Direct C-C coupling of cyclic aldonitrones with 1,2,4-triazines using SNH reactions

Article abstract of DOI:10.1007/s10593-012-1124-x

New nitrogen heterocyclic derivatives were obtained by a direct uncatalyzed by metals C-C cross-coupling of a cyclic aldonitrone lithium derivative with 1,2,4-triazines.

Full text of DOI:10.1007/s10593-012-1124-x

Chemistry of Heterocyclic Compounds, Vol. 48, No. 8, November, 2012 (Russian Original Vol. 48, No. 8, August, 2012)
DIRECT C–C COUPLING OF CYCLIC ALDONITRONES
WITH 1,2,4-TRIAZINES USING SNH REACTIONS
M. V. Varaksin,1,2 I. A. Utepova,2 and O. N. Chupakhin1,2*
New nitrogen heterocyclic derivatives were obtained by a direct uncatalyzed by metals C–C cross-
coupling of a cyclic aldonitrone lithium derivative with 1,2,4-triazines.
Keywords: aldonitrones, 1,2,4-triazines, SNH reactions.
The development of efficient methods for the construction of new C–C bonds in aromatic and
heteroaromatic compounds is a very important strategic problem in synthetic organic chemistry. Such methods
are the Suzuki, Negishi, Stille, Kumada, Hiyama and other cross-coupling reactions catalyzed by transition
metals, such as Pd, Ni, Cu etc. [1, 2]. As a rule, these are reactions of organoelement compounds (boron, zinc,
tin, silicon, and magnesium derivatives) with halides or triflates. Although this approach is commonly employed
in the creation of C(sp3,sp2,sp)–C(sp3,sp2) bonds, it has several limitations arising from the need for prior
introduction of auxiliary groups into the reagent structure and the use of metal complex catalysts.
An alternative method for the formation of C(sp2)–C(sp3,sp2) bonds is the direct C–H functionalization of
H
arenes and hetarenes [3]. A variation of this method is the nucleophilic aromatic substitution of hydrogen (SN
reactions) [4, 5], which may be seen as an atom-economical and "green" synthetic approach. The economical
advantage of this strategy lies in minimization of the number of auxiliary steps and additional reagents, especially,
H
expensive noble metal catalysts. The "green" advantage arises since SN reactions, as a rule, proceed under mild
conditions, and the side products are usually environmentally harmless compounds, most often water.
In the present work, we present a simple and convenient method for the preparation of functionally-
substituted azaheterocycles, based on SNH reactions of a aldonitrone lithium derivative with 1,2,4-triazines. The
synthesis of such compounds is of interest since promising materials containing nitrones [6-8] and triazines
[9-11] have been reported.
Ph
H
Ph
N
N
s-BuLi, THF
+
N
+
N
–70°C
Li
O
O
2
1
_______
*To whom correspondence should be addressed, e-mail: chupakhin@ios.uran.ru.
1Ural Federal University named after the First President of Russia B. N. Yel'tsin, 19 Mira St., Yekaterinburg
620002, Russia; i.a.utepova@ustu.ru.
2I. Ya. Postovskii Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, 22
S. Kovalevskoi St., Yekaterinburg 620041, Russia.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1301-1308, August, 2012.
Original article submitted February 9, 2012.
0009-3122/12/4808-1213©2012 Springer Science+Business Media New York
1213

It is known that nitrones 1, which contain a hydrogen atom at the α-carbon atom relative to the N-oxide
group, display acidic properties and form the corresponding lithium derivatives 2 upon reaction with
organometallic bases such as s-BuLi and lithium diisopropylamide (LDA) [12]. The relative stability of the
intermediates, which are dipole-stabilized carbanions [13], is attributed to a thermodynamically-advantageous
intramolecular coordination bond.
The cyclic aldonitrone lithium derivative 2 reacts with 3,6-diphenyl-1,2,4-triazine N-oxide (3). The
selection of bicyclic nitrone 2 as the nucleophilic synthon and 3,6-disubstituted 1,2,4-triazines as the
electrophilic components was made in light of the synthetic availability of these reagents. This reaction most
likely proceeds through the formation of an unstable σH-adduct 4-OLi, which is the product of the addition of
lithium derivative 2 to the triazine N-oxide 3 [14]. Intermediate 4-OLi converts into 4-OH by the action of an
equimolar amount of water. The aromatization of intermediate 4-OH may be carried out by either elimination
H
H
(SN (AE)) or oxidation (SN (AO)). The dihydro derivative 4-OH gives triazine 5 in 82% yield as the result of
loss of a water molecule. The use of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as the oxidizing agent leads
to triazine N-oxide 6 in 65% yield. DDQ was selected since this reagent has already proved effective in other
H
SN (AO) reactions [15, 16].
Ph
H
N
N
N
Ph
N
Ph
N
H2O
Ph
N
THF
N+
2
+
OLi
–70°C
N+
Ph
–LiOH
O
O
3
4-OLi
Ph
N
N
N
Ph
Ph
N
N+
O
SNH (AE)
Ph
H
N
N
–H2O
82%
N
Ph
5
Ph
N
N+
OH
Ph
N
DDQ
65%
O
N
Ph
N
N+
O
Ph
4-OH
SNH (AO)
N+
O
6
The structures of the resultant heterocycles 5 and 6 were supported by elemental analysis, mass
1
13
1
spectrometry, and IR, H NMR, and C NMR spectroscopy data. The H NMR spectra show signals for the
protons of the spirofused cyclohexyl fragment as broad multiplets (1.17-2.01 ppm) and of the phenyl
substituents at 7.29-8.32 ppm. The 13C NMR spectra show characteristic resonance signals for the carbon nuclei
[17]. The mass spectra display characteristic peaks of m/z 460 and 476, corresponding to the [M+H]+ molecular
ions of products 5 and 6.
X-ray structural analysis was carried out to confirm the position of the N-oxide fragment in triazine 5
(Fig. 1). The analysis showed that the triazine 5 forms orthorhombic crystals with space group Pna21. No
significant deviations of the bond lengths and angles from standard values [18] were found. The triazine and
imidazole rings are planar, and the deviations of the atoms from the mean planes in both cases are not more than
1214

0.008 Å. The dihedral angle between the planes of the five- and six-membered azaheterocycles is 64.58°.
In our study of this SNH reaction, we discovered that the dipole-stabilized carbanion 2 reacts smoothly not
only with the highly electrophilic triazine N-oxide 3, but also with less reactive species, namely, unactivated
H
1,2,4-triazines 7a-d. This transformation should also be seen as a two-step SN reaction leading to previously
unreported triazinyl-containing 2H-imidazole derivatives. The first step most likely also involves nucleophilic
addition of lithium derivative 2 to the HC=N bond of azine 7a-d to give σH-adducts (8a-d)-NLi. These
intermediates have limited stability and are converted irreversibly in the presence of water into dihydro
derivatives (8a-d)-NH, which are capable of existing in two tautomeric forms: A-(8a-d)-NH and B-(8a-d)-NH.
The second step features loss of a water molecule to form heterocyclic derivatives 9a-d without an N-oxide
function in the structure. The yield of reaction products 9a-d is 75-85%. We should note that the loss of a water
H
molecule from the imidazole fragment permits classification of this SN reaction as a vicarious nucleophilic
substitution of hydrogen [19, 20].
Fig. 1. Molecular structure of triazine 5. The hydrogen atoms are represented by thermal vibration ellipsoids of
50% probability.
R1
N
N
Ph
R1
H
N
N
R2
N
H2O
THF
N
+
2
N+
–70°C
–LiOH
Li
N
R2
O
7a–d
(8a–d)-NLi
R1
N
R1
R1
H
N
N
N
N
N
N
N
Ph
N
Ph
N
Ph
N
R2
R2
N
R2
–H2O
N
H
N+
75–85%
H
N
O
SNH (AE)
OH
A-(8a–d)-NH
a R1 = R2 = Ph; b R1 = Ph, R2 = 2-Py; c R1 = 4-MeOC6H4, R2 = 2-Py; d R1 = Ph, R2 = 4-MeOC6H4
9a–d
B-(8a–d)-NH
1215

The 1H NMR spectra of triazines 9a-d show resonance signals for the aliphatic (1.59-1.90 ppm) as well
as aromatic and heteroaromatic fragments (6.86-8.85 ppm), while the 13C NMR spectra of these compounds
show characteristic carbon atom signals [17]. The mass spectra display molecular ion peaks.
X-ray structural analysis was carried out to confirm the structure of triazines 9a-d. These results
indicated that triazine 9c forms monoclinic crystals with space group P21/c (Fig. 2). No significant deviations
were found for the bond lengths and angles from standard values [18]. The triazine and imidazole rings are
planar. The deviations of the ring atoms from the mean planes do not exceed 0.014 Å. The dihedral angle
between the planes of the five- and six-membered azaheterocycles is 78.63°.
Fig. 2. The molecular structure of 9c with representation of the hydrogen atoms as thermal vibration ellipsoids
of 50% probability.
Thus, a new method is proposed for the preparation of previously unreported heterocycles by the
uncatalyzed C–C coupling of aldonitrones and 1,2,4-triazines.
EXPERIMENTAL
The IR spectra were recorded for neat samples on a Perkin Elmer Spectrum One B FTIR spectrometer
(DRA). The 1H NMR (400 MHz) and 13C NMR spectra (100 MHz, APT mode) were recorded on a Bruker Avance
1
13
II spectrometer in 1:1 DMSO-d6–CCl4 (for the H NMR spectra) and DMSO-d6 (for the C NMR spectra) with
TMS as internal standard. The ESI mass spectra were recorded on a Bruker Daltonics micrOTOF-Q II
spectrometer. The elemental analysis was carried out on a Perkin Elmer 2400-II CHNS/O analyzer. The melting
points were measured on a Boetius hot stage apparatus. The Rf values were obtained on Macheray-Nagel
Alugram Sil G/UV-254 plates. Merck silica gel (0.063-0.200 mm) was used for column chromatography.
The solvents were purified and dried by standard methods. s-BuLi (1.3 M in 92:8 cyclohexane–hexane
mixture) and DDQ from Alfa Aesar were used in the work.
2-Phenyl-1,4-diazaspiro[4,5]decane-1,3-diene 4-oxide (1) [21], 3,6-diphenyl-1,2,4-triazine 4-oxide (3)
[22], 3,6-diphenyl-1,2,4-triazine (7a) [23], 6-phenyl-3-(2-pyridyl)-1,2,4-triazine (7b), 6-(4-methoxyphenyl)-
3-(2-pyridyl)-1,2,4-triazine (7d) [24], 3-(4-methoxyphenyl)-6-phenyl-1,2,4-triazine (7c) [25] were prepared
according to literature procedures.
1216

Lithium derivatives 4-OLi and (8a-d)-NLi (General Method). 1.3 M s-BuLi solution (0.920 ml,
1.2 mmol) was added with vigorous stirring to a solution of 2-phenyl-1,4-diazaspiro[4,5]decane-1,3-diene
4-oxide (1) (0.228 g, 1.0 mmol) in THF (6 ml) under an argon atmosphere at -70°C. The reaction mixture was
stirred for 10 min at -70°C. A solution of the corresponding triazine 3 or 7a-d (1.2 mmol) in a minimal amount
of THF was added to the solution of the formed lithium derivative 2. The reaction mixture, which was a solution
of the respective intermediate 4-OLi or (8a-d)-NLi, was warmed to room temperature and stirred for an
additional 2 h.
Triazines 5 and 9a-d (General Method). Water (0.02 ml, 1.0 mmol) was added to the previously
prepared solution of lithium derivative 4-OLi or (8a-d)-NLi cooled to 0°C, and the reaction mixture was stirred
for 15 min at room temperature. The mixture was concentrated in vacuum. Triazines 5 and 9a-d were isolated
by column chromatography.
2-(3,6-Diphenyl-1,2,4-triazin-5-yl)-3-phenyl-1,4-diazaspiro[4,5]decane-1,3-diene 1-Oxide (5). Yield
0.376 g (82%). Yellow powder, mp 166-168°C. Rf 0.2 (hexane–EtOAc, 4:1). IR spectrum, ν, cm-1: 652, 690,
1
737, 1002, 1025, 1342, 1385, 1415, 1446, 1506, 1557, 1606 (C=N), 2853, 2929, 2940, 3060. Н NMR
spectrum, δ, ppm: 1.38-1.45 (3Н, m) and 1.72-1.88 (7Н, m, (CH2)5); 7.29-7.40 (4Н, m, Н Ph); 7.44-7.51 (4Н,
m, Н Ph); 7.52-7.58 (3Н, m, Н Ph); 7.61-7.66 (2Н, m, Н Ph); 8.28-8.32 (2Н, m, Н Ph). 13C NMR spectrum,
δ, ppm: 22.4 (CH2); 24.0 (CH2); 34.0 (CH2); 103.7; 127.0 (CH); 127.5 (CH); 127.7 (CH); 128.3 (CH); 128.5
(CH); 128.8 (CH); 129.9 (CH); 130.7 (CH); 131.2; 131.7 (CH); 132.8; 133.6; 133.9; 144.9; 156.0; 160.6; 163.6.
Found, m/z: 460.2086 [M+H]+. C29H26N5O. Calculated, m/z: 460.2132. Found, %: С 75.64; H 5.67; N 15.09.
C29H25N5O. Calculated, %: С 75.80; H 5.48; N 15.24.
2-(3,6-Diphenyl-1,2,4-triazin-5-yl)-3-phenyl-1,4-diazaspiro[4,5]decane-1,3-diene (9a). Yield 0.377 g
(85%). Yellow powder, mp 173-175°C. Rf 0.2 (hexane–EtOAc, 9:1). IR spectrum, ν, cm-1: 558, 649, 677, 950,
1
985, 1320, 1371, 1445, 1486, 1499, 1607 (C=N), 2846, 2923, 3058. Н NMR spectrum, δ, ppm: 1.59-1.85
(10Н, m, (CH2)5); 7.21-7.32 (6Н, m, H Ph); 7.38-7.43 (4Н, m, H Ph); 7.52-7.57 (3Н, m, H Ph); 8.39-8.43 (2Н,
13
m, H Ph). C NMR spectrum, δ, ppm: 23.2 (CH2); 24.6 (CH2); 32.9 (CH2); 106.0; 127.6 (2CH); 127.9 (CH);
128.1 (CH); 128.7 (CH); 128.8 (CH); 129.4; 129.9; 130.8; 131.6 (CH); 133.3; 133.6; 150.5; 155.7; 160.1; 160.4;
161.9. Found, m/z: 444.2147 [M+H]+. C29H26N5. Calculated, m/z: 444.2183. Found, %: С 78.67; H 5.68; N 15.96.
C29H25N5. Calculated, %: С 78.53; H 5.68; N 15.79.
3-Phenyl-2-[6-phenyl-3-(2-pyridyl)-1,2,4-triazin-5-yl]-1,4-diazaspiro[4,5]decane-1,3-diene
(9b).
Yield 0.377 g (80%). Yellow powder, mp 153-156°C. Rf 0.2 (hexane–EtOAc, 3:2). IR spectrum, ν, cm-1: 565,
1
676, 696, 762, 949, 985, 1074, 1386, 1487, 1624 (C=N), 2851, 2926, 3057. Н NMR spectrum, δ, ppm:
1.63-1.85 (10Н, m, (CH2)5); 7.23-7.43 (10Н, m, H Ph); 7.58-7.61 (1Н, m, H Py); 7.99-8.02 (1Н, m, H Py); 8.45-
8.48 (1Н, m, H Py); 8.82-8.83 (1Н, m, H Py). 13C NMR spectrum, δ, ppm: 23.4 (CH2); 24.8 (CH2); 33.0 (CH2);
106.3; 124.0 (CH); 125.9 (CH); 127.7 (CH); 128.2 (CH); 128.5 (CH); 129.1 (CH); 129.9 (CH); 130.3 (CH);
130.6; 133.2; 137.3 (CH); 150.1 (CH); 151.2; 151.8; 156.4; 160.5 (2С); 161.9. Found, m/z: 445.2180 [M+H]+.
C28H25N6. Calculated, m/z: 445.2135. Found, %: С 75.25; H 5.53; N 18.68. C28H24N6. Calculated, %: С 75.65;
H 5.44; N 18.90.
2-[6-(4-Methoxyphenyl)-3-(2-pyridyl)-1,2,4-triazin-5-yl]-3-phenyl-1,4-diazaspiro[4,5]decane-1,3-di-
ene (9c). Yield 0.370 g (78%). Yellow powder, mp 159–162°C. Rf 0.15 (hexane–EtOAc, 2:3). IR spectrum, ν,
cm-1: 693, 784, 948, 985, 1076, 1252, 1365, 1415, 1462, 1605 (C=N), 2853, 2927, 3055. 1Н NMR spectrum, δ,
ppm (J, Hz): 1.72-1.78 (6Н, m) and 1.84-1.90 (4Н, m, (CH2)5); 3.83 (3Н, s, OCH3); 6.86 (2Н, d, 3J = 8.8, H Ar);
3
7.23-7.29 (4Н, m, Н Ph); 7.34 (2Н, d, J = 8.8, H Ar); 7.40-7.43 (1Н, m, H Ph); 7.60-7.64 (1Н, m, H Py);
13
8.01-8.04 (1Н, m, H Py); 8.46-8.50 (1Н, m, H Py); 8.84-8.87 (1Н, m, H Py). C NMR spectrum, δ, ppm: 23.3
(CH2); 24.7 (CH2); 32.9 (CH2); 55.1 (CH3); 106.1; 113.8 (CH); 123.6 (CH); 125.2; 125.4 (CH); 127.4 (CH);
128.1 (CH); 130.0 (CH); 130.5 (CH); 130.6; 136.9 (CH); 149.8 (CH); 150.6; 151.8; 155.6; 159.9; 160.5; 160.7;
161.7. Found, m/z: 475.2261 [M+H]+. C29H27N6O. Calculated, m/z: 475.2241. Found, %: С 73.51; H 5.65;
N 17.55. C29H26N6O. Calculated, %: С 73.40; H 5.52; N 17.71.
1217

2-[3-(4-Methoxyphenyl)-6-phenyl-1,2,4-triazin-5-yl]-3-phenyl-1,4-diazaspiro[4,5]decane-1,3-diene
(9d). Yield 0.355 g (75%). Yellow powder, mp 181–185°C. Rf 0.15 (hexane–EtOAc, 4:1). IR spectrum, ν, cm-1:
695, 731, 845, 984, 1028, 1172, 1253, 1277, 1395, 1461, 1489, 1605 (C=N), 2851, 2914, 2925, 2937, 3001,
3056. 1Н NMR spectrum, δ, ppm (J, Hz): 1.63-1.88 (10Н, m, (CH2)5); 3.91 (3Н, s, OCH3); 7.06 (2Н, d, 3J = 8.8,
3
H Ar); 7.28-7.43 (10Н, m, H Ph); 8.38 (2Н, d, J = 8.8, H Ar). 13C NMR spectrum, δ, ppm: 23.1 (CH2); 24.6
(CH2); 32.9 (CH2); 55.1 (CH3); 105.9; 114.3 (CH); 125.9; 127.5 (CH); 127.8 (CH); 128.1 (CH); 128.5 (CH);
128.7 (CH); 129.2 (CH); 129.4 (CH); 129.9; 133.4; 150.3; 154.9; 160.1 (2С); 161.9; 162.3. Found, m/z:
474.2292 [M+H]+. C30H28N5O. Calculated, m/z: 474.2288. Found, %: С 76.44; H 5.66; N 14.66. C30H27N5O.
Calculated, %: С 76.09; H 5.75; N 14.79.
2-(4-Oxido-3,6-diphenyl-1,2,4-triazin-5-yl)-3-phenyl-1,4-diazaspiro[4,5]decane-1,3-diene 1-Oxide
(6). A solution of DDQ (0.273 g, 1.2 mmol) in THF (5 ml) was added to a previously prepared solution of
4-OLi cooled to 0°C, and the mixture was stirred for 15 min. The reaction mixture was then filtered through an
alumina layer and evaporated. The residue was purified by column chromatography. Yield 0.308 g (65%).
Light-yellow powder, mp 172-175°C. Rf 0.15 (hexane–EtOAc, 4:1). IR spectrum, ν, cm-1: 618, 672, 688, 994,
1021, 1261, 1338, 1416, 1483, 1563 (C=N), 2855, 2925, 3052. 1Н NMR spectrum, δ, ppm: 1.17-1.20 (1Н, m),
1.37-1.41 (1Н, m), 1.50-1.54 (1Н, m), 1.78-1.88 (6Н, m), and 1.97-2.01 (1Н, m, (CH2)5); 7.33-7.39 (6Н, m,
Н Ph); 7.43-7.48 (2Н, m, Н Ph); 7.55-7.63 (5Н, m, Н Ph); 8.24-8.28 (2Н, m, Н Ph). 13C NMR spectrum, δ, ppm:
22.6 (CH2); 22.7 (CH2); 24.2 (CH2); 33.9 (CH2); 34.8 (CH2); 103.9; 126.5 (CH); 127.6 (CH); 127.8; 128.2
(CH); 128.4; 128.6 (CH); 129.0 (CH); 129.8 (CH); 130.8 (CH); 131.3; 131.6 (CH); 131.8 (CH); 132.7; 134.1;
156.5; 157.8; 163.1. Found, m/z: 476.2143 [M+H]+. C29H26N5O2. Calculated, m/z: 476.2081. Found, %:
С 73.32; H 5.34; N 14.66. C29H25N5O2. Calculated, %: С 73.25; H 5.30; N 14.73.
X-ray Structural Analysis of Triazines 5 and 9c. Monocrystals of triazines 5 and 9c were grown by
slow evaporation of the corresponding solutions in ether. The unit cell parameters for the orthorhombic crystals
of triazine 5 are as follows: a 17.2482(11), b 9.5284(7), c 15.0868(9) Å, β 90.00°, V 2479.5(3) Å3, F(000) 968,
μ 0.077, dcalc 1.231, Z 4, space group Pna21. The unit cell parameters for the monoclinic crystals of triazine 9c are
as follows: a 10.8579(7), b 10.5150(10), c 21.732(2) Å, β 102.199(7)°, V 2425.1(4) Å3, F(000) 1000, μ 0.082, dcalc
1.300, Z 4, space group P21/c. The experimental sets of reflections were measured at 295(2) K on an Xcalibur 3
diffractometer using λMo radiation, graphite monochromator, ω-scanning, and scanning step 1°. The structures
were solved by the direct method using the SHELXS97 program [26] and refined using the full-matrix
anisotropic method of least squares (isotropic method for hydrogen atoms) and the SHELXL97 program [27].
The hydrogen atoms were located using the electron density peaks and included in the refinement using the"
rider" model with dependent thermal parameters. The complete data of the X-ray structural studies were
deposited at the Cambridge Crystallographic Data Center: deposit CCDC 865991 for triazine 5 and deposit
CCDC 865992 for triazine 9c.
This work was carried out with the financial support the Grants Council of the President of the Russian
Federation (grants MK-1901.2011 and NSh-5505.2012.3), Russian Foundation for Basic Research (grant 10-03-
00756-a), Civilian Research and Development Foundation (CRDF) (REC 005), and Ural Federal University
Development Program.
The team of authors expresses its gratitude to P. A. Slepukhin for carrying out the X-ray diffraction
structural analyses and to O. S. El'tsov, I. S. Kovalev, and T. S. Shtukina for carrying out the NMR experiments
and registration of the mass spectra.
REFERENCES
1.
A. Meijere and F. Diederich, Metal-Catalyzed Cross-Coupling Reactions, 2nd ed., Wiley-VCH,
Weinheim (2004).
1218

2.
3.
J. J. Li and G. W. Gribble, Palladium in Heterocyclic Chemistry, Pergamon Press, Oxford (2000).
Modern Trends in Funtionalization of C–H Bonds in Arenes and Hetarenes, in: Abstracts of Symposium
International Congress on Organic Chemistry, Kazan, Russia (2011), pp. 441-479.
O. N. Chupakhin, V. N. Charushin, and H. C. van der Plas, Nucleophilic Aromatic Substitution of
Hydrogen, Academic Press, San Diego (1994).
4.
5.
6.
7.
V. N. Charushin and O. N. Chupakhin, Pure Appl. Chem., 76, 1621 (2004).
J. Suhadolnik and R. Ravichandran, US Pat. Appl. 4972009.
P. Moeckel, W. Weissflog, E. Roll, L. Bauch, G. Lehmann, J. Bauer, H. Kramer, W. Guenter, and D.
Bassler, Ger. (East) Pat. Appl. 282771.
8.
9.
10.
C. W. Ellwood and A. Y. Tikhonov, WO Pat. Appl. 9803479.
P. L. Croot and K. A. Hunter, Anal. Chim. Acta, 406, 289 (2000).
P. B. Iveson, C. Rivière, D. Guillaneux, M. Nierlich, P. Thuéry, M. Ephritikhine, and C. Madic, Chem.
Commun., 1512 (2001).
11.
12.
V. Maheshwari, D. Bhattacharyya, F. R. Fronczek, P. A. Marzilli, and L. G. Marzilli, Inorg. Chem., 45,
7182 (2006).
M. A. Voinov, T. G. Shevelov, T. V. Rybalova, Yu. V. Gatilov, N. V. Pervukhina, A. B. Burdukov, and
I. A. Grigor'ev, Organometallics, 26, 1607 (2007).
13.
14.
15.
16.
P. Beak and D. B. Reitz, Chem. Rev., 78, 275 (1978).
D. N. Kozhevnikov, V. L. Rusinov, and O. N. Chupakhin, Adv. Heterocycl. Chem., 82, 261 (2003).
M. O. Senge and I. Bischoff, Eur. J. Org. Chem., 1735 (2001).
O. N. Chupakhin, I. A. Utepova, I. S. Kovalev, V. L. Rusinov, and Z. A. Starikova, Eur. J. Org. Chem.,
857 (2007).
17.
18.
L. D. Field, S. Sternhell, and J. R. Kalman, Organic Structures from Spectra, John Wiley and Sons,
Chichester (2008).
F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen, and R. Taylor, J. Chem. Soc., Perkin
Trans. 2, S1 (1987).
19.
20.
21.
22.
M. Makosza, Chem. Soc. Rev., 39, 2855 (2010).
M. Makosza, Synthesis, 2341 (2011).
I. A. Kirilyuk, I. A. Grigor'ev, and L. B. Volodarskii, Izv. Akad. Nauk SSSR, Ser. Khim., 2113 (1991).
D. N. Kozhevnikov, V. N. Kozhevnikov, V. L. Rusinov, O. N. Chupakhin, E. O. Sidorov, and
N. A. Klyuev, Zh. Org. Khim., 34, 423 (1998).
23.
24.
V. N. Kozhevnikov, M. M. Ustinova, P. A. Slepukhin, A. Santoro, D. W. Bruce, and
D. N. Kozhevnikov, Tetrahedron Lett., 49, 4096 (2008).
V. N. Kozhevnikov, D. N. Kozhevnikov, O. V. Shabunina, V. L. Rusinov, and O. N. Chupakhin,
Tetrahedron Lett., 46, 1791 (2005).
25.
26.
T. V. Saraswathi and V. R. Srinivasan, Tetrahedron, 33, 1043 (1977).
G. M. Sheldrick, SHELXS97 Program for the Solution of Crystal Structure, University of Göttingen
(1997).
27.
G. M. Sheldrick, SHELXL97 Program for the Refinement of Crystal Structure, University of Göttingen
(1997).
1219