Dimephosphone analogs: II. Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl) phosphine oxide oximes: Synthesis, structure, and generation of iminoxyl radicals

Article abstract of DOI:10.1134/S107036321405020X

Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine oxide oximes have been synthesized for the first time. According to the X-ray diffraction data, these compounds in crystal exist as a single E isomer. Their structure in solution and the E/Z isomer ratio were determined by ¹H and ¹³C NMR spectroscopy.

Full text of DOI:10.1134/S107036321405020X

ISSN 1070-3632, Russian Journal of General Chemistry, 2014, Vol. 84, No. 5, pp. 901–910. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © D.A. Tatarinov, V.F. Mironov, A.A. Kostin, E.V. Mironova, D.B. Krivolapov, V.I. Morozov, V.N. Nabiullin, A.V. Il’yasov, B.I. Buzykin,
2014, published in Zhurnal Obshchei Khimii, 2014, Vol. 84, No. 5, pp. 808–817.
Dimephosphone Analogs:
II.1 Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine
Oxide Oximes: Synthesis, Structure,
and Generation of Iminoxyl Radicals
D. A. Tatarinov, V. F. Mironov, A. A. Kostin, E. V. Mironova, D. B. Krivolapov,
V. I. Morozov, V. N. Nabiullin, A. V. Il’yasov, and B. I. Buzykin
Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences,
ul. Arbuzova 8, Kazan, 420088 Tatarstan, Russia
e-mail: datint@iopc.ru
Received August 5, 2013
Abstract—Dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine oxide oximes have been synthesized for the
first time. According to the X-ray diffraction data, these compounds in crystal exist as a single E isomer. Their
structure in solution and the E/Z isomer ratio were determined by 1H and 13C NMR spectroscopy.
DOI: 10.1134/S107036321405020X
The drug Dimephosphone [2-(dimethoxyphos-
phoryl)-2-methylpentan-4-one] is a γ-phosphorylated
ketone which attracts interest as precursor in the
synthesis of new potentially biologically active
compounds. Unlike most practically important
organophosphorus compounds, Dimephosphone is
low-toxic, it exhibits no anticholineesterase activity,
and was recommended as antidote; it also represents a
striking example of successful search for medicinal
agents among organophosphorus compounds [2, 3].
Dimephosphone is used as antiacidotic agent in the
treatment of acidoses of different origins and breathing
disorders and as vasoactive drug in the treatment of
cerebral circulation disorders. It displays membrane-
stabilizing and anti-inflammatory activity, improves
blood circulation, and normalizes cerebral metabolism.
In addition, Dimephosphone exhibits cardiotropic,
neurotropic, neuroprotective, antihypoxic, antiallergic,
immunomodulating, anti-aggregation, antioxidant,
radioprotective, and other useful properties [2, 3].
isonicotinoylhydrazones derived therefrom were found
to show antitubercular and anti-inflammatory activity,
being 13 times less toxic than Isoniazid [1, 5–7].
We previously developed a convenient procedure
for the synthesis of other Dimephosphone analogs,
dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine
oxides, where the two alkyl (aryl) radicals are directly
attached to the phosphorus atom [8–11]. The procedure
utilizes accessible derivatives of phosphorus-contain-
ing heterocycles with an endocyclic P–O bond and
Grignard reagents. For instance, 2-chloro-3,3,5-tri-
methyl-1,2λ5-oxaphosphole 2-oxide, which can be readily
prepared from simple and commercially accessible
phosphorus trichloride and mesityl oxide or diacetone
alcohol [12–15], is a convenient starting material for
the preparation of dialkyl(diaryl)-(2-methyl-4-oxopent-
2-yl)phosphine oxides (I). Such phosphine oxides
containing a carbonyl group in the γ-position with
respect to the phosphorus atom attract interest as
efficient fire retardants for poly(vinyl chloride) com-
positions [8] and as extractants for the isolation of
lanthanides from acid medium [16, 17]. Therefore, it
seemed reasonable to study some their chemical
properties in more detail.
Aza analogs of Dimephosphone, in which the
carbonyl group is replaced by a nitrogen containing
fragment, also exhibit biological activity [4–7]. For
example, Dimephosphone oxime possesses the same
properties as the parent ketone [4], and nicotinoyl- and
In this article we report on the synthesis of dialkyl-
1 For communication I, see [1].
(diaryl)(2-methyl-4-oxopent-2-yl)phosphine
oxide
901

902
TATARINOV et al.
Scheme 1.
O
P
O
P
R
R
R
R
NH2OH HCl
NaOH/EtOH
3
5
4
2
_NaCl, _H2O
1
6
N
O
HO
IIа_IIg
Iа_If
R = Et (а), Pr (b), Bu (c), C6H13 (d), СH2Ph (e), Ph (f), OMe (g).
oximes, their structure, and some chemical properties.
It is known that oximes, including phosphorylated
ones and Dimephosphone oxime, exhibit a broad
spectrum of biological activity and act as antidotes
toward organophosphorus chemical warfare agents [2,
4, 18–20]. Taking this into account, we have syn-
thesized oximes II by reaction of γ-phosphoryl ketones
I with hydroxylamine hydrochloride in ethanol at a
reactant ratio of 1 : 1.5 (Scheme 1).
equilibrium mixture of E and Z isomers. Afonin et al.
[23, 24] showed that the methyl carbon atom in the
trans position with respect to the lone electron pair on
the nitrogen atom resonates in a stronger field as
compared to the corresponding carbon atom in the cis.
In the 13C NMR spectrum of IIa, the major methyl
carbon signal (C5) appears as a quartet at δC 16.67 ppm
(1JHC = 127.6 Hz), which indicates E configuration of
the major isomer; the minor C5 signal belonging to the
Z isomer is located at δC 23.0 ppm (1JHC = 127.6 Hz).
The C3 signals in the proton-coupled 13C NMR
spectrum were triplets at δC 40.45 (major E isomer,
A small excess of NH2OH·HCl was necessary to
ensure complete conversion of ketones I into oximes
II, since under the action of sodium hydroxide
hydroxylamine free base was partly removed in the
gaseous state from the reaction mixture. The optimal
conditions included preliminary cooling of a mixture
of phosphine oxide and hydroxylamine hydrochloride
in ethanol using an ice bath and slow addition of
ethanolic sodium hydroxide under vigorous stirring.
All oximes IIa–IIg were isolated in quantitative yield.
1JHC = 128.2 Hz) and 33.18 ppm (minor Z isomer, 1JHC
=
128.8 Hz). In all cases, the C=N (C4) carbon signal of
the Z isomer was observed in a stronger field, and it
displayed coupling with the phosphorus nucleus with a
constant JCP of ~11.2–11.6 Hz; the corresponding
coupling constant for the E isomer was JCP = 13.2–
13.6 Hz. The 13C signal intensities provide only a
rough estimate of the isomer ratio.
The IR data showed that crystalline oximes IIa–IIf,
unlike Dimephosphone oxime (IIg) [21, 22], were
represented by a single isomer. However, the IR
spectra were insufficient to unambiguously determine
the isomer structure. By analogy with the data for
Dimephosphone aryl- and aroylhydrazones [1, 5–7]
and major isomer of Dimephosphone oxime [20, 21]
oximes IIa–IIg can be assigned E configuration. This
assumption was confirmed experimentally by analysis
1
For this purpose, we used the H NMR spectra. In
1
the H NMR spectrum of IIa, the major 3-H signal
(E isomer) appeared as a doublet in a stronger field, at
δ 2.25 ppm (3JPH = 7.7 Hz), and the 3-H proton of the
Z isomer resonated in a weaker field (δ 2.42 ppm, d,
3JPH = 7.9). The signal intensity ratio was 10:1. Some
parameters of the 13C and H NMR spectra of γ-
1
phosphoryl oximes are presented in Table 1.
1
of their H and 13C NMR spectra, as well as by the X-
ray diffraction data for dibutyl(2-methyl-4-oxopent-2-
yl)phosphine oxide oxime (IIc).
Figure 1 shows the molecular structure of oxime
IIc in crystal according to the X-ray diffraction data.
Oxime IIc has E configuration about the C=N bond.
The phosphorus atom is characterized by a distorted
tetrahedral configuration. The O1, P1, C2, C3, and C4
atoms lie almost in one plane (P1); the average
deviation of atoms from that plane is 0.038(3) Å. Plane
P1 is virtually almost orthogonal to the oxime fragment
C3C4C5N6O7 (P2), where the average deviation of
atoms from the mean-square plane is 0.017(3) Å. The
dihedral angle between P1 and P2 is 80.9(2)°. Unlike
Replacement of the carbonyl group in Ia–Ig by
hydroxyimino in going to oximes IIa–IIg did not
change the chemical shifts and multiplicities of signals
1
in the H and 13C NMR spectra to an appreciable
extent. The difference was that two sets of signals were
observed in the NMR spectra of oximes II due to the
1
presence of E and Z isomers. According to the H and
13C NMR data, oximes II in CDCl3 solution (cf. our
previous data for oximes IIa and IIe [11]) exist as
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DIMEPHOSPHONE ANALOGS: II.
903
Table 1. Some parameters of the 13C and 1H NMR spectra of the E and Z isomers of γ-phosphoryl oximes IIa–IIf
Chemical shifts, δ, δC, ppm
E/Z Isomer
ratio
Comp. no.
C3
H3
C4 δ ppm ( 3JPC, Hz)
152.35 (11.5)
152.77 (13.2)
152.95 (11.7)
154.46 (13.2)
154.11 (11.9)
154.38 (13.2)
153.44 (11.6)
153.81 (13.5)
152.45 (11.3)
152.74 (13.2)
151.99 (13.1)
152.31 (15.3)
C5
Z-IIa
E-IIa
Z-IIb
E-IIb
Z-IIc
E-IIc
Z-IId
E-IId
Z-IIe
E-IIe
Z-IIf
E-IIf
33.19
40.45
33.41
40.06
33.73
40.78
33.60
40.72
33.52
40.62
33.36
40.43
2.42
2.25
2.45
2.34
2.55
2.39
2.60
2.43
2.46
2.25
2.30
2.51
23.00
16.67
22.69
16.98
16.98
23.16
16.91
23.23
17.01
22.27
16.73
22.88
10 : 1
4 : 1
8 : 1
5 : 1
6 : 1
4 : 1
Dimephosphone 4-nitrophenylhydrazone [1], both P1
and P2 fragments in molecule IIc, as in Dime-
phosphone 2-nitrophenylhydrazone and aroylhyd-
razones [1] are turned apart with respect to the C3–C4
bond. Analogous molecular conformation is typical of
bis(2-methoxyphenyl)(2-methyl-4-oxopent-2-yl)phos-
phine oxide, where the torsion angle C2C3C4C5 is
–100.4(6)° [11].
Fig. 1. Structure of the molecule of dibutyl(4-hydroxyimino-2-methylpent-2-yl)phosphine oxide (IIc) according to the X-ray
diffraction data. Bond lengths, Å: P1–O1 1.494(2), P1–C2 1.845(3), P1–C10 1.802(3), P1–C14 1.802(3), O7–N6 1.401(4), O7–H7 0.93(5),
N6–C4 1.297(4). Bond angles, deg: O1P1C2 110.5(1), O1P1C10 112.1(1), C2P1C10 107.4(1), C2P1C14 110.5(1), C10P1C14 103.4(2),
N6O7H7 95(3), O7N6C4 110.2(3). Torsion angles, deg: O1P1C2C3 175.2(2), O1P1C2C9 51.6(2), O1P1C10C11 55.2(3), O1P1C14C15 62.3(3),
O7N6C4C5 3.6(4), O7N6C4C3 179.5(2), C2C3C4C5 84.8(4).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

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TATARINOV et al.
Fig. 2. Crystal packing of dibutyl(4-hydroxyimino-2-methylpent-2-yl)phosphine oxide (IIc).
Packing of molecules IIc in crystal is determined
more profound processes occurring in that solvent,
which led to nitroxyl radicals whose detailed structure
we failed to determine. Presumably, nitroxyl radicals
are formed as a result of various transformations of
initially formed iminoxyl radicals. It is well known
that most iminoxyl radicals (unlike nitroxyl radicals) in
solution readily undergo C–O, N–O, N–N, C–N, and
C–C dimerization, and the resulting dimers are capable
of reacting further [25–29]. In addition, intramolecular
hydrogen shifts from methyl or methylene groups
neighboring to the radical center are possible [28–30].
Therefore, we examined oxidation of oximes II with
PbO2 in methylene chloride and toluene, as well as
electrochemical oxidation in acetonitrile in the
presence of pyridine (MeCN–pyridine ratio 5.0 : 0.1;
Scheme 2).
by intermolecular hydrogen bonds between the
hydroxy proton and phosphoryl oxygen [O7–H7···O1,
O7–H7 0.93(5), H7···O1 1.79(5), O7···O1 2.670(3) Å,
∠O7H7O1 156(4)°, symmetry operation 1 + x, y, z].
These hydrogen bonds give rise to chains along the 0a
crystallographic axis (Fig. 2).
Oximes are precursors of iminoxyl radicals of the
general formula R1R2C=N–O·. Due to magnetic
properties of the phosphorus nucleus, iminoxyl
radicals having phosphorus-containing substituents
display high stereospecificity of the hyperfine coupling
constants (HCC), which allows reliable determination
of the ratio their Z and E isomers [25]. Iminoxyl
radicals containing various phosphorus substituents in
the α- and β-positions with respect to the radical center
have been studied in sufficient detail [25–27], whereas
the available data on their analogs with phosphorus
substituents in the γ-positions are fairly limited. Taking
into account that the stability and lifetime of iminoxyl
radicals strongly depend on the nature of substituents
in the alkylidene fragment, we tried to generate
iminoxyl radicals by oxidation of oximes II.
The solubility of oximes II in chloroform,
methylene chloride, and acetonitrile is higher than in
toluene. However, difficulties related to purification of
chlorine-containing solvents and fast formation therein
of impurities promoting side processes in the oxidation
of oximes reduce their value as medium for studying
such reactions. Toluene is the most appropriate solvent
for ESR studies, but the solubility of γ-phosphoryl
oximes IIa–IIf in that solvent is not always sufficient,
and only a small part of generated iminoxyl radicals
can be detected by ESR.
Like parent oximes, iminoxyl radicals in solution
may exist as two geometric isomers. The energy
barrier to Z/E isomerization of iminoxyls is lower than
that for the corresponding oximes; therefore, the
composition of the equilibrium mixture of Z and E
iminoxyl isomers always differs from the isomer
composition of the initial oxime [25].
Furthermore, iminoxyl radicals with a phosphoryl
fragment in the γ-position with respect to the radical
center are less stable than their α- and β-phosphoryl
analogs [25, 27]. In the oxidation of oxime IIg with
PbO2 or electrochemical oxidation, the formation of a
mixture of iminoxyl (IIIg) and nitroxyl radicals (g =
2.0054, aN = 9.5 Oe, aH = 10.67 Oe) was observed in a
Attempted generation of iminoxyl radicals via
oxidation of oximes II with lead(IV) oxide in
chloroform was unsuccessful. The results indicated
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DIMEPHOSPHONE ANALOGS: II.
905
Scheme 2.
H
O
N
R
P
R
P
R
R
H
N
O
O
O
Z-II
E-II
PbO2
R
O
N
R
R
R
N
P
P
O
O
O
E-III
Z-III
R = Et (а), Pr (b), Bu (c), C6H13 (d), Bn (e), Ph (f), OCH3 (g).
short time. Prolonged electrochemical oxidation in
MeCN in the presence of t-BuONa gave rise to two
nitroxyl radicals (g = 2.0054, aN = 14.61 Oe, aH =
20.03 Oe, aH = 1.22 Oe; g = 2.0054, aN = 13.76 Oe).
Presumably, initially formed unstable γ-phosphoryl
iminoxyl radicals III undergo various transformations.
pattern obtained in the oxidation of oxime IIe did not
allow us to reliably determine magnetic parameters.
The results of our experiments on the generation of γ-
phosphoryl iminoxyl radicals and their characteristics
are given in Table 2 and Figs. 3 and 4.
The small difference in the magnetic parameters of
iminoxyl radicals generated from oximes IIa, IIb, and
IIg (Table 2) may be rationalized by the rigidity of the
structural fragment linked to the phosphorus atom and
remoteness of varied substituents from the radical
center. Small differences in the electronic effects of the
methoxy groups in IIIg and alkyl groups in IIa, IIb
are leveled by the effect of the phosphoryl group.
According to the ESR data, γ-phosphoryl oximes
IIa–IIf, as well as Dimephosphone oxime (IIg), in the
examined solvents exist as two geometric isomers
whose ratio is determined mainly by the solvent nature
and, to a minor extent, by the nature of substituent in
the phosphoryl fragment. The E/Z isomer ratio for
radicals IIIa, IIIb, and IIIg was about 3 : 1). The ESR
Table 2. Parameters of the ESR spectra of the E and Z isomers of γ-phosphoryl iminoxyls IIIa, IIIb, and IIIg generated by
electrochemical oxidation of oximes IIa, IIb, and IIg in acetonitrile in the presence of pyridine (acetonitrile–pyridine ratio
5.0 : 0.1)a
Comp.
no.
Isomer
fraction, %
Isomer
Et
g-factorb
aN
a(CH3)
a(CH2)
aP
aP
IIIа
IIIb
IIIg
E
Z
E
Z
E
Z
57 (~75) 2.0057 (2.0057) 30.626 (30.578) 1.655 (1.544) 1.469 (1.417) 0.908 (0.792)
43 (~25) 2.0058 (2.0058) 30.756 (30.513) 1.459 (1.482) 1.267 (1.055) 0.25c (>0.28c)
51 (~75) 2.0057 (2.0057) 30.678 (30.576) 1.674 (1.545) 1.450 (1.419) 0.901 (0.793)
49 (~25) 2.0058 (2.0058) 30.756 (30.515) 1.490 (1.480) 1.152 (1.057) 0.25c (>0.28c)
64 (~75) 2.0057 (2.0057) 30.634 (30.577) 1.711 (1.545) 1.440 (1.418) 0.937 (0.800)
36 (~25) 2.0058 (2.0058) 30.813 (30.514) 1.591 (1.481) 1.099 (1.056) 0.25c (>0.28c)
Pr
MeO
a
Parameters of the ESR spectra of iminoxyls IIIa, IIIb, and IIIg generated by oxidation of oximes IIa, IIb, and IIg with PbO2 in toluene
are given in parentheses. Difference in the fifth decimal point. Maximum possible value of the hyperfine coupling constant with the
phosphorus nucleus, which is masked by the line width.
b
c
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

906
TATARINOV et al.
Н, Oe
Fig. 4. (1) Experimental ESR spectrum of a mixture of
radicals generated by electrochemical oxidation of
Dimephosphone oxime (IIg) in acetonitrile in the presence
of pyridine (acetonitrile–pyridine ratio 5.0 : 0.1), (2)
theoretical ESR spectrum of iminoxyl radical IIIa, and (3)
experimental ESR spectrum of nitroxyl radical generated
from IIIa.
Н, Oe
Fig. 3. (1) Experimental and (2) theoretical ESR spectra of
iminoxyl radical IIIa generated by oxidation of oxime IIa
with lead dioxide in toluene.
Hyperfine coupling with a phosphorus nucleus in
the γ-position (so-called W-coupling) to the radical
center in iminoxyl radicals has been reported [25, 27].
However, we observed almost no effect of the
phosphorus atom in the ESR spectra of iminoxyl
radicals generated by oxidation of oximes IIa, IIb, and
IIg. A probable reason is their rigid structure due to the
presence of two methyl groups in the α-position with
respect to the phosphorus atom.
monochromator; λMoKα radiation, λ 0.71073 Å; ω-
scanning). A correction for absorption was applied
semiempirically using SADABS program [31]. The
structure was solved by the direct method using SIR
program [32] and was refined in isotropic and
anisotropic approximations with the aid of SHELXL–
97 software package [33]. The position of the H7 atom
was determined from the difference Fourier maps and
was refined in isotropic approximation. The other
hydrogen atoms were placed into geometrically
calculated positions and were included in the
refinement procedure according to the riding model.
All calculations were performed using WinGX [34]
and APEX2 [35]. The molecular structure was plotted,
and intermolecular interactions were analyzed, using
PLATON [36] and ORTEP [37].
EXPERIMENTAL
The 1H, 31P, and 13C NMR spectra were recorded on
a Bruker Avance-400 spectrometer at 400, 160.9, and
100.6 MHz, respectively. The IR spectra were
measured on a Bruker Vector-22 instrument from
samples dispersed in mineral oil or pelletized with
KBr. The melting points were determined on a Boetius
melting point apparatus. The mass spectra (electron
impact) were obtained on a Finnigan Trace MS GC/MS
system; samples were injected as solutions in ethanol.
The ESR spectra were recorded at room temperature
on a Radiopan SE/X 2544 spectrometer equipped with
an RCX 660 dielectric resonator (variable operating
frequency, 9.1–9.8 GHz, klystron source, maximum
output power 100 mW) at a constant microwave
radiation frequency with variation of the magnetic
field using external magnetic field modulation.
Colorless prisms, monoclinic crystal system;
C14H30NO2P; M 275.36; unit cell parameters: a =
9.1697(17), b = 20.772(4), c = 9.3557(18) Å; β =
109.636(2)°; V = 1678.4(5) Å3; dcalc = 1.090 g/cm3; Z =
4; space group P21/n; scan range 1.96° < θ < 26.00°;
μ(MoKα) = 1.61 cm–1. Total of 3106 independent
reflection intensities were measured, 2423 of which
were characterized by I ≥ 2σ(I). Final divergence
factors: R = 0.0617, Rw = 0.1442 for 2423 reflections
with F > 2σ(F2).
Generation of iminoxyl radicals. A solution of
oxime IIa, IIb, or IId–IIg in chloroform, methylene
chloride, toluene, or acetonitrile with a concentration
approaching saturation was placed into a 4-mm
The X-ray diffraction data for a single crystal of
oxime IIc were obtained at 293 K on a Bruker Smart
APEX II CCD automatic diffractometer (graphite
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DIMEPHOSPHONE ANALOGS: II.
907
(external diameter) ampule, and a required amount of
lead dioxide was added. The ampule was shaken,
cooled with liquid nitrogen, evacuated using a
forevacuum pump, and defrosted. This procedure was
repeated in triplicate to ensure complete deoxygena-
tion, and the ampule was sealed. When chloroform was
used as solvent (oxime concentration 1 mM), after
addition of PbO2, the mixture was purged with argon
over a period of 10 min, and the ampule was sealed.
Diethyl(4-hydroxyimino-2-methylpent-2-yl)-
phosphine oxide (IIa). Yield 82%, mp 98°C; Z/E ratio
1 : 10. IR spectrum, ν, cm–1: 468, 529, 603, 659, 709,
762, 789, 840, 883, 948, 972, 1023, 1135, 1168, 1240,
1276, 1324, 1370, 1390, 1411, 1466, 1648, 2164,
2883, 2943, 2972, 3068, 3200, 3385. 1H NMR
spectrum (CDCl3), δ, ppm (J, Hz): 1.01 d (6H, 1-H,
3
3
6-H, E, JPH = 14.2), 1.05 d (6H, 1-H, 6-H, Z, JPH
=
3
14.1), 1.05 br.t (6H, 8-H, JHH = 15.2), 1.45–1.72 m
(4H, 7-H, AB part of ABMX3 spin system), 1.73 br.s
(3H, 5-H, E), 1.74 br.s (3H, 5-H, Z), 2.25 d (2H, 3-H,
The ampule containing the reaction mixture was
then placed into a 5-mm ER4118MD5-W1 dielectric
cylindrical resonator, and samples were irradiated at a
power of 2 mW; static magnetic field was modulated
by alternating magnetic field with a frequency of
100 kHz and an amplitude of 1 G.
3
3
E, JPH = 7.7), 2.42 d (2H, 3-H, Z, JPH = 7.9), 10.79 s
(1H, OH). 13C–{1H} NMR spectrum (CDCl3), δC, ppm
(J, Hz) (hereinafter, the multiplicity of signals in the
proton-coupled spectrum is given parentheses): 6.14
1
2
2
q.d. t (d) (C8, E, JHC = 128.7, JPC = 5.4, JHC ≈ 5.4),
6.16 br.q (d) (C8, Z, JHC ≈ 128.7, JPC = 5.3, JHC
≈
1
2
2
ESR studies in combination with electrolysis in situ
were carried out using a setup consisting of a Radiopan
SE/X-2544 radiospectrometer, a potentiostat, and a
custom-made electrochemical cell. This setup allowed
the electrolysis to be performed directly in the ESR
probe. A platinum plate was used as working electrode,
platinum wire was used as auxiliary electrode, and
silver wire was a reference electrode. Solutions were
deaerated by three freeze–evacuation–thaw cycles. The
electrolysis was carried out in acetonitrile at 293–333 K
with 0.1 M Et4NClO4 as supporting electrolyte.
Organic solvents were dried and purified according to
standard procedures. Tetrabutylammonium tetrafluoro-
borate and sodium tert-butoxide were used without
additional purification.
5.4), 16.31 br.d.t (d) (C7, Z, 1JHC ≈ 126.1, 1JPC = 62.0),
16.41 br.d.t (d) (C7, Z, 1JHC = 126.1, 1JPC = 62.0), 16.67
br.q (s) (C5, E, 1JHC = 127.6), 21.09 q.m (s) (C1, C6, E,
1JHC = 127.8), 21.94 q.m (s) (C1, C6, Z, JHC = 127.9),
1
23.00 br.q (s) (C5, Z, JHC = 127.6), 33.19 br.t (s) (C3,
1
Z, 1JHC = 128.8), 35.75 br.d (d) (C2, 1JPC = 64.2), 40.45
br.t (s) (C3, E, JHC = 128.2), 152.35 m (d) (C4, Z,
1
3JPC = 11.5 ), 152.77 m (d) (C4, E, JPC = 13.2 ). 31P–
3
{1H} NMR spectrum (CDCl3), δP, ppm: 58.1 (E), 58.8
(Z). Found, %: C 54.63; H 10.47; N 6.34; P 13.95.
C10H22NO2P. Calculated, %: C 54.78; H 10.11; N 6.39;
P 14.13.
(4-Hydroxyimino-2-methylpent-2-yl)dipropyl-
phosphine oxide (IIb). Yield 95%, mp 105°C, Z/E
ratio 1 : 4. IR spectrum, ν, cm–1: 468, 523, 549, 602,
624, 714, 738, 762, 788, 844, 882, 904, 951, 975,
1027, 1135, 1165, 1239, 1321, 1370, 1388, 1408,
Dimethyl (4-hydroxyimino-2-methylpent-2-yl)phos-
phonate (IIg) was synthesized according to the proce-
dure described in [21].
1
General procedure for the synthesis of oximes
IIa–IIf. A mixture of 0.0245 mol of phosphine oxide
Ia–If and 3.8 g (0.0539 mol) of hydroxylamine
hydrochloride in 10 mL of ethanol was cooled in an ice
bath, and a solution of 2.2 g (0.0539 mol) of sodium
hydroxide in 10 mL of ethanol was added dropwise
under stirring. When the reaction was complete, the
mixture was heated to the boiling point and cooled to
room temperature, the solvent was removed, and the
residue was dried at 60°C under reduced pressure
(10 mm). The residue was dissolved in methylene
chloride, the undissolved material was filtered off, the
solvent was removed from the filtrate under reduced
pressure (60°C, 10 mm), and the oily residue crystal-
lized on storage. After washing with diethyl ether, a
white crystalline substance was obtained.
1463, 1649, 2871, 2930, 2964, 3057, 3156. H NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.85 t (6H, 9-H,
3JHH = 7.0), 0.86 t (6H, 9-H, 3JHH = 7.2), 1.02 d (6H, 1-
H, 6-H, E, 3JPH = 14.6), 1.05 d (6H, 1-H, 6-H, Z, 3JPH
=
14.9), 1.38–1.73 m (8H, 7-H, 8-H), 1.79 br.s (3H, 5-H,
E) 1.81 s (3H, 5-H, Z), 2.34 d (2H, 3-H, E, 3JPH = 7.9),
3
2.45 d (2H, 3-H, Z, JPH = 8.1), 11.38 br.s (1H, OH).
13C NMR spectrum (CDCl3), δC, ppm (J, Hz): 15.60
t.d.m (d) (C8, 1JHC = 128.3, 2JPC = 4.4), 15.79 q.d.m (d)
(C9, E, 1JHC = 125.0, 3JPC = 14.2), 15.82 q.d.m (d) (C9,
1
3
Z, JHC = 125.7, JPC = 14.1), 16.98 br.q (s) (C5, E,
1JHC ≈ 129.0), 21.01 q.m (s) (C1, C6, E, JHC = 128.0),
1
21.82 q.m (s) (C1, C6, Z, JHC = 128.0), 22.69 br.q (s)
1
(C5, Z, JHC = 128.2), 25.98 br.d.t (d) (C7, Z, JHC
≈
=
1
1
127.7, JPC = 60.8), 26.09 br.d.t (d) (C7, Z, JHC
1
1
126.6, 1JPC = 60.8), 33.41 br.t (s) (C3, Z, 1JHC = 129.3),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

908
TATARINOV et al.
1
1
35.72 br.d (d) (C2, JPC = 64.0), 40.06 br.t (s) (C3, E,
(br.s) (C1, C6, JHC = 127.7), 22.23 t.m (d) (C8, E,
1JHC = 129.4), 153.95 m (d) (C4, Z, 3JPC = 11.7), 154.46
1JHC ≈ 127.4, JPC = 4.5), 22.25 t.m (d) (C8, Z, JHC
≈
2
1
m (d) (C4, E, JPC = 13.2). 31P–{1H} NMR spectrum
127.4, JPC = 4.4), 22.44 t.m (s) (C11, JHC = 125.1),
3
2
1
(CDCl3), δP, ppm: 59.1 (E), 59.8 (Z). Found, %: C
58.25; H 11.54; N 5.68; P 11.55. C12H26NO2P.
Calculated, %: C 58.28; H 10.60; N 5.66; P 11.52.
23.23 q.m (s) (C5, Z, 1JHC = 127.5), 24.44 br.d.t (d) (C7,
E, JHC ≈ 126.0, JPC = 60.9), 24.52 br.d.t (d) (C7, E,
1
1
1JHC = 126.3, JPC = 60.9), 31.20 t.d.m (d) (C9, JHC
≈
1
1
126.1, 3JPC = 12.9), 31.33 br.t.m (s) (C10, 1JHC ≈ 125.6),
Dibutyl(4-hydroxyimino-2-methylpent-2-yl)-
phosphine oxide (IIc). Yield 75%, mp 97°C, Z/E ratio
1 : 8. IR spectrum, ν, cm–1: 439, 471, 497, 529, 584,
623, 684, 719, 742, 753, 795, 842, 875, 901, 952, 972,
997, 1019, 1050, 1063, 1112, 1123, 1164, 1193, 1210,
1222, 1235, 1285, 1303, 1329, 1377, 1419, 1464,
33.60 br.t (s) (C3, Z, JHC = 125.5), 36.09 br.d (d) (C2,
1
1JPC = 64.1), 40.72 br.t (s) (C3, E, 1JHC = 128.9), 153.44
m (d) (C4, Z, JPC = 11.6), 153.81 m (d) (C4, E, JPC
=
3
3
13.5). 31P–{1H} NMR spectrum (CDCl3), δP, ppm 56.6
(E), 56.8 (Z). Found, %: C 65.17; H 11.77; N 4.39; P
9.44. C18H38NO2P. Calculated, %: C 65.26; H 11.48; N
4.23; P 9.37.
1
1641, 2856, 2922, 3139. H NMR spectrum (CDCl3),
δ, ppm (J, Hz): 0.87 t (6H, 10-H, JHH = 7.3), 1.12 d
3
3
(6H, 1-H, 6-H, E, JPH = 14.5), 1.17 d (6H, 1-H, 6-H,
Dibenzyl(4-hydroxyimino-2-methylpent-2-yl)-
phosphine oxide (IIe). Yield 77%, mp 145–147°C,
Z/E ratio 1 : 6. IR spectrum, ν, cm–1: 698, 834, 969,
1000, 1113, 1124, 1170, 1239, 1377, 1394, 1408,
1463, 1496, 1580, 2669, 2855, 2924, 3147. H NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.98 d (6H, 1-H,
6-H, E, JPH = 14.9), 1.01 d (6H, 1-H, 6-H, Z, JPH
14.9), 1.70 s (3H, 5-H, E), 1.75 s (3H, 5-H, Z), 2.25 d
(2H, 3-H, E, JPH = 8.3), 2.46 d (2H, 3-H, Z, JPH =
Z, 3JPH = 14.6), 1.35 m (4H, 8-H), 1.45–1.67 m (4H, 9-H),
1.74 m (4H, 7-H, AB part of ABMX3), 1.88 s (3H, 5-H)
3
2.39 d (2H, 3-H, E, JPH = 7.4) 2.55 d (2H, 3-H, Z,
3JPH = 7.7). 13C NMR spectrum (CDCl3, 32°C), δC,
1
ppm (J, Hz): 13.65 q.t.t (s) (C10, JHC = 124.9, JHC
=
1
3
3.3–4.4), 16.98 br.q (s) (C5, E, JHC = 125.0), 21.46
=
1
3
3
q.m (br.s) (C1, C6, 1JHC = 127.8, 3JPC = 4.5), 23.16 br.q
(s) (C5, Z, 1JHC ≈ 125.0), 24.18 br.d.t (d) (C7, Z, 1JHC
=
=
3
3
123.6, JPC = 62.1), 24.28 br.d.t (d) (C7, E, JHC
8.3), 3.02 m (2H, 7-H, A part of ABX, JAB = 14.8,
1
1
2
123.6, JPC = 61.1), 24.34 t.d.m (d) (C8, JHC = 124.9,
2JAX = 11.9 Hz), 3.28 m (2H, 7-H, B part of ABX,
1
1
2JPC = 4.4), 24.61 t.d.m (d) (C9, JHC = 129.5, JPC
=
2JBA = 14.8, JBX = 11.9 Hz), 7.15–7.25 m (10H, 9-H,
1
3
2
13.2), 33.73 t (s) (C3, Z, 1JHC = 128.1), 36.17 d (d), (C2,
1JPC = 64.4), 40.78 t (s) (C3, E, 1JHC = 128.1), 154.11 m
10-H, 11-H), 10.59 s (1H, OH). 13C NMR spectrum
(DMSO-d6), δC, ppm (J, Hz): 17.01 br.q (s) (C5, E,
(d) (C4, Z, JPC = 11.9), 154.38 m (d) (C4, E, JPC
=
1JHC = 128.1), 21.61 q.m (s) (C1, C6, E, JHC = 127.9),
3
3
1
13.2). 31P–{1H} NMR spectrum (CDCl3), δP, ppm:
58.4 (E), 59.4 (Z). Found, %: C 61.33; H 11.17; N
5.12; P 11.41. C14H30NO2P. Calculated, %: C 61.09; H
10.90; N 5.09; P 11.27.
22.27 br.q (s) (C5, Z, JHC = 127.9), 22.46 q.m (s) (C1,
1
C6, Z, JHC = 128.0), 31.38 t.d (d) (C7, Z, JPC = 56.2,
1
1
1JHC = 125.0), 31.65 t.d (d) (C7, E, JPC = 56.3, JHC
=
1
1
128.2), 33.52 br.t (s) (C3, Z, JHC = 125.0), 36.81 br.d
1
(d) (C2, JPC = 64.2), 40.62 br.t (s) (C3, E, JHC
=
1
1
Dihexyl(4-hydroxyimino-2-methylpent-2-yl)-
phosphine oxide (IId). Yield 89%, yellow–brown
crystals, mp 66–67°C, Z/E ratio 1 : 5. IR spectrum, ν,
cm–1: 472, 532, 601, 634, 669, 717, 791, 840, 884, 950,
973, 1003, 1023, 1137, 1168, 1208, 1240, 1261, 1296,
1321, 1369, 1388, 1411, 1467, 1541, 1647, 2341,
2360, 2871, 2929, 2958, 3062, 3177. 1H NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.88 t (6H, 12-H,
3JHH = 6.9), 1.17 d (6H, 1-H, 6-H, E, 3JPH = 14.7), 1.25
125.6), 152.45 m (d) (C4, Z, 3JRC = 11.3 ), 152.74 m (d)
(C4, E, JPC = 13.2 ), 133.14 m (d) (C8, JPC = 7.8),
3
2
130.28 d.m (d) (C9, JHC = 160.3, JPC = 4.9), 128.37
1
3
d.m (d) (C10, Z, JHC = 160.2, JHC = 4.3, JPC = 1.7),
1
3
4
128.42 d.m (d) (C10, Z, JHC = 160.9, JPC = 1.7),
126.54 d.m (d) (C11, 1JHC = 160.8, 5JPC = 2.1). 31P–{1H}
NMR spectrum (CDCl3), δP, ppm: 50.2 (E), 50.8 (Z).
Found, %: C 70.11; H 7.85; N 4.12; P 8.78. C20H26NO2P.
Calculated, %: C 69.97; H 7.58; N 4.08; P 9.04.
1
4
3
d (6H, 1-H, 6-H, Z, JPH = 15.6), 1.27 m (8H, 10-H,
11-H), 1.38 m (4H, 7-H), 1.51–1.83 m (8H, 8-H, 9-H),
(4-Hydroxyimino-2-methylpent-2-yl)diphenyl-
phosphine oxide (IIf). Yield 98%, mp 207–208°C;
published data [38]: mp 214–216°C; Z/E ratio 1 : 4. IR
spectrum, ν, cm–1: 420, 511, 541, 582, 715, 753, 780,
937, 996, 1022, 1075, 1093, 1109, 1139, 1174, 1339,
1360, 1383, 1416, 1436, 1468, 1723, 2887, 2919,
1.92 s (3H, 5-H, E), 1.93 s (3H, 5-H, Z), 2.43 d (2H,
3
3
3-H, E, JPH = 7.5), 2.60 d (2H, 3-H, Z, JPH = 7.8),
9.13 br.s (1H, OH). 13C NMR spectrum (CDCl3, 32°C),
δC, ppm (J, Hz): 13.96 br.q.t (s) (C12, E, JHC = 124.5,
1
3JHC = 3.7), 15.19 br.q.t (s) (C12, Z, 1JNC ≈ 125.9, 3JHC
=
4.0), 16.91 q.t (s) (C5, E, JHC = 128.8), 21.34 q.m
2970, 2990, 3055, 3412. H NMR spectrum (CDCl3),
1
1
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 5 2014

DIMEPHOSPHONE ANALOGS: II.
909
3
Kostin “Socium, Health, Medicine), Saransk, 2005,
p. 37.
5. Buzykin, B.I., Nabiullin, V.N., Mironov, V.F., Chest-
nova, R.V., Garaev, R.S., Kashapov, L.R., Mironova, E.V.,
Tatarinov, D.A., and Kostin, A.A., RF Patent
no. 2471787, 2012; Byull. Izobret., 2012, no. 21.
6. Buzykin, B.I., Nabiullin, V.N., Mironov, V.F., Chest-
nova, R.V., Garaev, R.S., Kashapov, L.R., Mironova, E.V.,
Tatarinov, D.A., and Kostin, A.A., RF Patent
no. 2471787, 2013; Byull. Izobret., 2013, no. 1.
7. Buzykin, B.I., Nabiullin, V.N., Garaev, R.S., Chestno-
va, R.V., Kashapov, L.R., Valiev, R.Sh., and Mironov, V.F.,
Pharm Chem. J., 2013, vol. 46, no. 1, p. 35.
8. Mironov, V.F., Tatarinov, D.A., Baronova, T.A.,
Konovalov, A.I., Kostin, A.A., and Kryshtob, V.I., RF
Patent no, 2374260, 2009; Byull. Izobret., 2009, no. 23.
9. Tatarinov, D.A., Mironov, V.F., Kostin, A.A., Barono-
va, T.A., and Buzykin, B.I., Russ. J. Gen. Chem., 2010,
vol. 80, no. 7, p. 1377.
10. Tatarinov, D.A., Mironov, V.F., Baronova, T.A., Kos-
tin, A.A., Krivolapov, D.B., Buzykin, B.I., and Litvi-
nov, I.A., Mendeleev Commun., 2010, vol. 20, no. 2,
p. 86.
δ, ppm (J, Hz): 1.10 d (6H, 1-H, 6-H, E, JHH = 15.8),
1.13 d (6H, 1-H, 6-H, Z, 3JHH = 15.8), 1.68 s (3H, 5-H,
E), 1.74 s (3H, 5-H, Z), 2.30 d (2H, 3-H, JPH = 7.5),
3
3
2.51 d (2H, 3-H, JPH = 8.3), 7.50–7.64 m (7H, 8-H,
9-H, 10-H, OH), 7.96 m (4H, 7-H). 13C NMR spectrum
(CDCl33), δC, ppm (J, Hz): 16.73 q.t (s) (C5, E, JHC
=
=
1
127.0, JHC = 3.0), 21.62 q.m (s) (C1, C6, E, JHC
1
127.9), 22.57 q.m (s) (C1, C6, Z, JHC = 128.1), 22.88
1
br.q (s) (C5, Z, JHC ≈ 125.6), 33.36 br.t (s) (C3, Z,
1
1JHC = 126.4), 36.72 br.d (d) (C2, E, 1JPC = 69.4), 36.99
br.d (d) (C2, E, 1JPC = 69.2), 40.43 br.t (s) (C3, E, 1JHC
=
125.0), 128.72 d.d.d (d) (C9, JHC = 162.3, JHC = 7.0,
1
3
3JPC = 10.7), 130.47 d.m (d) (C7, E, 1JPC = 89.6, 3JHC
=
7.0), 130.67 d.m (d) (C7, Z, JPC = 89.4), 132.00 d.m
2
(d) (C10, JHC = 161.5, JHC = 6.7, JPC = 2.5), 132.22
1
3
4
1
3
2
d.m (d) (C8, JHC = 161.2, JHC = 6.2, JPC = 8.0),
151.99 m (d) (C4, Z, 3JPC = 13.1 ), 152.31 m (d) (C4, E,
3JPC = 15.3 ). 31P–{1H} NMR spectrum (CDCl3), δP,
ppm 61.5 (E), 64.6 (Z). Found, %: C 68.63; H 7.13; N
4.51; P 9.71. C18H22NO2P. Calculated, %: C 68.57; H
6.98; N 4.44; P 9.84.
11. Tatarinov, D.A., Kostin, A.A., Baronova, T.A.,
Dobrynin, A.B., Mironova, E.V., Krivolapov, D.B.,
Buzykin, B.I., and Mironov, V.F., Russ. J. Org. Chem.,
2013, vol. 49, no. 4, p. 516.
12. Nurtdinov, S.Kh., Khairullin, R.S., Tsivunin, V.S.,
Zykova, T.V., and Kamai, G.Kh., Zh. Obshch. Khim.,
1970, vol. 40, no. 11, p. 2377.
ACKNOWLEDGMENTS
This study was performed under financial support
by the Russian Foundation for Basic Research and by
the Academy of Sciences of Tatarstan Republic
(project no. 12-03-97042r_povolzh’e_a).
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1967, p. 248.
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16. Elistratova, Yu.G., Mustafina, A.R., Tatarinov, D.A.,
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