H, Ar), 7.8 (m, 2H, Ar), 14.4 (s, br, 1H,
OH); 13C NMR (100 MHz, CDCl3): d 185.9 (C2), 181.2 (C4), 144.5, 129.7, 129.6,
127.2 (Ar), 99.9 (C1), 89.0 (C3), 21.7 (4-CH3); MS (70 eV) m=z 282 (Mþ þ 2, 4),
280 (Mþ, 4), 217 (10), 215 (12), 161 (100), 119 (65), 91 (30), 69 (50). Anal. calcd.
for C11H9Cl3O2: C, 47.26; H, 3.25. Found: C, 47.5; H, 3.4.
1,1,1-Trichloro-4-hydroxy-4-(3-methoxyphenyl)-1-buten-2-one
(2c). Yield 85%, mp: 41–43 ꢁC; IR (KBr) nmax=cmꢀ1: 3445 (OH), 3065, 3015
=
(C CH), 2955 (C C), 1760, 1670 (O C-C C), 1596, 1577 (C-O), 1451, 1353,
=
=
=
1
1279, 1214, 1100, 972; H NMR (400 MHz, CDCl3): d 3.88 (s, 3H, 3-OCH3), 6.79
(s, 1H, H3), 7.13 (m, 1H, Ar), 7.4 (m, 1H, Ar), 7.45 (m, 1H, Ar), 7.50 (m, 1H,
Ar) 14.8 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 186.1 (C2), 180.7 (C4),
159.9, 133.9, 129.9, 119.6, 119.2, 112.2 (Ar), 94.9 (C1), 89.9 (C3), 55.5 (3-OCH3);
MS (70 eV) m=z 298 (Mþ þ 4, 11), 296 (Mþ þ 2, 28), 294 (Mþ, 35), 233 (10), 231
(18), 177 (100), 135 (100), 109 (70), 92 (20), 69 (100). Anal. calcd. for C11H9Cl3O3:
C, 44.70; H, 3.07. Found: C, 44.50; H, 3.0.
1,1,1-Trichloro-4-hydroxy-4-(4-methoxyphenyl)-1-buten-2-one
(2d). Yield 82%, mp: 58–60 ꢁC; IR (KBr) nmax=cmꢀ1: 3437 (OH), 3067 (C CH),
=
=
2936, 2840 (C C), 1602, 1599 (O C-C C), 1562, 1511 (C-O), 1465, 1309, 1251,
=
=
1
1177, 1026; H NMR (400 MHz, CDCl3): d 3.89 (s, 3H, 4-OCH3), 6.75 (s, 1H,
H3), 6.98 (m, 2H, Ar), 7.92 (m, 2H, Ar), 14.6 (s, br, 1H, OH); 13C NMR
(100 MHz, CDCl3): d 185.4 (C2), 181.2 (C4), 164.0, 129.4, 124.7, 114.3 (Ar), 95.0
(C1), 88.3 (C3), 55.5 (4-OCH3); MS (70 eV) m=z 298 (Mþ þ 4, 4), 296 (Mþ þ 2,
10), 294 (Mþ, 10), 233 (10), 231 (15), 177 (100), 135 (85), 109 (20), 92 (20), 69
(30). Anal. calcd. for C11H9Cl3O3: C, 44.70; H, 3.07. Found: C, 44.85; H, 3.1.
1,1,1-Trichloro-4-(4-fluorophenyl)-4-hydroxy-1-buten-2-one (2e). Yield
82%, mp: 75–76 ꢁC; IR (KBr) nmax=cmꢀ1: 3424 (OH), 3072 (C CH), 2966, (C C),
=
=
1594, 1576 (O C-C C), 1508, 1437 (C-O), 1437, 1330, 1230, 1170, 1076; 1H
NMR (400 MHz, CDCl3): d 6.7 (s, 1H, H3), 7.2 (m, 2H, Ar), 7.9 (m, 2H, Ar),
14.3 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 186.1 (C2), 179.7 (C4),
165.9 JCF ¼ 254, 129.7 JCF ¼ 9.2, 128.7 JCF ¼ 3.0, 116.2 JCF ¼ 21.6 (Ar), 94.9 (C1),
89.3 (C3); MS (70 eV) m=z 284 (Mþ þ 2, 2), 282 (Mþ, 2), 221 (5), 219 (12), 165
(100), 123 (70), 95 (30), 69 (35). Anal. calcd. for C10H6Cl3FO2: C, 42.37; H, 2.13.
Found: C, 42.2; H, 2.1.
=
=
1,1,1-Trichloro-4-(4-chlorophenyl)-1-buten-2-one (2f). Yield 86%, mp:
69–71 ꢁC; IR (KBr) nmax=cmꢀ1: 3422 (OH), 3052 (C CH), 2960, (C C), 1646,
=
=
1
=
=
1586, 1583, 1558 (O C-C C), 1486, 1427 (C-O), 1319, 1212, 1092, 1074, 1011; H
NMR (400 MHz, CDCl3): d 6.7 (s, 1H, H3), 7.5 (m, 2H, Ar), 7.8 (m, 2H, Ar),
14.2 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 186.3 (C2), 179.3 (C4),
139.7, 130.9, 129.3, 128.4 (Ar), 94.9 (C1), 89.7 (C3); MS (70 eV) m=z 302 (Mþ þ 4,
4), 300 (Mþ, 6), 298 (4), 239 (2), 237 (5), 235 (8), 183 (25), 181 (100), 139 (70), 111
(20), 69 (35). Anal. calcd. for C10H6Cl4O2: C, 40.04; H, 2.02. Found: C, 40.1; H, 2.0.
4-(4-Bromophenyl)-1,1,1-trichloro-4-hydroxy-1-buten-2-one (2g). Yield
83%, mp: 65–67 ꢁC; IR (KBr) nmax=cmꢀ1: 3422 (OH), 1702, 1646, 1589, 1556
(O C-C C), 1486, 1430 (C-O), 1211, 1186, 1152, 1076, 1011; 1H NMR
=
=

TRICHLOROACETYLACETOPHENONES
735
(400 MHz, CDCl3): d 6.7 (s, 1H, H3), 7.6 (m, 2H, Ar), 7.8 (m, 2H, Ar), 14.2 (s, br,
1H, OH); 13C NMR (100 MHz, CDCl3): d 186.3 (C2), 179.4 (C4), 132.2, 131.3, 128.5,
128.3 (Ar), 94.8 (C1), 89.7 (C3); MS (70 eV) m=z 348 (Mþ þ 4, 1), 346 (Mþ þ 2, 5),
344 (Mþ, 6), 342 (4), 283 (4), 281 (10), 227 (95), 225 (100), 185 (60), 183 (65), 157
(20), 155 (18), 109 (20), 89 (15), 69 (70). Anal. calcd. for C10H6BrCl3O2: C, 34.87;
H, 1.76. Found: C, 34.85; H, 1.90.
4,4,4-Trichloro-4-hydroxy-4-(4,4’-biphenyl)-1-buten-2-one
(2h). Yield
=
76%, mp: 74–76 ꢁC; IR (KBr) nmax=cmꢀ1: 3427 (OH), 3058, 3031 (C CH), 2986,
=
=
2959 (C C), 1680, 1603, 1597, 1589 (O C-C C), 1553, 1513, 1485 (C-O), 1423,
=
1
1402, 1262, 1195, 1120, 1078; H NMR (400 MHz, CDCl3): d 6.85 (s, 1H, H3),
7.45–7.50 (m, 3H, Ph), 7.62–7.67 (m, 2H, Ph), 7.70–7.75 (m, 2H, Ar), 7.99–8.10
(m, 2H, Ar), 14.3 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 186.1 (C2),
180.5 (C4), 146.1, 139.5, 131.2, 129.0, 128.4, 127.7, 127.5, 127.2 (Ar), 95.0 (C1),
89.5 (C3); MS (70 eV) m=z 298 (Mþ þ 4, 4), 296 (Mþ þ 2, 10), 294 (Mþ, 10), 233
(10), 231 (15), 177 (100), 135 (85), 109 (20), 92 (20), 69(30). Anal. calcd. for
C16H11Cl3O2: C, 56.25; H, 3.25. Found: C, 56.5; H, 3.5.
1,1,1-Trichloro-4-hydroxy-4-(4-nitrophenyl)-1-buten-2-one (2i). Yield
78%, mp: 79–82 ꢁC; IR (KBr) nmax=cmꢀ1: 3442 (OH), 3127 (C CH), 2986, 2935
=
=
=
=
(C C), 1652, 1605, 1573 (O C-C C), 1522, 1490 (C-O), 1426, 1341, 1320, 1213,
1
1153, 1073; H NMR (400 MHz, CDCl3): d 6.7 (s, 1H, H3), 8.0 (m, 2H, Ar), 8.2
(m, 2H, Ar), 13.8 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 186.8 (C2),
176.6 (C4), 150.3, 138.0, 128.0, 124.0 (Ar), 94.7 (C1), 91.6 (C3); MS (70 eV) m=z
311 (Mþ þ 2, <1), 309 (Mþ, <1), 248 (2), 246 (5), 192 (100), 150 (40), 104 (15), 89
(10), 69(18). Anal. calcd. for C10H6Cl3NO4: C, 38.68; H, 1.95. Found: C, 38.8; H,
2.0.
1,1,1-Trichloro-4-hydroxy-4-(1-naftyl)-1-buten-2-one (2j). Yield 82%, mp:
74–75 ꢁC; IR (KBr) nmax=cmꢀ1: 3451 (OH), 3029, 3040 (C CH), 1621, 1579 (C O),
1394, 1366, 1325, 1245, 1188, 1145, 839, 779; 1H NMR (400 MHz, CDCl3): d 6.65 (s,
1H, H3), 7.45–7.60 (m, 4H, Ar), 7.77 (m, 1H, Ar), 7.88 (m, 1H, Ar), 7.98 (m, 1H,
Ar), 8.37 (m, 1H, Ar), 14.3 (s, br, 1H, OH); 13C NMR (100 MHz, CDCl3): d 185.7
(C2), 184 (C4), 133.8, 132.8, 131.6, 130, 128.7, 127.9, 127.7, 126.6, 125.1, 124.8
(Ar), 95.0 (C3), 94.9 (CCl3); MS (70 eV) m=z 318 (Mþ þ 4, 6), 316 (Mþ þ 2, 15),
314 (Mþ, 17), 210 (20), 197 (100), 155 (57), 127 (47), 69 (22). Anal. calcd. for
C14H9Cl3O2: C, 53.28; H, 2.87. Found: C, 53.5; H, 2.90.
=
=
1,1,1-Trichloro-4-hydroxy-4-(2-naftyl)-1-buten-2-one (2k). Yield 86%,
mp: 79–81 ꢁC; IR (KBr) nmax=cmꢀ1: 3451 (OH), 3109 (C CH), 1618, 1600, 1584,
=
=
1563 (C O), 1404, 1386, 1398, 1337, 1265, 1190, 1142, 1132, 837, 822, 777, 766;
1H NMR (400 MHz, CDCl3): d 6.97 (s, 1H, H3), 7.63 (m, 2H, Ar), 7.91 (m, 1H,
Ar), 7.94 (m, 1H, Ar), 7.99 (m, 1H, Ar), 8.54 (m, 1H, Ar), 14.4 (s, br, 1H, OH);
13C NMR (100 MHz, CDCl3): d 186.1 (C2), 180.7 (C4), 135.6, 132.6, 129.7, 129.5,
128.8, 128.7, 127.8, 127.1, 122.7 (Ar), 95.1 (C1), 89.9 (C3). Anal. calcd. for
C14H9Cl3O2: C, 53.28; H, 2.87. Found: C, 53.5; H, 2.90.
4,4,4-Trichloro-2-methyl-1-phenylbutan-1,3-dione (2l). Yield 90%, mp:
97–98 ꢁC; IR (KBr) nmax=cmꢀ1: 3059 (C CH), 2983, 2935 (C C), 1810 (C O),
=
=
=

736
A. F. C. FLORES ET AL.
1
=
1715 (C O), 1642, 1495 (C-C), 1398, 1325, 1260, 1239, 1150, 1092, 1015; H NMR
(400 MHz, CDCl3): d 1.63 (d, JHH 7.2Hz, 3H, CH3), 5.41 (q, JHH 7.2Hz, 1H, H2),
7.52 (m, 2H, Ph), 7.63 (m, 1H, Ph), 8.05 (m, 2H, Ph); 13C NMR (100 MHz, CDCl3):
d 194.5 (C2), 186.6 (C4), 134.2, 134.0, 129.1, 128.8, (Ar), 95.8 (CCl3), 47.3 (C3), 16.6
(CH3); MS (70 eV) m=z 161 (13), 105 (100), 77 (30), 51 (8). Anal. calcd. for
C11H9Cl3O2: C, 47.26; H, 3.25. Found: C, 47.5; H, 3.4.
ACKNOWLEDGMENTS
´
Financial support from the Conselho Nacional de Desenvolvimento Cientıfico
´
`
e Tecnologico (CNPq) and the Fundac¸a˜o de Amparo a Pesquisa do Estado do Rio
Grande do Sul (FAPERGS) is acknowledged. All authors thank CNPq for
fellowships.
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