2-Perfluoroalkanoylcyclopentane-1,3-diones. Synthesis and some transformations

Article abstract of DOI:10.1134/S107042801210003X

2-Perfluoroalkanoylcyclopentane-1,3-diones were synthesized for the first time by acylation of cyclopentane-1,3-dione with perfluorocarboxylic acids in the presence of 1,1′-carbonyldiimidazole or with perfluorocarboxylic anhydrides in the presence of imidazole. 2-Perfluoroalkanoylcyclopentane-1,3- diones were selectively reduced to 2-(1-hydroxyperfluoroalkyl)cyclopentane-1,3- diones by the action of triethylsilane in trifluoroacetic acid in the presence of a catalytic amount of lithium perchlorate. Treatment of the title compounds with oxalyl chloride and subsequent reaction with 2 equiv of primary amine (4-fluoroaniline, 4-fluorobenzylamine, 3,4-difluoroaniline, 3- trifluoromethylbenzylamine) gave the corresponding 3-arylamino-2- perfluoroalkanoylcyclopent-2-en-1-ones. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S107042801210003X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 10, pp. 1277–1282. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © T.S. Khlebnikova, Yu.A. Piven’, V.G. Isakova, F.A. Lakhvich, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48,
No. 10, pp. 1283–1288.
2-Perfluoroalkanoylcyclopentane-1,3-diones.
Synthesis and Some Transformations
T. S. Khlebnikova, Yu. A. Piven’, V. G. Isakova, and F. A. Lakhvich
Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus,
ul. Akademika Kuprevicha 5/2, Minsk, 220141 Belarus
e-mail: khlebnicova@iboch.bas-net.by
Received April 30, 2012
Abstract—2-Perfluoroalkanoylcyclopentane-1,3-diones were synthesized for the first time by acylation of
cyclopentane-1,3-dione with perfluorocarboxylic acids in the presence of 1,1′-carbonyldiimidazole or with
perfluorocarboxylic anhydrides in the presence of imidazole. 2-Perfluoroalkanoylcyclopentane-1,3-diones were
selectively reduced to 2-(1-hydroxyperfluoroalkyl)cyclopentane-1,3-diones by the action of triethylsilane in
trifluoroacetic acid in the presence of a catalytic amount of lithium perchlorate. Treatment of the title
compounds with oxalyl chloride and subsequent reaction with 2 equiv of primary amine (4-fluoroaniline, 4-
fluorobenzylamine, 3,4-difluoroaniline, 3-trifluoromethylbenzylamine) gave the corresponding 3-arylamino-2-
perfluoroalkanoylcyclopent-2-en-1-ones.
DOI: 10.1134/S107042801210003X
Fluorinated derivatives of β-di- and β-triketones
constitute an interesting class of compounds; in many
cases these compounds are superior to non-fluorinated
analogs in useful properties. They are used as ligands
for catalysts in various reactions, metal extractants,
analytical reagents, etc. [1], and the presence of reac-
tive carbonyl groups in their molecules makes them
effective reagents in the synthesis of biologically
active compounds. Introduction of fluorine atoms into
organic molecules produces considerable variation of
their chemical and physical properties [2]. Replace-
ment of hydrogen by fluorine often enhances bio-
logical activity of organic compounds as a result of
increase of their lipophilicity and change of steric and
electronic properties [3]. Polyfunctional 2-perfluoro-
alkanoylcyclocyclopentane-1,3-diones are promising
as building blocks for the synthesis of various poly-
fluoroalkyl-containing compounds. Non-fluorinated
β-triketones of the cyclopentane series are widespread
in nature, as well as among synthetic biologically ac-
tive compounds [4]; they are also used as intermediates
in the synthesis of other natural compounds and related
physiologically active substances [5]. However, unlike
non-fluorinated analogs, neither methods of synthesis
of perfluoroalkanoyl-substituted β-diketones of the
cyclopentane series nor their reactions have been
reported so far.
The goal of the present work was to develop
a procedure for the synthesis of 2-perfluoroalkanoyl-
cyclopentane-1,3-diones and examine their chemical
transformations. Our attempts to obtain 2-perfluoroal-
kanoylcyclopentane-1,3-diones according to the proce-
dure commonest for their fluorine-free analogs, i.e., by
O–C-isomerization of 3-oxocyclopent-1-enyl carbox-
ylates in the presence of different catalysts (AlCl3,
acetone cyanohydrin), were unsuccessful. The most
efficient method for the synthesis of cyclopentane
β-triketones having a perfluorinated aliphatic acyl side
chain is based on acylation of cyclopentane-1,3-dione
(I) with perfluorocarboxylic acids in the presence of
1,1′-carbonyldiimidazole or with perfluorocarboxylic
anhydrides in the presence of imidazole in chloroform.
Presumably, the reaction of perfluorocarboxylic
acids with 1,1′-carbonyldiimidazole or of their anhy-
drides with imidazole gives N-perfluoroacylimidazoles
that are efficient acylating agents [6, 7]; the latter react
with cyclopentane-1,3-dione (I) in the presence of
imidazole, yielding 2-perfluoroalkanoylcyclopentane-
1,3-diones with high yield and regioselectivity. By
reactions of perfluoropropionic and perfluorobutyric
acids with 1,1′-carbonyldiimidazole in chloroform, fol-
lowed by treatment of N-perfluoroacylimidazole thus
obtained with a solution of cyclopentane-1,3-dione (I)
and imidazole in chloroform (4 h, room temperature),
1277

KHLEBNIKOVA et al.
1278
Scheme 1.
O
O
OH
RF
O
RF
O
OH
OH
IIa–IIc
O
O
O
O
O
Et3SiH, TFA
LiClO4
OH
RF
OH
RF
O
i or ii
RF
O
O
O
I
IIIa–IIIc
O
O
O
(COCl)2
RNH2
RF
RF
Cl
NHR
IVa–IVf
i: RFCOOH, 1,1′-carbonyldiimidazole; ii: (RFCO)2O, imidazole; II, III, RF = CF3 (a), C2F5 (b), C3F7 (c); IV, RF = CF3, R =
4-FC6H4 (a); RF = C2F5, R = 4-FC6H4 (b); RF = C3F7, R = 4-FC6H4 (c), 3,4-F2C6H3 (d), 4-FC6H4CH2 (e), 3-CF3C6H4CH2 (f).
we obtained β-triketones IIb and IIc in 91 and 90%
yield, respectively. Alternatively, trifluoroacetic and
perfluoropropionic anhydrides reacted with imidazole
in chloroform at 0°C, and the subsequent treatment of
intermediate N-perfluoroacylimidazole with a solution
of cyclopentane-1,3-dione (I) and imidazole in chloro-
form (3 h, room temperature) afforded β-triketones IIa
and IIb in 90 and 92% yield, respectively (Scheme 1).
tions of ionic hydrogenation [8]. It is known that ionic
hydrogenation of non-fluorinated 2-acylcyclopentane-
1,3-diones is regioselective; it results in reduction of
the side-chain carbonyl group to methylene with
formation of 2-alkylcyclopentane-1,3-diones [9]. This
transformation was successfully used in syntheses of
prostaglandins [10] and phytoprostanes [11]. Treat-
ment of compounds IIa−IIc with triethylsilane in tri-
fluoroacetic acid in the presence of lithium perchlorate
at room temperature (reaction time 5 h) led to selective
formation of 2-(1-hydroxyperfluoroalkyl)cyclopen-
tane-1,3-diones IIIa–IIIc in 82−89% yield. According
to spectral data, diketo alcohols IIIa–IIIc, like their
cyclohexane analogs [12], exist in the enol form. Their
IR spectra contained absorption bands at 1615 and
1555 cm−1 due to vibrations of conjugated carbonyl
group and double bond, respectively, whereas no ab-
sorption bands were present in the region 1720−
1740 cm−1. In the 13C NMR spectrum of trifluoroethyl
derivative IIa, the COH carbon atom resonated as
a quartet at δC 67.1 ppm (2JCF = 34 Hz), and the corre-
sponding signals in the spectra of pentafluoropropyl
and hexafluorobutyl analogs IIb and IIc appeared,
The presence of a β-tricarbonyl fragment in mole-
cules IIa−IIc implies the possibility for keto–enol
tautomerism with formation of structures differing by
the position of the enol fragment (endo- or exocyclic)
with strong intramolecular hydrogen bond. Analysis of
the spectral data (IR, NMR) showed that triketones
IIa−IIc, as well as their nonfluorinated analogs, are
completely enolized [5]. The IR spectra of IIa−IIc
lacked absorption in the region 1720−1740 cm−1,
which is typical of free carbonyl group, but a band at
1705 cm−1 was present due to conjugated carbonyl
group; in addition, absorption bands at 1640−1655
(carbonyl group involved in H-chelate ring) and
1570−1565 cm−1 (C=C) were observed. Compounds
1
IIa−IIc displayed in the H NMR spectra a broadened
respectively, as a doublet of doublets at δC 66.6 (JCF
=
29, 24 Hz) and a triplet at δC 67.1 ppm (2JCF = 27 Hz).
The fluorine signal in the 19F NMR spectrum of IIa
was a doublet at δF –79.62 ppm (3JFH = 6.4 Hz). The
19F NMR spectra of IIb and IIc were complicated due
to magnetic nonequivalence of CF2 fluorine atoms.
singlet at δ ~13 ppm due to enolic hydroxy proton; the
corresponding proton in cyclohexane analogs reso-
nated in a weaker field [7].
We examined transformations of 2-perfluoroal-
kanoylcyclopentane-1,3-diones IIa–IIc under condi-
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2-PERFLUOROALKANOYLCYCLOPENTANE-1,3-DIONES.
1279
Molecules of 2-perfluoroalkanoylcyclopentane-1,3-
diones II possess three electrophilic centers capable of
undergoing attack by nucleophiles. With a view to
obtain new fluoroalkyl derivatives, we examined the
reactivity of compounds IIa−IIc toward nitrogen-cen-
tered nucleophiles (4-fluoroaniline, 4-fluorobenzyl-
amine, 3,4-difluoroaniline, and 3-trifluoromethylben-
zylamine). Non-fluorinated 2-acylcyclopentane-1,3-di-
ones existing in the enol form are fairly strong vinylo-
gous acids which readily react with N-nucleophiles at
the exocyclic carbonyl group [5] to produce the corre-
sponding enamino derivatives. However, treatment of
2-perfluoroalkanoylcyclopentane-1,3-diones IIa–IIc
with the above primary amines resulted in the forma-
tion of complex mixtures of products; reactions of their
cyclohexane analogs with primary amines were ac-
companied by loss of the perfluoroacyl group, and the
products were the corresponding 3-aminocyclohex-2-
en-1-ones [13].
in the 19F NMR spectrum of IVa was typical of tri-
fluoroacetyl group. Signals from side-chain fluorine
atoms in the spectra of the other enamines were ob-
served at δF, ppm: –81.4 s (CF3), –120.8 s (CF2) (IVb);
–80.4 to −80.5 s (CF3), –117.2 s (CF2), –125.1 to
−125.2 s (CF2) (IVc–IVf).
EXPERIMENTAL
The 1H, 13C, and 19F NMR spectra were recorded at
293 K on a Bruker-Biospin Avance 500 spectrometer
operating at 500.13, 125.77, and 470 MHz, respec-
tively, using a 5-mm QNP probe (z-gradient) from
solutions in CDCl3 (unless otherwise stated); the
chemical shifts were determined relative to the residual
proton or carbon signal of the solvent (δ 7.26 ppm,
δC 77.16 ppm) or trifluoromethylbenzene (external
reference; δF −63 ppm). The melting points were
measured on a Boetius melting point apparatus. The
elemental compositions were determined on a Euro-
vector EA3000 CHNS-O analyzer. The progress of
reactions was monitored, and the purity of products
was checked, by TLC on Silufol UV-254 plates using
ethyl acetate–hexane as eluent.
Enamino derivatives of compounds IIa–IIc at the
endocyclic carbonyl group were obtained by nucleo-
philic substitution in their enol derivatives (chlorovinyl
diketones). For this purpose, triketones IIa–IIc were
treated with oxalyl chloride (4 h, room temperature),
and 3-chloro-2-perfluoroacylcyclopent-2-en-1-ones
obtained after removal of the chlorinating agent under
reduced pressure were brought into reaction with
2 equiv of primary amine (4-fluoroaniline, 4-fluoro-
benzylamine, 3,4-difluoroaniline, and 3-trifluoro-
methylbenzylamine; reaction time 1 h). The target
enamino derivatives IVa–IVf were isolated in 68−90%
yield (Scheme 1).
Acylation of cyclopentane-1,3-dione (general
procedures). a. With perfluorocarboxylic acids. A solu-
tion of 40 mmol of pentafluoropropionic or hepta-
fluorobutyric acid in 30 ml of anhydrous chloroform
was added dropwise at room temperature to a solution
of 20 mmol (3.24 g) of 1,1′-carbonyldiimidazole in
50 ml of anhydrous chloroform. A solution of 10 mmol
(0.98 g) of cyclopentane-1,3-dione and 10 mmol
(0.68 g) of imidazole in 100 ml of anhydrous chloro-
form was added dropwise to the resulting suspension,
and the mixture was stirred for 4 h at room temperature
and washed with a dilute (1:10) solution of hydro-
chloric acid (3×50 ml) and a saturated solution of
sodium chloride (50 ml). The organic phase was dried
over MgSO4, the aqueous phase was extracted with
ethyl acetate (3×50 ml), the extracts were combined
with the organic phase, washed with a saturated solu-
tion of sodium chloride NaCl (40 ml), and dried over
MgSO4, the solvent was removed under reduced pres-
sure, and the residue was dried in a vacuum to obtain
compound IIb or IIc as colorless crystals.
The IR spectra of IVa–IVf contained absorption
bands at 1695−1705 and 1640–1645 cm−1 due to
stretching vibrations of the conjugated endo- and exo-
1
cyclic carbonyl groups, respectively. In the H NMR
spectra of IVa–IVf we observed signals from methy-
lene protons and signals at δ 10.47–11.67 ppm from
the NH proton involved in strong intramolecular
hydrogen bond with the carbonyl group. Compounds
IVa–IVf displayed in the 13C NMR spectra signals
from the endocyclic carbonyl carbon atom
(δC 195.3−196.2) and carbon atom linked to the NH
group (δC 183.6−184.4 ppm). The exocyclic carbonyl
carbon atom in the 13C NMR spectrum of trifluoro-
acetyl derivative IVa resonated as a quartet at
δ 176.8 ppm (2JCF = 39 Hz), and the corresponding
signal in the spectra of pentafluoropropionyl and
heptafluorobutanoyl derivatives was a triplet at
δC 179.7 (2JCF = 30 Hz; IVb) or 179.2−180.1 ppm
(JCF 29−30 Hz; IVc–IVe). The singlet at δF –76.1 ppm
b. With perfluorocarboxylic anhydrides. A solution
of 20 mmol (1.36 g) of imidazole in 50 ml of anhy-
drous chloroform was cooled to 0°C, a solution of
10 mmol of trifluoroacetic or pentafluoropropionic
anhydride in 30 ml of anhydrous chloroform was
added dropwise, and a solution of 5 mmol (0.49 g) of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 10 2012

KHLEBNIKOVA et al.
1280
cyclopentane-1,3-dione and 5 mmol (0.34 g) of imid-
azole in 70 ml of anhydrous chloroform was added
dropwise. The mixture was stirred for 3 h at room
temperature and washed with a solution of HCl (1:10;
3×50 ml) and a saturated solution of sodium chloride
(50 ml). The organic phase was dried over MgSO4, the
aqueous phases were extracted with ethyl acetate
(3×50 ml), the extracts were combined, washed with
a saturated solution of sodium chloride (40 ml), and
dried over MgSO4, the solvent was removed under
reduced pressure, and the residue was dried in
a vacuum. Compounds IIa and IIb were isolated as
colorless crystals.
(4×4 ml) and dissolved in diethyl ether, and the solu-
tion was filtered. The solvent was removed under
reduced pressure, and the residue (compound IIIa–
IIIc) was recrystallized from diethyl ether–hexane.
2-(2,2,2-Trifluoro-1-hydroxyethyl)cyclopentane-
1,3-dione (IIIa). Yield 82%, mp 113–116°C. IR spec-
1
trum, ν, cm–1: 1615, 1555. H NMR spectrum
(acetone-d6), δ, ppm: 2.59 s (4H, CH2), 4.87 m (1H,
CHOH). 13C NMR spectrum (acetone-d6), δC, ppm:
32.0, 67.1 q (2JCF = 34 Hz), 111.1, 126.7 q (1JCF
=
283 Hz), 199.7 br.s. 19F NMR spectrum (acetone-d6):
δF –79.62 ppm, d (3JFH = 6.4 Hz). Found, %: C 42.88;
H 3.62. C7H7F3O3. Calculated, %: C 42.87; H 3.60.
2-Trifluoroacetylcyclopentane-1,3-dione (IIa).
2-(2,2,3,3,3-Pentafluoro-1-hydroxypropyl)cyclo-
Yield 92% (b), mp 83–86°C. IR spectrum, ν, cm–1:
pentane-1,3-dione (IIIb). Yield 85%, mp 109–112°C.
1
1
IR spectrum, ν, cm–1: 1615, 1555. H NMR spectrum
1705, 1655, 1605. H NMR spectrum, δ, ppm: 2.78 s
(4H, CH2). 13C NMR spectrum (acetone-d6), δC, ppm:
(acetone-d6), δ, ppm: 2.61 s (4H, CH2), 5.03 d.d (1H,
CHOH, J = 20.6, 6.0 Hz). 13C NMR spectrum
(acetone-d6), δC, ppm: 32.1, 66.6 d.d (JCF = 29, 24 Hz),
32.5, 113.1, 117.7 q (1JCF = 287 Hz), 179.7 q (2JCF
=
40 Hz), 201. 9, 202. 0. 19F NMR spectrum:
δF –77.4 ppm, s (CF3). Found, %: C 43.30; H 2.58.
C7H5F3O3. Calculated, %: C 43.31; H 2.60.
2
110.8, 115.8 t.q (1JCF = 255, JCF = 35 Hz), 121.2 q.t
2
(1JCF = 286, JCF = 36 Hz), 199.8 br.s. 19F NMR spec-
2-Pentafluoropropanoylcyclopentane-1,3-dione
(IIb). Yield 91 (a), 90% (b), mp 117–119°C. IR spec-
trum, ν, cm–1: 1705, 1640, 1570. 1H NMR spectrum, δ,
ppm: 2.77 s (4H, CH2), 13.04 br.s (1H, OH). 13C NMR
trum (aceton-d6), δF, ppm: –82.7 s (CF3), –123.1 d.d
2
3
2
(1F, JFF = 272, JFH = 6 Hz), –130.6 d.d (1F, JFF
273, JFH = 20 Hz). Found, %: C 39.09; H 2.91.
=
3
C8H7F5O3. Calculated, %: C 39.04; H 2.87.
spectrum (acetone-d6), δC, ppm: 32.6, 109.1 t.q (1JCF
268, 2JCF = 36 Hz), 114.3, 120.2 q.t (1JCF = 287, 2JCF
=
=
2-(2,2,3,3,4,4,4-Heptafluoro-1-hydroxybutyl)cy-
clopentane-1,3-dione (IIIc). Yield 89%, mp 93–96°C.
34 Hz), 182.8 t (2JCF = 30 Hz), 201.7 br.s. 19F NMR
spectrum, δF, ppm: –82.4 s (CF3), –122.5 s (CF2).
Found, %: C 39.33; H 2.06. C8H5F5O3. Calculated, %:
C 39.36; H 2.06.
1
IR spectrum, ν, cm–1: 1615, 1555. H NMR spectrum
(acetone-d6), δ, ppm: 2.60 s (4H, CH2), 5.10 d.d (1H,
CHOH, J = 22.6, 2.7 Hz). 13C NMR spectrum
(acetone-d6), δC, ppm: 32.1, 67.1 t (2JCF = 27 Hz),
2-Heptafluorobutanoylcyclopentane-1,3-dione
110.6, 111.5 t.m (1JCF = 265 Hz), 117.4 t.m (1JCF
=
2
(IIc). Yield 90% (a), mp 76–78°C. IR spectrum, ν,
256 Hz), 119.9 q.t (1JCF = 287, JCF = 34 Hz),
1
cm–1: 1705, 1640, 1565. H NMR spectrum, δ, ppm:
198.7 br.s. 19F NMR spectrum (acetone-d6), δF, ppm:
2.77 s (4H, CH2), 13.45 br.s (1H, OH). 13C NMR spec-
–82.0 t (3F, CF3, J = 194 Hz), –120.1 d (1F, J =
2
2
trum (acetone-d6), δF, ppm: 32.6, 110.7 t.t (1JCF = 268,
279 Hz), –126.0 d (1F, 2J = 282 Hz), –128.1 d (1F, 2J =
280 Hz), –128.2 d (1F, J = 282 Hz). Found, %:
2JCF = 32 Hz), 111.3 t.m (1JCF = 268 Hz), 114.8,
2
2
119.6 q.t (1JCF = 287, JCF = 33 Hz), 183.1 t (2JCF
=
C 36.48; H 2.36. C9H7F7O3. Calculated, %: C 36.50;
H 2.38.
27 Hz), 201.5, 201.6. 19F NMR spectrum, δF, ppm:
–80.6 s (CF3), –118.9 s (CF2), –125.7 s (CF2). Found,
%: C 36.78; H 1.74. C9H5F7O3. Calculated, %:
C 36.75; H 1.71.
Enamino diketones IVa–IVf (general procedure).
Oxalyl chloride, 5 ml, was added to 2 mmol of
triketone IIa–IIc, and the mixture was stirred for 4 h.
Excess oxalyl chloride was removed under reduced
pressure, the residue was dissolved in 25 ml of chloro-
form, 4 mmol of the corresponding amine was added,
and the mixture was stirred for 1 h, washed with water
(8 ml), and dried over MgSO4. The solvent was
removed under reduced pressure, and the residue was
subjected to chromatography to isolate compound
IVa–IVf as colorless crystals.
Reduction of 2-perfluoroalkanoylcyclopentane-
1,3-diones IIa–IIc (general procedure). Triketone
IIa–IIc, 1 mmol, was dissolved in 2 ml of trifluoro-
acetic acid, 2 ml of a 1% solution of lithium perchlo-
rate in trifluoroacetic acid and 4 mmol of triethylsilane
were added, and the mixture was stirred for 5 h at
room temperature. The solvent was removed under
reduced pressure, the residue was ground with hexane
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2-PERFLUOROALKANOYLCYCLOPENTANE-1,3-DIONES.
1281
2
2
253, JCF = 13 Hz), 150.6 d.d (1JCF = 253, JCF
=
3-(4-Fluorophenylamino)-2-(trifluoroacetyl)cy-
13 Hz), 180.1 t (2JCF = 30 Hz), 183.6, 195.3. 19F NMR
spectrum, δF, ppm: –80.5 s (CF3), –117.2 s (CF2),
–125.1 s (CF2), –132.8 s (1F), –135.8 s (1F). Found,
%: C 44.39; H 1.95; N 3.40. C15H8F9NO2. Calculated,
%: C 44.46; H 1.99; N 3.46.
clopent-2-en-1-one (IVa). Yield 88%, mp 146–149°C.
1
IR spectrum, ν, cm–1: 1705, 1640. H NMR spectrum,
δ, ppm: 2.52 m (2H, CH2), 2.80 m (2H, CH2), 7.20 m
(2H, Harom), 7.30 m (2H, Harom), 11.52 br.s (1H, NH).
13C NMR spectrum, δC, ppm: 25.9, 33.5, 107.4,
116.3 q (1JCF = 287 Hz), 117.1 d (2JCF = 23 Hz),
126.9 d (3JCF = 9 Hz), 131.9 d (3JCF = 2 Hz), 162.1 d
(1JCF = 250 Hz), 176.8 q (2JCF = 39 Hz), 183.9, 196.2.
19F NMR spectrum, δF, ppm: –76.1 s (3F, CF3),
–111.9 s (1F). Found, %: C 54.40; H 3.19; N 4.84.
C13H9F4NO2. Calculated, %: C 54.36; H 3.16; N 4.88.
3-(4-Fluorobenzylamino)-2-(heptafluorobuta-
noyl)cyclopent-2-en-1-one (IVe). Yield 68%, mp 66–
69°C. IR spectrum, ν, cm–1: 1705, 1640. H NMR
1
spectrum, δ, ppm: 2.52 m (2H, CH2), 2.84 m (2H,
CH2), 4.61 d (2H, CH2, J = 6 Hz), 7.11 m (2H, Harom),
7.28 m (2H, Harom), 10.47 br.s (1H, NH). 13C NMR
spectrum, δC, ppm: 25.0, 33.3, 47.8, 108.5, 109.6 t
3-(4-Fluorophenylamino)-2-(pentafluoropro-
panoyl)cyclopent-2-en-1-one (IVb). Yield 90%,
mp 130–133°C. IR spectrum, ν, cm–1: 1705, 1640.
1H NMR spectrum, δ, ppm: 2.51 m (2H, CH2), 2.80 m
(2H, CH2), 7.20 m (2H, Harom), 7.30 m (2H, Harom),
11.61 br.s (1H, NH). 13C NMR spectrum, δC, ppm:
(1JCF = 268, JCF = 32 Hz), 109.7 t.m (1JCF = 268 Hz),
2
116.4 d (2JCF = 21 Hz), 117.9 q.t (1JCF = 288, JCF
=
=
2
33 Hz), 129.2 d (3JCF = 8 Hz), 130.4, 162.9 d (1JCF
248 Hz), 179.2 t (2JCF = 29 Hz), 184.1, 195.3.
19F NMR spectrum, δF, ppm: –80.5 s (CF3), –112.8 s
(1F), –117.1 s (CF2), –125.1 s (CF2). Found, %:
C 47.92; H 2.74; N 3.48. C16H11F8NO2. Calculated, %:
C 47.89; H 2.76; N 3.49.
2
26.0, 33.5, 107.9 t.q (1JCF = 268, JCF = 36 Hz), 108.6,
2
117.1 d (2J = 23 Hz), 118.5 q.t (1JCF = 287, JCF
=
34 Hz), 126.9 d (3JCF = 9 Hz), 131.9 d (3JCF = 2 Hz),
162.2 d (1JCF = 250 Hz), 179.7 t (2JCF = 30 Hz), 184.1,
195.8. 19F NMR spectrum, δF, ppm: –81.4 s (3F, CF3),
–112.0 s (1F), –120.8 s (2F, CF2). Found, %: C 49.90;
H 2.71; N 4.12. C14H9F6NO2. Calculated, %: C 49.86;
H 2.69; N 4.15.
2-(Heptafluorobutanoyl)-3-[(3-trifluoromethyl)-
benzylamino]cyclopent-2-en-1-one (IVf). Yield 88%,
mp 79–82°C. IR spectrum, ν, cm–1: 1695, 1645.
1H NMR spectrum, δ, ppm: 2.54 m (2H, CH2), 2.85 m
(2H, CH2), 4.71 d (2H, CH2, J = 6 Hz), 7.51 m (1H,
H
arom), 7.58 m (1H, Harom), 7.66 m (2H, Harom),
10.55 br.s (1H, NH). 13C NMR spectrum, δC, ppm:
3-(4-Fluorophenylamino)-2-(heptafluorobuta-
25.0, 33.3, 47.9, 108.7, 109.0 t.m (1JCF = 267 Hz),
noyl)cyclopent-2-en-1-one (IVc). Yield 80%, mp 97–
1
99°C. IR spectrum, ν, cm–1: 1705, 1640. H NMR
109.6 t.t (1JCF = 267, JCF = 31 Hz), 117.8 q.t (1JCF
=
2
2
288, JCF = 34 Hz), 123.7 q (1JCF = 272 Hz), 124.3 d
(3JCF = 3 Hz), 125.7 d (3JCF = 3 Hz), 130.1, 130.6,
131.5 q (2JCF = 33 Hz), 135.7, 179.3 t (2JCF = 29 Hz),
184.4, 195.4. 19F NMR spectrum, δF, ppm: –63.1 s
(CF3), –80.5 s (CF3), –117.2 s (CF2), –125.2 s (CF2).
Found, %: C 45.28; H 2.48; N 3.07. C17H11F10NO2.
Calculated, %: C 45.25; H 2.46; N 3.10.
spectrum, δ, ppm: 2.51 m (2H, CH2), 2.79 m (2H,
CH2), 7.19 m (2H, Harom), 7.28 m (2H, Harom),
11.66 br.s (1H, NH). 13C NMR spectrum, δC, ppm:
25.9, 33.4, 109.1, 109.6 t.m (1JCF = 268 Hz), 109.7 t.t
2
(1JCF = 268, J = 32 Hz), 117.1 d (2JCF = 23 Hz),
118.9 q.t (1JCF = 288 Hz), 126.9 d (3JCF = 9 Hz), 131.9,
162.2 d (1JCF = 250 Hz), 179.9 t (2JCF = 30 Hz), 183.8,
195.5. 19F NMR spectrum, δF, ppm: –80.4 s (CF3),
–111.8 s (1F), –117.2 s (CF2), –125.1 s (CF2). Found,
%: C 46.56; H 2.36; N 3.60. C15H9F8NO2. Calculated,
%: C 46.53; H 2.34; N 3.62.
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