Steric structure of alkyl 2-aryl(hetaryl)hydrazono-3-fluoroalkyl-3- oxopropionates

Article abstract of DOI:10.1134/S1070428009060013

Steric structure of fluorinated 2-arylhydrazono-3-oxo esters was studied by ¹H, ¹⁹F, and ¹³C NMR spectroscopy and X-ray analysis. It was found that these compounds in the crystalline state and in solutions in acetone-d6, D

Full text of DOI:10.1134/S1070428009060013

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 6, pp. 801–809. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © O.G. Khudina, Ya.V. Burgart, E.V. Shchegol’kov, V.I. Saloutin, O.N. Kazheva, A.N. Chekhlov, O.A. D’yachenko, 2009, published in
Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 6, pp. 819–827.
Dedicated to Full Member of the Russian Academy of Sciences
O.N. Chupakhin on his 75th Anniversary
Steric Structure of Alkyl 2-Aryl(hetaryl)hydrazono-
3-fluoroalkyl-3-oxopropionates
O. G. Khudinaa, Ya. V. Burgarta, E. V. Shchegol’kova, V. I. Saloutina, O. N. Kazhevab,
A. N. Chekhlovb, and O. A. D’yachenkob
a Postovskii Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences,
ul. S. Kovalevskoi 20, Yekaterinburg, 620219 Russia
e-mail: saloutin@ios.uran.ru
b Institute of Chemical Physics Problems, Russian Academy of Sciences, Chernogolovka, Moscow oblast, Russia
Received July 17, 2008
1
Abstract—Steric structure of fluorinated 2-arylhydrazono-3-oxo esters was studied by H, 19F, and 13C NMR
spectroscopy and X-ray analysis. It was found that these compounds in the crystalline state and in solutions in
acetone-d6, DMSO-d6, and CDCl3 exist as Z isomers with the ester fragment involved in intramolecular
hydrogen bond with the hydrazone NH proton. Exceptions are alkyl 2-arylhydrazono-4,4-difluoro-3-oxo-
butanoates which exist in acetone-d6 as mixtures of Z and E isomers, the former prevailing. Unlike fluorinated
analogs, ethyl 2-(4-methylphenyl)hydrazono-3-oxobutanoate in crystal has the structure of E isomer in which
intramolecular hydrogen bond is formed between the NH proton and acetyl carbonyl group. The same com-
pound in acetone-d6, DMSO-d6, and CDCl3 gives rise to a mixture of Z and E isomers, the latter prevailing.
DOI: 10.1134/S1070428009060013
Fluorinated 2-aryl(hetaryl)hydrazono-3-oxo esters
are extensively used in organic synthesis as building
blocks for the preparation of various open-chain and
heterocyclic systems [1–6]. Knowledge of the steric
structure of such compounds is important for planning
syntheses based thereon and predicting their reactivity.
metric isomerism was not studied previously for poly-
fluoroalkyl-containing 2-aryl(hetaryl)hydrazono-3-oxo
esters. Therefore, in addition to esters Ib–Ie, Ig, Ii, and
Ik–In synthesized by us previously [1, 5, 6], we pre-
pared a number of alkyl 2-arylhydrazono-3-fluoro-
alkyl-3-oxopropionates Ia, If, Ih, and Ij by azo cou-
pling of the corresponding fluorinated 3-oxopropi-
We previously found that fluorinated 2-aryl(hetaryl)-
hydrazono-3-oxo esters exist as hydrazone tautomers
stabilized by intramolecular hydrogen bond [1]. It is
well known that aryl(hetaryl)hydrazones could give
rise to isomers differing by the position of the aryl-
(hetaryl)amino group with respect to the double C=N
bond. Geometric isomers of 2-aryl(hetaryl)hydrazono-
3-oxo esters should be fairly stable due to formation of
intramolecular hydrogen bond between the NH proton
in the aryl(hetaryl)hydrazono fragment and carbonyl
oxygen atom. The high strength of intramolecular hy-
drogen bond in these compounds follows from strong
deshielding of the NH proton (δNH ≈ 13 ppm). Intra-
molecular hydrogen bond may involve the ester car-
bonyl group (Z isomer) or carbonyl oxygen atom in the
polyfluoroacyl fragment (E isomer). This type of geo-
X
N
X
N
N
H
O
H
O
N
O
O
2
2
3
1
3
1
R
OAlk
R
OAlk
Z Isomer
Ia–Io
E Isomer
R = HCF2, X = 4-MeC6H4, Alk = Me (a), Et (b); R = CF3,
Alk = Et, X = 4-MeOC6H4 (c), 1,5-dimethyl-3-oxo-2-phenyl-
2,3-dihydro-1H-pyrazol-4-yl (d); R = HCF2CF2, Alk = Me,
X = 4-MeC6H4 (e), 4-MeOC6H4 (f); Alk = Me, X = 4-MeO-
C6H4, R = C3F7 (g), HCF2(CF2)3 (h); R = C4F9: Alk = Me,
X = 4-MeC6H4 (i), 4-Me2NC6H4 (j), 1,5-dimethyl-3-oxo-2-
phenyl-2,3-dihydro-1H-pyrazol-4-yl (k); Alk = Et, X =
4-MeOC6H4 (l), 4-MeC6H4 (m); Alk = Et, X = 4-MeC6H4,
R = C6F13 (n), Me (o).
801

KHUDINA et al.
802
ment and carbonyl oxygen atom in the ester moiety
(Z isomer). The distance O1···H1 is 1.83(2) Å, and the
angles N2H1O1 and C1O1H1 are 134(2) and 101(2)°,
respectively. Molecules Ic in crystal adopt s-cis,s-trans
conformation in which the trifluoromethyl and ethoxy
groups are oriented trans relative to the C(=O)–
C(=NNHAr)–C(=O) fragment. For comparison, X-ray
analysis was also performed for a single crystal of
ethyl 2-(4-methylphenylhydrazono)-3-oxobutanoate
(Io). Unlike trifluoromethyl analog Ic, compound Io
was found to exist as E isomer in which intramolecular
hydrogen bond involves carbonyl oxygen atom of
the acetyl fragment (Fig. 2). The distance O3–H1 is
1.82(2) Å, and the angles N2H1O3 and C3O3H1 are
136(2) and 103(1)°, respectively.
C13
O4
C11
C10
C12
C7
H1
O1
C1
C5
C6
N2
N1
C9
C2
C8
O2
O3
C3
F1
F2
C4
F3
Fig. 1. Structure of the molecule of ethyl 4,4,4-trifluoro-2-
[(4-methoxyphenyl)hydrazono]-3-oxobutanoate (Ic) accord-
ing to the X-ray diffraction data.
Comparison of the IR spectra of ethyl 2-(4-methyl-
phenylhydrazono)-3-oxobutanoate (Io), recorded from
a solution chloroform (c ~0.1 M) and from a crystal-
line sample using a diffuse reflectance accessory
(DRA) revealed some differences in the absorption
region corresponding to carbonyl stretching vibrations,
as well as in the “fingerprint” region. In the IR spec-
trum of crystalline compound Io, carbonyl absorption
bands are broadened in the region 1700–1695 cm–1,
whereas the corresponding bands in the spectrum
recorded from chloroform solution are observed at
1700 and 1680 cm–1. Therefore, we presume that the
structures of ester Io in the crystalline state and in
chloroform solution are not identical.
onates with arenediazonium salts. For comparison,
we also synthesized a nonfluorinated analog, ethyl
2-(4-methylphenyl)hydrazono-3-oxobutanoate (Io).
The goal of the present work was to study steric
structure of fluoroalkyl-containing 2-aryl(hetaryl)hy-
drazono-3-oxo esters with a view to predict their re-
activity. The structure of fluorinated esters Ia–In and
nonfluorinated analog Io was studied by NMR spec-
troscopy and X-ray analysis.
According to the X-ray diffraction data for a single
crystal of ethyl 4,4,4-trifluoro-2-(4-methoxyphenyl-
hydrazono)-3-oxobutanoate (Ic) (Fig. 1), a strong
intramolecular hydrogen bond is formed in its mole-
cules between the NH proton in the hydrazone frag-
Mitchell and Nonhebel [7] previously showed by
1H NMR spectroscopy that methyl and ethyl 2-phenyl-
hydrazono- and 2-(4-chlorophenyl)hydrazono-3-oxo-
butanoates in CDCl3 exist as mixtures of Z and E
isomers, the latter prevailing (60–70%). Analysis of
C12
O3
H1
C11
1
the H and 13C NMR spectra of ester Io in CDCl3 and
C4
C13
N2
(CD3)2CO also revealed the presence of Z and E iso-
mers (two sets of signals were observed in each case).
Signals were assigned to particular isomers taking into
account that intramolecular hydrogen bonding induces
downfield shift of the corresponding carbonyl carbon
atom and neighboring carbon atoms relative to those
belonging to the free carbonyl group. In the 13C NMR
spectrum of ester Io, signals from the H-bonded acetyl
fragment of the E isomer are located in a weaker field
[δ(C3) 197.12, δ(C4) 30.67 ppm] relative to the corre-
sponding signals of the free CH3C=O group in the Z
isomer [δ(C3) 193.51, δ(C4) 26.58 ppm]. On the other
hand, the ester carbonyl carbon atom of the E isomer
(free carbonyl group) resonates in a stronger field
[δ(C1) 164.14 ppm] as compared to the carbon atom in
the H-bonded ester carbonyl group [δ(C1) 165.49 ppm,
C3
C2
C7
C10
C9
N1
C8
C1
O1
O2
C5
C6
Fig. 2. Structure of the molecule of ethyl 2-[(4-methyl-
phenyl)hydrazono]-3-oxobutanoate (Io) according to the
X-ray diffraction data.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

STERIC STRUCTURE OF ALKYL 2-ARYL(HETARYL)HYDRAZONO-...
803
Z isomer]. Analogous downfield shifts of signals from
methyl protons in the acetyl fragment of the E isomer
of Io were observed in the H NMR spectra, whereas
The results of our previous study on the steric
structure of a large series of various trifluoromethyl-
containing 1,2,3-trione 2-arylhydrazones showed [6]
that signals from fluorine nuclei in the trifluoroacetyl
fragment involved in intramolecular hydrogen bonding
with the NH proton in the arylhydrazone fragment
appear in the 19F NMR spectra at δF ~87 ppm in CDCl3
or ~89 ppm in (CD3)2CO and that the free CF3CO
group gives rise to signals at δF ~91 ppm in CDCl3 or
~93 ppm in (CD3)2CO. Comparison of these values
with those found for 2-arylhydrazono-4,4,4-trifluoro-
methyl-3-oxobutanoates Ic and Id indicated that intra-
molecular hydrogen bond therein is formed with par-
ticipation of the ester carbonyl group (Z isomer with
free CF3CO group).
Furthermore, the CF3 signal in the 19F NMR spec-
trum of Ic in CDCl3 was a doublet with a coupling
constant 6JFH of 1 Hz (coupling with the hydrazone NH
proton) which is typical of free CF3C=O group [7, 8].
In the 13C NMR spectrum of the same compound in
CDCl3, the ester C1 signal was split into quartet due to
coupling with fluorine (4JCF = 1.4 Hz). The existence
of such coupling suggests s-cis-s-cis conformation of
the conjugated C=O, C=N, and C=O double bonds;
a different conformation is observed in crystal (Fig. 1).
Presumably, dissolution of compound Ic in CDCl3 is
accompanied by rotation of the trifluoroacetyl group
with respect to the single C2–C3 bond (Z′ conformer).
1
methylene protons in the ethoxy group of the same
isomer resonated in a stronger field. The fraction of the
E isomer in weakly polar CDCl3 was greater (90%)
than in polar (CD3)2CO (62%). In addition, the E
isomer was characterized by downfield position of the
NH proton (δ ~14 ppm) as compared to the Z isomer
(δ ≈ 12 ppm), indicating that the intramolecular hydro-
gen bond in the E isomer is stronger.
Unlike nonfluorinated 2-arylhydrazono-3-oxobuta-
noates, polyfluoroalkyl analogs Ic–In exist in solution
[CDCl3, (CD3)2CO, (CD3)2SO] as a single isomer: their
1H, 19F, and 13C NMR spectra contain only one set of
signals. Exceptions are 2-arylhydrazono-4,4-difluoro-
3-oxobutanoates Ia and Ib which displayed in the
1H and 19F NMR spectra (acetone-d6) two sets of
signals corresponding to Z and E isomers. The signals
were assigned to Z and E isomers on the basis of the
same relations as those noted above for ester Io. In
each case, the Z isomers with H-bonded ester carbonyl
group were characterized by downfield signals from
protons in the alkoxy groups, whereas the correspond-
ing E isomers displayed upfield signals of these pro-
tons. A downfield shift was also observed for the NH
signal of the E isomer (δ ~15 ppm) relative to that of
the Z isomer (δ ~13 ppm).
While studying isomerism in the series of fluorinat-
ed 1,2,3-trione 2-arylhydrazones, we found that signals
from fluorine atoms in the α-position with respect to
the free carbonyl group appear in the 19F NMR spectra
in a weaker field relative to analogous signals from
fluorine atoms in the α-position with respect to the
H-bonded carbonyl group [8]. Following this relation,
more intense fluorine signals in the region δF 35.89–
35.90 ppm in the 19F NMR spectra of compounds Ia
and Ib should be assigned to their Z isomers, and those
located in a stronger field, δF 35.73–35.78 ppm, to the
E isomers.
X
N
X
N
N
H
O
F
N
H
O
Dissolution
O
F
F
F
3
2
2
3
1
1
OAlk
O
OAlk
F
F
Z
Z'
Other polyfluorinated esters Ie–In were assigned
Z or E isomer structure by comparing their 19F NMR
spectra with those reported previously for polyfluoro-
alkyl-containing 1,2,3-trione 2-arylhydrazones [8].
Here, chemical shifts of fluorine atoms at the carbon
atom directly attached to carbonyl group (involved or
not involved in intramolecular hydrogen bond with
the NH proton) were considered. The signal from the
α-fluorine atoms in the H-bonded H(CF2)2CO group is
located at δF 41.0 ppm in the spectra recorded in
(CD3)2CO and CDCl3, while the corresponding signal
from the free H(CF2)2CO group appears at δF 42.2 ppm
in CDCl3 and at δF 43.4 ppm in (CD3)2CO [8]. The
chemical shifts of the α-fluorine atoms in the 19F NMR
The structure of trifluoromethyl-containing ester Ic
was studied by IR spectroscopy. The IR spectra of Ic
were recorded from a crystalline sample (dispersed in
mineral oil) and a 0.1 M solution in chloroform. We
observed no appreciable differences in the carbonyl
absorption patterns (ν 1700 cm–1) and concluded that
ester Ic in solution, as well as in the crystalline state,
has Z configuration. Similarity of the 1H and 13C NMR
spectra of Ic in CDCl3 and (CD3)2CO indicates the
presence of its Z isomer in these solvents.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

KHUDINA et al.
804
Energies, charges on carbonyl carbon atoms, and Fukui
indices of 2-arylhydrazono-3-oxo esters Ia, Ic, If, Ii, and Io
molecular hydrogen bond with the ester carbonyl oxy-
gen atom. Exception are difluoromethyl derivatives Ia
and Ib for which both Z and E isomers were identified
in (CD3)2CO solution, the major isomer having Z con-
figuration. Nonfluorinated ester Io in crystal exists as
E isomer in which intramolecular hydrogen bond is
formed between the NH proton and oxygen atom in the
acetyl fragment. The same compound in (CD3)2CO and
CDCl3 gives rise to a mixture of Z and E isomers, the
latter prevailing.
Charges (Fukui indices
for HOMO/LUMO)
Comp. no.,
isomer
E,
kJ/mol
C3=O
C1=O
0–638.52
0–622.72
0–996.99
0–984.37
–1159.13
–1149.82
–2139.14
–2110.76
0–274.18
0–273.45
0.2503
0.3422
Ia, Z
(0.0206/0.2621) (0.0349/0.2112)
0.2313 0.3719
(0.0580/0.4237) (0.0048/0.0651)
0.2972 0.3537
(0.0041/0.3697) (0.0390/0.2929)
0.2520 0.3740
(0.0621/0.4431) (0.0089/0.0712)
0.2869 0.3507
(0.0199/0.2572) (0.0371/0.2116)
0.2383 0.3840
(0.0575/0.4231) (0.0083/0.0688)
0.2882 0.3545
(0.0247/0.2824) (0.0358/0.1954)
0.2529 0.3726
(0.0485/0.4088) (0.0106/0.0669)
0.3123 0.3442
(0.0155/0.0592) (0.0382/0.3003)
0.2823 0.3742
(0.0469/0.3528) (0.0037/0.0635)
E
We made an attempt to rationalize the observed dif-
ferences in the steric structure of fluorinated and non-
fluorinated 2-arylhydrazono-3-oxo esters on the basis
of quantum-chemical calculations. The energy, charge,
and orbital parameters were calculated for the most
favorable conformers of esters Ia, Ic, If, Ii, and Io
in terms of semiempirical AM1 approximation using
MOPAC 7.10 software [9] (see table). The results
showed that the Z isomers of fluorinated esters Ia, Ic,
If, and Ii are energetically more favorable than their
E isomers: the difference in the enthalpies of formation
amounts to 9.31–28.38 kJ/mol. The corresponding
difference for nonfluorinated analog Io is smaller by
an order of magnitude (0.73 kJ/mol).
Ic, Z
E
If, Z
E
Ii, Z
E
Io, Z
E
Presumably, the Z configuration of fluorinated
2-arylhydrazono-3-oxo esters Ia–In is favored by
weaker proton-acceptor power of the carbonyl oxygen
atom in the polyfluoroacyl group due to stronger
negative inductive effect of polyfluoroalkyl group as
compared to alkoxy. Moreover, it is known that the
negative inductive effect of oxygen atom in alkoxy
group is weaker than its positive mesomeric effect. All
these factors favor intramolecular hydrogen bonding
with participation of the ester carbonyl oxygen atom
and hence Z configuration of esters Ia–In.
spectra of esters Ie and If [δF 42.2 in CDCl3 and
43.9 ppm in (CD3)2CO] fall into the range typical of
tetrafluoropropionyl group not involved in intramolec-
ular hydrogen bond (Z isomer).
According to [8], signals from the α-fluorine atoms
in the free polyfluoroacyl group having more than
three carbon atoms in 1,2,3-trione 2-arylhydrazones
are located at δF ~49.4 ppm in chloroform-d and at
δF 51.5 ppm in acetone-d6. Esters Ig–In displayed in
the 19F NMR spectra signals from the CαF2 group in
the regions δF 49.6–50.5 (CDCl3) and 52.1–52.8 ppm
[(CD3)2CO], i.e., in the regions typical of Z isomers.
Comparison of the 13C NMR spectra of nonafluoro-
propyl derivative Il and trifluoromethyl analog Ic (see
Experimental) whose structure was determined by
X-ray analysis showed similarity in the chemical shifts
of carbon nuclei in the ester fragment; these data
provide an additional support to the Z configuration of
ester Il.
Positive inductive effect of methyl group {σI(Me) =
–0.01 [10]} in nonfluorinated 2-arylhydrazono-3-oxo-
butanoates makes the acetyl oxygen atom preferable
for hydrogen bonding with the NH proton in the aryl-
hydrazone fragment, as compared to the alkoxy group
exhibiting negative inductive effect {σI(OEt) = 0.28
[10]}. Therefore, such esters exist mostly as E isomers.
On the other hand, the energies of formation of the
Z and E isomers of nonfluorinated ester Io are fairly
similar, so that the E isomer can readily be transformed
into the Z isomer, and such transformation is observed
in going from crystalline ester Io to solution in CDCl3
and (CD3)2CO.
Thus the results of our study showed that fluori-
nated 2-arylhydrazono-3-oxo esters Ic–In in the crys-
talline state and in solution [(CD3)2CO, CDCl3] exist
as Z isomers with the NH proton involved in intra-
The presence of the second (E) isomer of 2-aryl-
hydrazono-4,4-difluoro-3-oxobutanoates Ia and Ib in
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

STERIC STRUCTURE OF ALKYL 2-ARYL(HETARYL)HYDRAZONO-...
805
(CD3)2CO is likely to be related to the solvent prop-
erties. Electron-withdrawing carbonyl group in acetone
molecule is capable of competing with the ethoxycar-
bonyl group in Ia and Ib for hydrogen bonding with
the NH proton, which weakens the intramolecular
hydrogen bond in the Z isomer and facilitates its trans-
formation into the E isomer. The fact that Z/E isomer-
ism is observed only for difluoromethyl-containing
compounds Ia and Ib may be rationalized in terms of
weaker negative inductive effect of difluoromethyl
group {σI(HCF2) = 0.28 [10]} as compared to other
fluoroalkyl substituents {σI(CF3) = 0.40, σI(C3F7) ≈
σI(C4F9) = 0.39 [10]}. In addition, the inductive effect
of HCF2 group is comparable to that of ethoxy group,
which makes both carbonyl groups in Ia and Ib cap-
able of binding the NH proton.
3-oxo esters may be expected to exhibit different
reactivities toward nucleophilic reagents. In fact, we
previously found [2] that fluorinated esters react with
ethane-1,2-diamine at the ester group to give the cor-
responding N,N′-ethylenebisamides; in contrast, 2-aryl-
hydrazono-3-oxobutanoates reacted with the same di-
amine to form a “mixed” product as a result of nucleo-
philic attack at the ester group of one molecule and
ketone group of the other.
EXPERIMENTAL
1
The H NMR spectra were recorded on Tesla BS-
567A (100 MHz) and Bruker DRX-400 (400 MHz)
spectrometers using tetramethylsilane as internal refer-
ence; the 19F and 13C NMR spectra were measured
on Tesla BS-587A (19F, 75 MHz, C6F6) and Bruker
DRX-400 instruments (19F, 376 MHz, C6F6; 13C,
100.6 MHz, TMS).
The results of quantum-chemical calculations
showed that the C3 atom in the polyfluoroacyl frag-
ment of the Z and E isomers of fluorinated esters Ia,
Ic, If, and Ii is characterized by the highest Fukui
index in the LUMO, and that the largest positive
charge is localized on the C1 atom in the ester frag-
ment. This means that kinetically controlled reactions
of polyfluoroalkyl-containing 2-arylhydrazono-3-oxo
esters with nucleophiles, other conditions being equal,
should involve the C1 center under charge control or C3
center under orbital control. Analogous charge and
electron density distribution over the C1 and C3 atoms
was found for the E isomer of nonfluorinated ester Io.
However, the ester carbonyl carbon atom in the Z
isomer of Io has the highest Fukui index in the LUMO
and the maximal positive charge.
The IR spectra were recorded on a Specord 75IR or
Perkin–Elmer Spectrum One instrument with Fourier
transform from samples dispersed in mineral oil, using
a diffuse reflectance accessory, or from solutions in
chloroform (c ≈ 0.1 M). The elemental compositions
were determined on Carlo Erba CHN/S-O EA 1108
and Perkin–Elmer 2400 Series II analyzers. Column
chromatography was performed on Merck 60 silica gel
(0.063–0.200 mm) using chloroform as eluent. The
melting points were measured in open capillaries using
a Stuart SMP3 melting point apparatus.
Single crystals of ester Ic were obtained by crys-
tallization from methylene chloride–hexane (4:1). The
X-ray diffraction data were acquired on an Xcalibur 3
diffractometer equipped with a CCD detector [graphite
monochromator, λ(MoKα) = 0.71073 Å, temperature
295(2) K, ψ/ω scanning]. Absorption by the crystal
was taken into account analytically using a multi-
faceted crystal model with the aid of CrysAlis RED
1.171.28c4 software. The structure was solved by the
direct method on the basis of Fourier difference syn-
theses using SHELXS-97 software [11]. The positions
and temperature parameters of non-hydrogen atoms
were refined by the least-squares procedure in full-
matrix anisotropic approximation using SHELXL-97
software [11]. C13H13F3N2O4. M 318.25; rhombic crys-
tals, space group Aba2; a = 15.440(3), b = 26.143(3),
Taking into account the above differences in the
steric structure and energy, charge, and orbital param-
eters, fluorinated and nonfluorinated 2-arylhydrazono-
Ar(Ht)
Ar(Ht)
N
H
N
N
N
H
O
RF
O
OAlk
3
2
2
1
3
1
O
OAlk
RF
O
max
LUMO
max
LUMO
P
δmax
P
δmax
Z Isomer
E Isomer
Ar
N
Ar
N
N
H
H
O
N
2
2
c = 6.939(5) Å; V = 2801.2(8) Å3; Z = 8, dcalc
=
Me
O
1
OEt
3
1
3
1.509 g/cm–3; μ = 0.107 mm–1. Total of 1876 reflec-
tions were measured, 869 of which were independent
(R = 0.037, 230 refined parameters).
O
OEt
Me
O
δmax
max
LUMO
max
LUMO
P
δmax
P
Z Isomer
E Isomer
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

KHUDINA et al.
806
spectrum, δF, ppm: in CDCl3 (Z isomer, 100%): 34.55 d
(HCF2, 2JFH = 54.3 Hz); in (CD3)2CO: Z isomer (85%):
Single crystals of ester Io were obtained by crys-
tallization from methylene chloride. The X-ray diffrac-
tion data were acquired on an Enraf–Nonius CAD-4
diffractometer [graphite monochromator, λ(MoKα) =
0.71073 Å, temperature 295(2) K, ω/2θ scanning]. The
structure was solved by the direct method, followed
by Fourier difference syntheses, using SHELXS-97
software [11] and was refined by the least-squares
procedure in full-matrix anisotropic approximation for
all non-hydrogen atoms using SHELXL-97 software
[11]. The coordinates of hydrogen atoms were deter-
mined experimentally or calculated on the basis of
geometry considerations and were refined in isotropic
approximation. C13H16N2O3. M 248.28; rhombic crys-
tals, space group Pbcm; a = 9.150(2), b = 22.100(4),
2
35.89 d (HCF2, JFH = 54.1 Hz); E isomer (15%):
35.73 d (HCF2, 2JFH = 53.8 Hz); in DMSO-d6: Z isomer
2
(100%): 35.23 d (HCF2, JFH = 53.6 Hz). Found, %:
C 53.48; H 4.42; F 14.00; N 10.12. C12H12F2N2O3. Cal-
culated, %: C 53.34; H 4.48; F 14.06; N 10.37.
Ethyl 4,4-difluoro-2-(4-methylphenylhydra-
zono)-3-oxobutanoate (Ib). Yield 54%, yellow crys-
1
tals, mp 96–97°C. H NMR spectrum, δ, ppm: in
CDCl3 (Z isomer, 100%): 1.42 t (3H, OCH2Me, 3JHH
=
=
3
7.1 Hz), 2.38 s (3H, Me), 4.41 q (2H, OCH2, JHH
2
7.1 Hz), 6.70 t (1H, HCF2, JHF = 54.3 Hz), 7.22–
7.28 m (4H, C6H4), 13.45 s (1H, NH); in (CD3)2CO:
3
Z isomer (90%): 1.36 t (3H, OCH2Me, JHH = 7.1 Hz),
c = 6.680(1) Å; V = 1350.8(4) Å3; Z = 4; dcalc
=
3
2.35 s (3H, Me), 4.37 q (2H, OCH2, JHH = 7.1 Hz),
1.220 g/cm3; μ = 0.088 mm–1. Total of 2060 reflections
were measured, 1109 of which were independent (R =
0.045, 138 refined parameters).
2
6.98 t (1H, HCF2, JHF = 54.1 Hz), 7.28–7.30 m and
7.49–7.52 m (4H, C6H4), 13.13 br.s (1H, NH);
E isomer (10%): 1.35 t (3H, OCH2Me, 3JHH = 7.1 Hz),
3
The complete sets of crystallographic data for com-
pounds Ic and Io were deposited to the Cambridge
Crystallographic Data Centre (entry nos. CCDC
683849 and CCDC 623953, respectively; www.ccdc.-
can.ac.uk/conts/retrieving.html; 12 Union Road, Cam-
bridge CB2 1EZ, UK; e-mail: deposit@ccdc.cam.-
ac.uk).
2.36 s (3H, Me), 4.33 q (2H, OCH2, JHH = 7.1 Hz),
2
6.94 t (1H, HCF2, JHF = 53.8 Hz), 7.31–7.33 m and
7.56–7.58 m (4H, C6H4), 14.54 br.s (1H, NH).
19F NMR spectrum, δF, ppm: in CDCl3: Z isomer
(100%): 34.44 d (HCF2, 2JFH = 54.3 Hz); in (CD3)2CO:
2
Z isomer (90%): 35.90 d (HCF2, JFH = 54.1 Hz);
E isomer (10%): 35.78 d (HCF2, 2JFH = 53.8 Hz).
Fluorinated 2-arylhydrazono-3-oxo esters Ic, Ig, Il,
Im [1], Ib, Ie, Ii [5], Id, and Ik [6] and fluorine-free
compound Io [12] were synthesized according to
known procedures and were purified by column chro-
matography. Newly synthesized esters Ia, If, Ih, and Ij
were characterized by elemental analyses and IR spec-
tra in addition to the NMR data.
Ethyl 4,4,4-trifluoro-2-(4-methoxyphenylhydra-
zono)-3-oxobutanoate (Ic). Yield 60%, yellow crys-
1
tals, mp 130–131°C. H NMR spectrum, δ, ppm: in
CDCl3 (Z isomer, 100%): 1.42 t (3H, OCH2Me, 3JHH
=
=
7.1 Hz), 3.84 s (3H, OMe), 4.40 q (2H, OCH2, 3JHH
7.1 Hz), 6.95–6.99 m and 7.36–7.40 m (4H, C6H4),
13.61 br.s (1H, NH); in (CD3)2CO (Z isomer, 100%):
1.35 t (3H, CH2Me, 3JHH = 6.8 Hz), 3.86 s (3H, OMe),
Methyl 4,4-difluoro-2-(4-methylphenylhydra-
zono)-3-oxobutanoate (Ia). Yield 58%, orange
powder, mp 102–103°C. Diffuse reflectance IR spec-
trum, ν, cm–1: 3130 (NH); 1700, 1680 (C=O); 1590,
3
4.38 q (2H, OCH2, JHH = 6.8 Hz), 7.06–7.10 m and
7.57–7.60 m (4H, C6H4), 13.42 br.s (1H, NH).
13C NMR spectrum, δC, ppm: in CDCl3 (Z isomer,
100%): 55.57 (OMe), 14.02 and 61.64 (OEt), 117.27 q
1
1530 (δNH, C=N, C=C); 1220–1125 (C–F). H NMR
1
(C4, JCF = 292.8 Hz), 115.06, (Co), 118.00 (Cm),
spectrum, δ, ppm: in CDCl3 (Z isomer, 100%): 2.37 s
120.34 (Ci), 134.49 (C2), 158.61 (Cp), 174.41 q (C3,
2JCF = 32.3 Hz), 164.09 q (C1, J = 1.4 Hz); in
(CD3)2CO (Z isomer, 100%): 55.94 (OMe), 14.32 and
2
(3H, Me), 3.95 s (3H, OMe), 6.69 t (1H, HCF2, JHF
=
54.3 Hz), 7.22–7.29 m (4H, C6H4), 13.44 br.s (1H,
NH); in (CD3)2CO: Z isomer (85%): 2.36 s (3H, Me),
1
62.16 (OEt), 118.40 q (C4, JCF = 292.9 Hz), 115.83,
2
3.89 s (3H, OMe), 6.99 t (1H, HCF2, JHF = 54.1 Hz),
(Co), 119.04 (Cm), 121.36 (Ci), 135.77 (C2), 159.59
7.29–7.31 m and 7.50–7.54 m (4H, C6H4), 13.12 br.s
2
(Cp), 174.29 q (C3, JCF = 31.5 Hz), 164.09 (C1).
(1H, NH); E isomer (15%): 2.31 s (3H, Me), 3.85 s
19F NMR spectrum, δF, ppm: in CDCl3 (Z isomer,
2
(3H, OMe), 6.95 t (1H, HCF2, JHF = 53.8 Hz), 7.33–
6
100%): 91.43 d (CF3, JFH = 0.8 Hz); in (CD3)2CO
7.35 m and 7.57–7.59 m (4H, C6H4), 14.58 br.s (1H,
(Z isomer, 100%): 93.78 s (CF3).
NH); in DMSO-d6: 2.32 s (3H, Me), 3.85 s (3H, OMe),
2
7.06 t (1H, HCF2, JHF = 53.6 Hz), 7.24–7.26 m and
Ethyl 2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihy-
dro-1H-pyrazol-4-ylhydrazono)-4,4,4-trifluoro-3-
7.48–7.51 m (4H, C6H4), 12.70 s (1H, NH). 19F NMR
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

STERIC STRUCTURE OF ALKYL 2-ARYL(HETARYL)HYDRAZONO-...
807
Methyl 4,4,5,5,6,6,6-heptafluoro-2-(4-methoxy-
oxobutanoate (Id). Yield 57%, yellow powder,
1
phenylhydrazono)-3-oxohexanoate (Ig). Yield 77%,
mp 158–159°C. H NMR spectrum, δ, ppm: in CDCl3
1
(Z isomer, 100%): 1.39 t (3H, CH2Me, 3JHH = 7.1 Hz),
2.52 s (3H, Me), 3.15 s (3H, NMe), 4.39 q (2H, OCH2,
3JHH = 7.1 Hz), 7.35–7.51 m (5H, C6H5), 13.37 s (1H,
NH); in DMSO-d6 (Z isomer, 100%): 1.30 t (3H,
yellow crystals, mp 95–96°C. H NMR spectrum, δ,
ppm: in CDCl3 (Z isomer, 100%): 3.84 s and 3.93 s
(3H each, OMe), 6.95–6.99 m and 7.34–7.40 m (4H,
C6H4), 13.66 s (1H, NH); in (CD3)2CO (Z isomer,
100%): 3.86 s and 3.90 s (3H each, OMe), 7.07–
7.09 m and 7.56–7.60 m (4H, C6H4), 13.43 s (1H, NH).
19F NMR spectrum, δF, ppm: in CDCl3 (Z isomer,
100%): 37.50 m (2F, 5-F), 49.66 m (2F, 4-F), 81.40 m
(3F, CF3); in (CD3)2CO (Z isomer, 100%): 39.64 m
(2F, 5-F), 52.09 m (2F, 4-F), 81.44 m (3F, CF3).
3
CH2Me, JHH = 7.1 Hz), 2.48 s (3H, Me), 3.20 s (3H,
NMe), 4.31 q (2H, OCH2, 3JHH = 7.1 Hz), 7.38–7.58 m
(5H, C6H5), 13.18 s (1H, NH). 13C NMR spectrum
(DMSO-d6), δC, ppm (Z isomer, 100%): 10.49
(CH2Me), 13.86 (Me), 35.13 (NMe), 61.22 (OCH2),
1
111.42 (C4′), 117.03 q (C4, JCF = 292.7 Hz), 121.23
(C2), 124.94 (Co), 127.60 (Cp), 129.34 (Cm), 133.74
(Ci), 144.04 (C3′), 158.00 (C5′), 162.87 (C1), 172.39 q
Methyl 4,4,5,5,6,6,7,7-octafluoro-2-(4-methoxy-
phenylhydrazono)-3-oxoheptanoate (Ih). Yield 81%,
yellow crystals, mp 82–83°C. Diffuse reflectance IR
spectrum, ν, cm–1: 3110 (NH); 1680 (C=O); 1610,
2
(C3, JCF = 31.3). 19F NMR spectrum (CDCl3):
δF 90.81 ppm, s (CF3, Z isomer, 100%).
1
1515 (δNH, N=N, C=C); 1230–1110 (C–F). H NMR
Methyl 4,4,5,5-tetrafluoro-2-(4-methylphenylhy-
spectrum, δ, ppm: in CDCl3 (Z isomer, 100%): 3.84 s
drazono)-3-oxopentanoate (Ie). Yield 71%, orange
and 3.94 s (3H each, OMe), 6.18 t.t (1H, HCF2, 2JHF
=
1
powder, mp 79–80°C. H NMR spectrum (CDCl3), δ,
3
52.0, JHF = 5.6 Hz), 6.96–6.99 m and 7.36–7.40 m
(4H, C6H4), 13.68 s (1H, NH); in (CD3)2CO (Z isomer,
100%): 3.86 s and 3.90 s (3H each, OMe), 6.78 t.t
ppm (Z isomer, 100%): 2.38 s (3H, Me), 3.93 s (3H,
2
3
OMe), 6.34 t.t (1H, HCF2, JHF = 53.2, JHF = 5.6 Hz),
7.23–7.30 m (4H, C6H4), 13.48 br.s (1H, NH).
19F NMR spectrum (CDCl3), δF, ppm (Z isomer,
2
3
(1H, HCF2, JHF = 51.1, JHF = 5.6 Hz), 7.06–7.10 m
and 7.57–7.61 m (4H, C6H4), 13.40 s (1H, NH); in
DMSO-d6 (Z isomer, 100%): 3.79 s and 3.86 s (3H,
OMe), 7.05–7.07 m and 7.51–7.55 m (4H, C6H4),
2
3
100%): 24.59 d.t (2F, HCF2, JFH = 53.2, JFF
=
7.9 Hz), 42.20 m (2F, 4-F).
Methyl 4,4,5,5-tetrafluoro-2-(4-methoxyphenyl-
hydrazono)-3-oxopentanoate (If). Yield 73%, yellow
powder, mp 100–101°C. Diffuse reflectance IR spec-
trum, ν, cm–1: 3135 (NH); 1700, 1655 (C=O); 1610,
1590, 1520 (δNH, N=N, C=C); 1220–1125 (C–F).
1H NMR spectrum, δ, ppm: in CDCl3 (Z isomer,
100%): 3.85 s and 3.93 s (3H each, OMe), 6.34 t.t (1H,
2
3
7.08 (1H, HCF2, JHF = 50.2, JHF = 5.6 Hz), 12.97 s
(1H, NH). 19F NMR spectrum, δF, ppm: in CDCl3
(Z isomer, 100%): 24.41 d.m (2F, HCF2, JFH
2
=
53.0 Hz), 32.38 m (2F, 6-F), 39.20 m (2F, 5-F), 50.09 m
(2F, 4-F); in (CD3)2CO (Z isomer, 100%): 25.60 d.m
(2F, HCF2, 2JFH = 51.1 Hz), 34.69 m (2F, 6-F), 41.96 m
(2F, 5-F), 52.53 m (2F, 4-F); in DMSO-d6 (Z isomer,
100%): 24.34 d.m (2F, HCF2, 2JFH = 50.2 Hz), 33.88 m
(2F, 6-F), 40.99 m (2F, 5-F), 51.33 m (2F, 4-F). Found,
%: C 41.50; H 2.65; F 34.80; N 6.38. C15H12F8N2O4.
Calculated, %: C 41.30; H 2.77; F 34.84; N 6.42.
2
3
HCF2, JHF = 53.2, JHF = 5.6 Hz), 6.97–6.99 m and
7.34–7.36 m (4H, C6H4), 13.60 s (1H, NH); in
(CD3)2CO (Z isomer, 100%): 3.86 s and 3.89 s (3H
2
3
each, OMe), 6.72 t.t (1H, HCF2, JHF = 52.7, JHF
=
5.8 Hz), 7.06–7.10 m and 7.54–8.01 m (4H, C6H4),
13.35 br.s (1H, NH); in DMSO-d6 (Z isomer, 100%):
3.78 s and 3.86 s (3H each, OMe), 6.84 t.t (1H, HCF2,
Methyl 4,4,5,5,6,6,7,7,7-nonafluoro-2-(4-methyl-
phenylhydrazono)-3-oxoheptanoate (Ii). Yield 72%,
1
3
2JHF = 52.0, JHF = 5.6 Hz), 7.05–7.09 m and 7.50–
pale yellow powder, mp 94–95°C. H NMR spectrum,
7.52 m (4H, C6H4), 12.94 br.s (1H, NH). 19F NMR
δ, ppm: in CDCl3 (Z isomer, 100%): 2.38 s (3H, Me),
3.94 s (3H, OMe), 7.23–7.32 m (4H, C6H4), 13.55 s
(1H, NH); in (CD3)2CO (Z isomer, 100%): 2.36 s (3H,
Me), 3.91 s (3H, OMe), 7.32–7.35 m and 7.50–7.52 m
(4H, C6H4), 13.30 s (1H, NH). 19F NMR spectrum
[(CD3)2CO], δF, ppm (Z isomer, 100%): 38.92 m (2F,
6-F), 43.39 m (2F, 5-F), 52.77 m (2F, 4-F), 82.80 m
(3F, CF3).
spectrum, δF, ppm: in CDCl3 (Z isomer, 100%):
2
3
24.45 d.t (2F, HCF2, JFH = 53.2, JFF = 7.7 Hz),
42.23 m (2F, 4-F); in (CD3)2CO (Z isomer, 100%):
2
3
24.47 d.t (2F, HCF2, JFH = 52.7, JFF = 7.7 Hz),
43.94 m (2F, 4-F); in DMSO-d6 (Z isomer, 100%):
2
3
25.84 d.t (2F, HCF2, JFH = 52.0, JFF = 8.0 Hz),
43.56 m (2F, 4-F). Found, %: C 46.60; H 3.72;
F 22.80; N 8.30. C13H12F4N2O4. Calculated, %:
C 46.44; H 3.60; F 22.60; N 8.33.
Methyl 4,4,5,5,6,6,7,7,7-nonafluoro-2-(4-dimeth-
ylaminophenylhydrazono)-3-oxoheptanoate (Ij).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009

KHUDINA et al.
808
Yield 59%, red powder, mp 110–111°C. IR spectrum
(mineral oil), ν, cm–1: 3080 (NH); 1680 sh, 1675
(C=O); 1600, 1585, 1525 (δNH, C=N, C=C); 1225–
1595, 1530 (δNH, C=N, C=C); 1240–1120 (C–F).
1H NMR spectrum (CDCl3), δ, ppm: 1.42 t (3H,
3
CH2Me, JHH = 7.0 Hz), 2.37 s (3H, Me), 4.40 q (2H,
1
3
1100 (C–F). H NMR spectrum (CDCl3), δ, ppm
OCH2, JHH = 7.0 Hz), 7.22–7.31 m (4H, C6H4),
13.55 br.s (1H, NH). 19F NMR spectrum (CDCl3), δF,
ppm: 35.73 m (2F, 8-F), 39.12 m (2F, 7-F), 40.57 m
(2F, 6-F), 41.89 m (2F, 5-F), 50.34 m (2F, 4-F),
81.01 m (3F, CF3). Found, %: C 39.40; H 2.31;
F 44.70; N 5.12. C18H13F13N2O3. Calculated, %:
C 39.15; H 2.37; F 44.72; N 5.07.
(Z isomer, 100%): 3.02 s (6H, Me), 3.92 s (3H, OMe),
6.73–6.75 m and 7.31–7.35 m (4H, C6H4), 13.83 s (1H,
NH). 19F NMR spectrum (CDCl3), δF, ppm (Z isomer,
100%): 36.64 m (2F, 6-F), 41.15 m (2F, 5-F), 50.48 m
(2F, 4-F), 80.91 m (3F, CF3). Calculated, %: C 41.13;
H 3.02; F 36.59; N 8.99. C16H14F9N3O3. Found, %:
C 41.12; H 2.90; F 36.47; N 8.68.
Ethyl 2-(4-methylphenylhydrazono)-3-oxobuta-
noate (Io). Yield 65%, orange powder, mp 80–81°C;
published data [12]: mp 75–76°C. Diffuse reflectance
IR spectrum, ν, cm–1: 3050 (NH); 1700, 1695 sh
(C=O); 1625, 1590, 1505 (δNH, C=N, C=C). IR spec-
Methyl 4,4,5,5,6,6,7,7,7-nonafluoro-2-(1,5-di-
methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-
ylhydrazono)-3-oxoheptanoate (Ik). Yield 68%,
1
yellow powder, mp 129–130°C. H NMR spectrum
1
trum (CHCl3), ν, cm–1: 1700, 1680 (C=O). H NMR
(CDCl3), δ, ppm (Z isomer, 100%): 2.49 s (3H, Me),
3.16 s (3H, NMe), 3.91 s (3H, OMe), 7.34–7.52 m
(5H, C6H5), 13.40 s (1H, NH). 19F NMR spectrum
(CDCl3), δF, ppm (Z isomer, 100%): 36.88 m (2F, 6-F),
40.49 m (2F, 5-F), 49.56 m (2F, 4-F), 80.75 m
(3F, CF3).
spectrum, δ, ppm: in CDCl3: Z isomer (10%): 1.44 t
3
(3H, CH2Me, JHH = 7.1 Hz), 2.35 s (3H, C6H4Me),
3
2.49 s (3H, Me), 4.37 q (2H, OCH2, JHH = 7.1 Hz),
7.18–7.20 m and 7.31–7.33 m (4H, C6H4), 12.80 s
(1H, NH); E isomer (90%): 1.40 t (3H, CH2Me, 3JHH
=
Ethyl 4,4,5,5,6,6,7,7,7-nonafluoro-2-(4-methoxy-
7.1 Hz), 2.35 s (3H, C6H4Me), 2.59 s (3H, Me), 4.33 q
(2H, OCH2, JHH = 7.1 Hz), 7.18–7.20 m and 7.31–
3
phenylhydrazono)-3-oxoheptanoate (Il). Yield 80%,
1
orange powder, mp 77–78°C. H NMR spectrum
7.33 m (4H, C6H4), 14.90 s (1H, NH); in (CD3)2CO:
3
[(CD3)2CO], δ, ppm (Z isomer, 100%): 1.35 t (3H,
Z isomer (38%): 1.31 t (3H, CH2Me, JHH = 7.1 Hz),
CH2Me, 3JHH = 7.0 Hz), 3.84 s (3H, OMe), 4.38 q (2H,
2.30 s (3H, C6H4Me), 2.38 s (3H, Me), 4.29 q (2H,
3
3
OCH2, JHH = 7.0 Hz), 7.03–7.07 m and 7.15–7.55 m
OCH2, JHH = 7.1 Hz), 7.20–7.24 m and 7.34–7.42 m
(4H, C6H4), 13.39 s (1H, NH). 13C NMR spectrum
(4H, C6H4), 12.24 s (1H, NH); E isomer (62%): 1.33 t
3
[(CD3)2CO], δC, ppm (Z isomer, 100%): 55.92 (OMe),
(3H, CH2Me, JHH = 7.1 Hz), 2.31 s (3H, C6H4Me),
1
14.30 and 62.16 (OEt), 112.58 q (C4, JCF = 272.0,
3
2.50 s (3H, Me), 4.26 q (2H, OCH2, JHH = 7.1 Hz),
2JCF = 32.0 Hz), 106.58–120.18 (C5, C6, C7), 115.80,
(Co), 119.14 (Cm), 122.76 (Ci), 135.72 (C2), 159.65
(Cp), 176.16 t (C3, 2JCF = 22.7), 164.14. 19F NMR spec-
trum [(CD3)2CO], δF, ppm (Z isomer, 100%): 38.86 m
(2F, 6-F), 43.19 m (2F, 5-F), 52.69 m (2F, 4-F),
82.77 m (3F, CF3).
7.20–7.24 m and 7.34–7.42 m (4H, C6H4), 14.67 s (1H,
NH). 13C NMR spectrum [(CD3)2CO], δC, ppm: Z iso-
mer (38%): 20.91 (C6H4Me), 26.58 (C4), 14.63 and
61.09 (OEt), 116.19–140.41 (Carom), 136.13 (C2),
165.49 (C1), 193.51 (C3); E isomer (62%): 20.83
(C6H4Me), 30.67 (C4), 14.39 and 61.57 (OEt), 116.19–
140.41 (Carom), 136.13 (C2), 164.13 (C1), 197.12 (C3).
Found, %: C 62.97; H 6.47; N 11.02. C13H16N2O3. Cal-
culated, %: C 62.89; H 6.50; N 11.28.
Ethyl 4,4,5,5,6,6,7,7,7-nonafluoro-2-(4-methyl-
phenylhydrazono)-3-oxoheptanoate (Im). Yield
1
59%, orange powder, mp 44–45°C. NMR spectrum
(CDCl3), δ, ppm (Z isomer, 100%): 1.40 t (3H,
This study was performed under financial support
by the Council for Grants at the President of the Rus-
sian Federation (program for state support of leading
scientific schools, project no. 3758.2008.3).
3
CH2Me, JHH = 7.1 Hz), 2.35 s (3H, Me), 4.38 q (2H,
3
OCH2, JHH = 7.1 Hz), 7.14–7.17 m and 7.24–7.35 m
(4H, C6H4), 13.50 br.s (1H, NH). 19F NMR spectrum
(CDCl3), δF, ppm (Z isomer, 100%): 36.84 m (2F, 6-F),
41.26 m (2F, 5-F), 50.44 m (2F, 4-F), 81.10 m
(3F, CF3).
REFERENCES
Ethyl 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluoro-2-(4-
methylphenylhydrazono)-3-oxononanoic acid (In).
Yield 53%, yellow powder, mp 50–51°C. IR spectrum
(mineral oil), ν, cm–1: 3100 (NH); 1705, 1660 (C=O);
1. Kuzueva, O.G., Burgart, Ya.V., and Saloutin, V.I., Izv.
Ross. Akad. Nauk, Ser. Khim., 1998, p. 695; Burgart, Ya.V.,
Fokin, A.S., Kuzueva, O.G., Chupakhin, O.N., and Salou-
tin, V.I., J. Fluorine Chem., 1998, vol. 92, p. 101.
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STERIC STRUCTURE OF ALKYL 2-ARYL(HETARYL)HYDRAZONO-...
809
2. Khudina, O.G., Burgart, Ya.V., Saloutin, V.I., and Chu-
pakhin, O.N., J. Fluorine Chem., 2004, vol. 125, p. 401.
3. Khudina, O.G., Burgart, Ya.V., Murashova, N.V., and Sa-
loutin, V.I., Russ. J. Org. Chem., 2003, vol. 39, p. 1421.
4. Shchegol’kov, E.V., Burgart, Ya.V., and Saloutin, V.I.,
8. Khudina, O.G., Shchegol’kov, E.V., Burgart, Ya.V., Ko-
dess, M.I., Saloutin, V.I., Kazheva, O.N., Shilov, G.V.,
D’yachenko, O.A., Grishina, M.A., Potemkin, V.A., and
Chupakhin, O.N., Russ. J. Org. Chem., 2007, vol. 43,
p. 380.
9. Dewar, M.J.S., Zoebisch, E.G., Healy, E.F., and
Stewart, J.J.P., J. Am. Chem. Soc., 1985, vol. 107,
p. 3902.
J. Fluorine Chem., 2007, vol. 128, p. 779.
5. Khudina, O.G., Shchegol’kov, E.V., Burgart, Ya.V., and
Saloutin, V.I., Russ. J. Org. Chem., 2004, vol. 40, p. 813;
Khudina, O.G., Shchegol’kov, E.V., Burgart, Ya.V., Salo-
utin, V.I., and Chupakhin, O.N., J. Fluorine Chem., 2005,
vol. 125, p. 1363.
6. Shchegol’kov, E.V., Sadchikova, E.V., Burgart, Ya.V., and
Saloutin, V.I., Izv. Ross. Akad. Nauk, Ser. Khim., 2008,
p. 599.
10. Vereshchagin, A.N., Induktivnyi effekt. Konstanty za-
mestitelei dlya korrelyatsionnogo analiza (Inductive
Effect. Substituent Constants for Correlation Analysis),
Moscow: Nauka, 1988.
11. Scheldrick, G.M., SHELXS-97 and SHELXL-97, Göttin-
gen, Germany: Univ. of Göttingen, 1997.
12. Garg, H.G. and Singh, P.P., J. Med. Chem., 1968,
7. Mitchell, A. and Nonhebel, D.C., Tetrahedron, 1979,
vol. 35, p. 2013.
vol. 11, p. 1104.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 6 2009