Reaction of 3-acetoxy-(2,3),(19β,28)-diepoxyoleanane with cyclic and linear amines

Article abstract of DOI:10.1007/s10600-007-0067-4

A mixture of diastereomeric 3-acetoxy-(2,3),(19β,28)-diepoxyoleananes was prepared via reaction of 3-acetoxy-19β,28-epoxyolean-2-ene with m-chloroperbenzoic acid. Directed rearrangement of these formed 2β-acetoxy-19β,28-epoxyolean-3-one whereas heating of them in amines produced oleanane-type enamines.

Full text of DOI:10.1007/s10600-007-0067-4

Chemistry of Natural Compounds, Vol. 43, No. 2, 2007
REACTION OF 3-ACETOXY-(2,3),(19
β,28)-DIEPOXYOLEANANE
WITH CYCLIC AND LINEAR AMINES
I. A. Tolmacheva,1 L. N. Shelepen′kina,1 A. S. Shashkov,2
V. V. Grishko,1 V. A. Glushkov,1 and A. G. Tolstikov1
UDC 547.597:542.943
+542.951.9+542.954
A mixture of diastereomeric 3-acetoxy-(2,3),(19β,28)-diepoxyoleananes was prepared via reaction of
3-acetoxy-19β,28-epoxyolean-2-enewith m-chloroperbenzoic acid. Directedrearrangementoftheseformed
2β-acetoxy-19β,28-epoxyolean-3-one whereas heating of them in amines produced oleanane-type enamines.
Key words: triterpenoids, oleanane, allobetulone, enamines, 2β-acetoxyketone.
Allobetulin and several of its derivatives belong to a group of pentacyclic triterpenoids that is promising for developing
highly effective viricides and other medicinal preparations [1]. Allobetulin is highly active toward flu B virus [2].
28-Oxoallobetulone prepared from it inhibits effectively flu A virus [3]. Among allobetulin derivatives, compounds with
antifeedant [4] and biomarker [5] properties have been found.
In searches for compounds with antiviral and other activities, we synthesized new N-containing oleanane-type
triterpenoids based on transformations of allobetulone (19β,28-epoxy-18α-olean-3-one).
Reaction of allobetulone (1) with acetic anhydride or isopropenylacetate in the presence of catalytic amounts of conc.
H SO [6] produced 3-acetoxy-19β,28-epoxyolean-2-ene (2), the PMR spectrum of which contained a singlet at 2.08 ppm and
2
4
a doublet of doublets at 5.09 ppm corresponding to C-3 acetyl protons and the C-2 olefinic proton. Oxidation of 2 by
m-chloroperbenzoic acid under standard conditions [7, 8] formed 3-acetoxy-(2,3),(19β,28)-diepoxyoleanane as a mixture of
diastereomers 3a and 3b. This was confirmed by doubled signals in the PMR spectrum for the C-2 proton at 4.49 (3b) and
5.56 ppm (3a) and the acetyl protons at 2.03 (3b) and 2.09 ppm (3a). The integrated intensities of these signals established that
the isomers 3a and 3b were synthesized in a 3:2 ratio.
30
29
20 21
19
13
O
O
11
26
17
15
25
9
28
1. (CH CO) O, H SO
4
1
3
2
2
10
7
3
27
2.
OAc, H SO
4
5
2
O
AcO
24
23
1
2
O
CH COO
3
m-ClC H CO H
6
4
3
O
O
+
AcO
O
AcO
4
3a
3b
1) Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, 614013, Perm′, ul. Koroleva, 3, fax
(342) 237 82 62, e-mail: grishko@iegm.ru; 2) N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences,
119991, Moscow, Leninskii prosp., 47. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 127-131, March-April,
2007. Original article submitted November 22, 2006.
0009-3130/07/4302-0153 ©2007 Springer Science+Business Media, Inc.
153

C 30
C 29
C 32
O 2
C 2
C 20
C 19
C 31
O 3
C 12
C 13
C 18
C 17
C 11
C 9
C 1
C 21
O 4
C 27
C 22
O 1
C 25
C 10
C 14
C 15
C 16
C 3
C 24
C 8
C 28
C 5
C 6
C 4
C 26
C 7
C 23
Fig. 1. Molecular structure of 2β-acetoxy-19β,28-epoxyolean-3-one (4).
New N-containing allobetulone derivatives were synthesized via reaction of a mixture of epoxides 3a and 3b with
methyl esters of biogenic amino acids and cyclic and linear amines with heating in organic solvents. Regardless of the amine
used and the solvent, the reaction proceeded under the given conditions to form a single rearrangement product of 3a and 3b,
acetoxyketone 4, the IR spectrum of which contained vibrational bands for carbonyl (1700 cm−1) and ester (1740 cm−1) groups.
Fusion of 3a and 3b with amino-acid esters at 180-200°C also gave 4.
13
The structure of 4 was proposed based on PMR and C NMR data (Table 1), which were integrated using two-
1
1
13
1
1
1
dimensional (2D) H— H (COSY) and C— H (TOCSY, ROESY, HSQC, HMBC) NMR. Thus, PMR and H— H (COSY)
1
1
NMR spectra identified the protons on C-28 (3.78 and 3.46 ppm) and C-19 (3.54 ppm). The H— H (COSY) NMR spectrum
identified the signals of the C-1 protons in ring A with chemical shifts (CS) 2.20 and 1.67 ppm by their correlation with the
C-2 proton, which appeared as a weak-field doublet of doublets with CS 5.65 ppm (J = 11.5 Hz, J = 8.3 Hz). The nature
aa
ac
of the splitting of the H-2 signal, which was geminal to the acetoxy, indicated that the acetoxywas oriented equatoriallybecause
the observed SSCC were typical of an axial proton of a cyclohexyl ring with the boat or slightly distorted boat conformation.
1
1
The 2D H— H (COSY) NMR spectrum of 4 contained cross peaks due to spin—spin coupling of protons through two or three
σ-bonds and cross peaks due to through-space spin—spin couplings H(19)/H(21), H(19)/H(22), and H(28)/H(22). The 2D
13
1
C— H(HMBC) NMRspectrum showed cross peaks consistent with the proposed structure C(2)/H(1), C(3)/H(1), H(3)/H(23),
C(3)/H(24), C(4)/H(2), C(9)/H(25), C(9)/H(26), C(15)/H(27), C(18)/H(28), C(28)/H(19), C(19)/H(28), C(19)/H(29),
C(22)/H(28), C(29)/H(30), C(31)/H(32). The absolute configuration of 2β-acetoxy-19β,28-epoxyolean-3-one was confirmed
by an x-ray structure analysis (Fig. 1).
Examples of kinetic separation of racemic epoxides of enol esters of monocyclic compounds with formation of
enantiomerically enriched α-acyloxyketones in the presence of chiral Lewis acids have been reported [9]. In our instance,
rearrangement of lupane derivatives 3a and 3b into the corresponding acetoxyketone 4 occured at elevated temperatures. This
process typically was highly stereoselective. Because of steric hindrances from the geminal C-4 methyls, the final product
2β-acetoxyketone 4 was formed exclusively. The observed high (76%) chemical yield of 4 indicated that both diastereomeric
epoxides 3a and 3b were involved in the rearrangement. If it is assumed that 4 formed from 3a through intermediates I and
1
I , then transformation oftheseconddiastereomer 3bgavetheanalogousproduct4, most probablythrough enolization involving
2
formation of the corresponding intermediates I -I .
3
6
H
_ H
O
H
O
_
O
H C
3
O
O
O
O
O
+
+
O
O
H C
3
O
O
H C
3
I
4
I
1
CH CO
3
2
3a
H
_
O
H
_
O
_
O
H C
3
O
O
O
O
O
O
O
O
+
H C
3
H C
3
HO
H C
3
O
CH CO
3
+
O
H
I
4
3b
I
3
I
5
I
6
Scheme 1.
154

TABLE 1. PMR and 13C NMR Data for 4 and 5b (500 MHz, CDCl3, δ, ppm, J/Hz)
4
5
C atom
δC
δH
δC
δH
1
47.24
1.67 (1H, dd, J1 = 13.2, J2 = 8.0);
134.73
5.99 (1H, s)
2.20 (1H, br.t, J = 13.4)
2
3
4
5
6
7
71.31
212.40
46.38
52.05
19.86
32.42
5.65 (1H, dd, J1 = 11.5, J2 = 8.3)
144.65
201.60
45.41
52.38
19.44
32.66
-
-
-
-
-
1.80 (1H, dd, J1 = 9.9, J2 = 3.1)
1.42-1.50 (2H)
1.39-1.51 (2H)
1.46-1.50 (1H)
1.42-1.50 (2H)
1.22-1.25 (1H);
1.54-1.56 (1H)
-
8
9
10
11
40.42
50.40
37.38
22.13
-
1.57 (1H, dd, J1 = 13.2, J2 = 2.5)
-
40.97
45.76
38.18
21.78
1.60 (1H, br.d, J = 13.0)
-
1.29-1.33 (1H);
1.38-1.43 (1H)
0.91-0.96 (1H);
1.64-1.70 (1H)
1.48-1.52 (1H)
-
1.33-1.43 (1H);
1.65 (1H, dm, J = 15.0)
0.98-1.08 (1H);
1.74 (2H, dm, J = 14.0)
1.51-1.55 (1H)
-
12
26.41
26.47
13
14
15
34.47
40.78
26.41
34.42
41.22
26.36
1.15 (1H, dm, J = 10.9);
1.56 (1H)
1.00-1.08 (1H);
1.53-1.62 (1H)
1.31-1.37 (1H);
1.42-1.51 (1H)
-
1.48-1.54 (1H)
3.55 (1H, s)
-
16
26.19
1.31-1.36 (1H);
1.42-1.50 (1H)
-
1.48-1.53 (1H)
3.54 (1H, s)
26.23
17
18
19
20
21
41.47
46.75
87.90
36.28
32.71
41.44
46.72
87.82
36.24
33.07
-
1.25 (1H, dd, J1 = 13.9, J2 = 6.1);
1.48-1.55 (1H)
1.28-1.34 (1H);
1.41-1.46 (1H)
1.19 (3H, s)
1.39-1.52 (2H)
22
36.73
36.70
1.27-1.34 (1H);
1.37-1.46 (1H)
1.16 (3H, s)
1.06 (3H, s)
0.98 (3H, s)
23
24
25
26
27
28
29.09
19.35
18.76
15.05
13.42
71.25
29.05
20.83
20.99
15.91
13.35
71.23
1.09 (3H, s)
0.81 (3H, s)
0.97 (3H, s)
0.96 (3H, s)
1.03 (3H, s)
0.96 (3H, s)
3.46 (1H, d, J = 8.0);
3.77 (1H, d, J = 8.0)
0.80 (3H, s)
3.46 (1H, d, J = 7.8);
3.78 (1H, d, J = 7.8)
0.81 (3H, s)
29
30
31
24.56
28.79
170.26
24.51
28.76
49.38
0.94 (3H, s)
0.94 (3H, s)
-
2.52-2.56 (1H, m);
2.86-2.89 (1H, m)
3.75-3.84 (2H, m)
3.75-3.84 (2H, m)
2.52-2.56 (1H, m);
2.86-2.89 (1H, m)
32
33
34
20.78
-
-
2.15 (3H, s)
66.68
66.68
49.38
-
-
When a cyclic or linear amine was used simultaneouslyas the reagent and solvent [8], heating caused the reaction with
3a and 3b to form enamines 5a-e (Scheme 2). The PMR spectra of 5a-e contained signals characteristic of protons of the
1
1
N-containing substituent and the C-1 vinyl proton. The structures of the enamines were confirmed by2D H— H (COSY) and
13
1
C— H (HSQC, HMBC) NMR spectra using the morpholine derivative 5b as an example (Table 1). Thus, according to the
1
1
H— H (COSY) PMR spectrum of 5b, signals with CS 2.53-2.56, 2.86-2.89, and 3.75-3.84 ppm corresponded to protons of
155

the morpholine substituent. The singlet characteristic ofthe vinyl proton (CH-1) appeared at 5.98 ppm. Cross peaks were found
13
1
in the 2D C— H (HMBC) NMR spectrum for through-space spin—spin couplings C(5)/H(1), C(9)/H(1), C(13)/H(27),
C(17)/H(19), C(18)/H(28), C(19)/H(29), C(19)/H(30), C(21)/H(19), C(22)/H(28), C(26)/H(24).
_
H
R R NH
1 2
R R N
1 2
R R N
1 2
+
O
O
H C
3
O
O
O
H C
3
_
O
H C
3
_
3a, b
4
+
O
-AcOH
O
O
O
5a - e
I
2
I
7
I
8
5a: R1R2 = -(CH2)5-; 5b: R1R2 = -(CH2)2O(CH2)2-; 5c: R1 = C6H5CH2-, R2 = H; 5d: R1 = C6H13-, R2 = H; 5e: R1 = C6H11-, R2 = H
Scheme 2.
Assuming that the reaction of 3a and 3b with the more nucleophilic aliphatic amines also occurred through formation
of rearrangement product 4, we synthesized enamine 5b starting from 2β-acetoxy-19β,28-epoxyolean-3-one (4). Boiling 4 in
morpholine produced 2-morpholino-19β,28-epoxyolean-1-en-3-one (5b) in the same chemical yield as for the reaction with
epoxides 3a and 3b. Apparentlythe synthesis oftheN-containing derivatives 5a-e (Scheme 2) from 3a and 3b occurred through
formation from the rearrangement product 4 of intermediates I , I , and I and final elimination of acetic acid to form the
2
7
8
oleanane enamines 5a-e.
EXPERIMENTAL
1
1
13
1
IR spectra were recorded on a UR-20 spectrophotometer in mineral oil; 2D H— H (COSY) and C— H (TOCSY,
ROESY, HSQC, HMBC) NMR spectra of4 and 5bin CDCl , on a Bruker DRX-500 spectrometer (working frequency500 MHz,
3
internal standard HMDS). PMRspectra in CDCl wererecordedon a Varian Mercuryplus-300spectrometer (workingfrequency
3
300 MHz, internal standard HMDS). Melting points were measured on PTP instrument. Specific optical rotations in CHCl
3
were determined on a Perkin—Elmer model 341 polarimeter at 589 nm. X-ray structure analysis of 4 was performed on a
Syntex P2 automated four-circle diffractometer (Mo Kα-radiation, λ = 0.71073 Å, graphite monochromator, θ/2θ scanning,
1
2θ < 54°). Elemental analyses (C, H, N) were carried out using a Carlo Erba Model 1106 analyzer. Elemental analyses agreed
with those calculated.
Column chromatography was performed over silica gel (Merck 60-200 µm) at a 1:50 compound:sorbent ratio with
individual eluents for each compound. TLC used Sorbfil (Russia) plates. Compounds were developed by spraying with
phosphomolybdic acid (20%) in ethanol with subsequent heating at 100-120°C for 2-3 min. Anhydrous solvents were prepared
by standard methods [10]. Allobetulone (1) was prepared by oxidation of allobetulin [11] using standard Jones reagent [12] in
acetone.
3-Acetoxy-19β,28-epoxyolean-2-ene (2) was prepared by two methods. a) A solution of 1 (2 g, 4.5 mmol) in
anhydrous CCl (50 mL) was treated with acetic anhydride (2 mL) and conc. H SO (2 drops). The mixture was stirred at room
4
2
4
temperature with TLC monitoring. Solvent was distilled in vacuo. The solid was recrystallized from ethanol:chloroform, yield
1.4 g (70%).
b) A solution of 1 (2 g, 4.5 mmol) in anhydrous CCl (50 mL) was treated with isopropenylacetate (4 mL) and conc.
4
H SO (2 drops). The mixture was stirred at room temperature with TLC monitoring. Solvent was distilled in vacuo. The solid
2
4
wasrecrystalizedfrom ethanol:chloroform, yield1.5g(73%), mp262-264°C(ethanol:chloroform), R 0.56(hexane:ethylacetate,
f
22
−1
5:1), [α]
+56.2° (c 1.5, CHCl ). IR spectrum (ν, cm ): 1750 (OCOCH ).
D
3
3
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.74, 0.87, 0.90 (3H each, s, CH ), 0.85, 0.94 (6H each, s, 2CH ),
3
3
3
2.08 (3H, s, OCOCH ), 3.39 and 3.73 (1H each, d, J = 7.8, CH -28), 3.48 (1H, s, CH-19), 5.09 (1H, dd, J = 6.6, J = 1.8,
3
2
1
2
CH-2).
156

3-Acetoxy-(2,3),(19β,28)-diepoxyoleanane (3a and 3b). A solution of 2 (2.5 g, 5.2 mmol) in CH Cl (30 mL) was
2
2
stirred on a magnetic stirrer and treated with m-chloroperbenzoic acid (2.5 g, 14.5 mmol) in diethylether (20 mL). The mixture
was stirred for 24 h at room temperature with TLC monitoring. When the reaction was finished the mixture was washed with
aqueous NaOH (10%) to remove residual m-chloroperbenzoic acid. The organic layer was separated and dried over Na SO .
2
4
The solvent was removed in vacuo. The product was purified by column chromatography with elution by
hexane:ethylacetate:chloroform (10:1:2), yield
2
g
(77%), mp 258-260°C (ethanol:chloroform),
R
0.4
f
18
−1
(hexane:ethylacetate:chloroform, 10:1:2), [α]
+20.23° (c 1.7, CHCl ). IR spectrum (ν, cm ): 1750 (OCOCH ).
D
3
3
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.73, 0.83, 0.87, 0.97, 1.04 (5 × 3H, 5s, 5CH ), 1.07 (1.8H, s, CH
3
3
3
of isomer 3a), 1.09 (1.2H, s, CH of isomer 3b), 1.13 (1.2H, s, CH of isomer 3b), 1.16 (1.8H, s, CH of isomer 3a), 2.03 (1.2H,
3
3
3
s, OCOCH of isomer 3b), 2.09 (1.8H, s, OCOCH of isomer 3a), 2.26 (0.6H, dd, J = 12.2, J = 6.0, CH-1 of isomer 3a), 2.46
3
3
1
2
(0.4H, dd, J = 12.5, J = 6.6, CH-1 of isomer 3b), 3.39 and 3.71 (2H, 2d, J = 7.8, CH -28), 3.47 (1H, s, CH-19), 4.49 (0.4H,
1
2
2
dd, J = 12.3, J = 6.6, CH-2 of isomer 3b), 5.56 (0.6H, dd, J = 13.2, J = 6.0, CH-2 of isomer 3a).
1
2
1
2
2β-Acetoxy-19β,28-epoxyolean-3-one (4). A mixture of 3a and 3b (0.5 g, 1 mmol) and morpholine (0.1 mL,
1.15 mmol) in benzene (50 mL) was refluxed with TLC monitoring. Solvent was distilled in vacuo. The solid was recrystallized
from ethanol:chloroform, yield 0.38 g (76%), mp 284-286°C (ethanol:chloroform), R 0.25 (hexane:ethylacetate, 5:1),
f
18
−1
[α]
+60.8° (c 1, CHCl ). IR spectrum (ν, cm ): 1700 (C=O), 1740 (COOCH ). Mass spectrum (EI, 70 eV, m/z, I , %):
D
3
3
rel
+
498 (53) [M] , 456 (47), 438 (25), 427 (100), 205 (53), 204 (33), 191 (48), 190 (22), 189 (33), 187 (41), 177 (44), 175 (30),
163 (31), 161 (28), 150 (20), 149 (70), 147 (30), 137 (29), 135 (55), 133 (35), 123 (34), 122 (21), 121 (66), 119 (41), 109 (58),
108 (23), 107 (64), 105 (34), 95 (84), 93 (46), 83 (30), 82 (28), 81 (81), 79 (26), 69 (91), 55 (57).
13
Table 1 gives the PMR and C NMR spectral data for 4.
General Method for Preparing C-2-Substituted 19β,28-Epoxyolean-1-en-3-ones (5a-e). Epoxide (3a and 3b,
1 mmol) was added to an amine (30 mmol) and refluxed for 16-20 h with TLC monitoring. The mixture was diluted with water.
The resulting precipitate was filtered off, dried, and purified by column chromatography with an individual eluent for each
compound. The products were crystallized from hexane:ethylacetate (10:1).
2-Piperidino-19β,28-epoxyolean-1-en-3-one (5a). Yield0.25g(47%), mp79-81°C, R 0.15(chloroform:ethylacetate,
f
18
−1
10:1), [α]
+147.41° (c 1.3, CHCl ). IR spectrum (ν, cm ): 1680 (C=O).
D
3
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.74, 0.88, 0.89, 0.90, 0.96, 0.98, 1.08 (7 × 3H, 7s, 7CH ), 2.39-2.47
3
3
(2H, m, piperidine), 2.68-2.75 (2H, m, piperidine), 3.39 and 3.72 (2H, 2d, J = 8.1, CH -28), 3.49 (1H, s, CH-19), 5.90 (1H, s,
2
CH-1).
2-Morpholino-19β,28-epoxyolean-1-en-3-one (5b). C H NO , yield 0.35 g (62%), mp 197-199°C, R 0.15
f
37 54
3
18
−1
(hexane:ethylacetate, 5:1), [α]
+118.47° (c 2.1, CHCl ). IR spectrum (ν, cm ): 1685 (C=O).
D
3
13
Table 1 gives the PMR and C NMR data for 5b.
Synthesis of 2-Morpholino-19β,28-epoxyolean-1-en-3-one (5b) from Acetoxyketone 4. A mixture of 4 (0.1 g,
0.2 mmol) and morpholine (2.5 mL, 30 mmol) was refluxed for several hours with monitoring byTLC. The mixture was diluted
with water. The resulting precipitate was filtered off, dried, and purified by column chromatography with elution by
hexane:ethylacetate (5:1), yield 0.063 g (60%).
2-Benzylamino-19β,28-epoxyolean-1-en-3-one (5c). C H NO , yield 0.35 g (64%), mp 296-298°C, R 0.25
f
37 54
2
18
−1
(chloroform:ethylacetate, 10:1), [α]
+41.70° (c 1.5, CHCl ). IR spectrum (ν, cm ): 1680 (C=O), 3400 br (NH).
D
3
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.71, 0.85, 0.95 (3 × 3H, 3s, 3CH ), 0.80, 0.84 (2 × 6H, s, 4CH ),
3
3
3
3.38 and 3.71 (2H, 2d, J = 7.5, CH -28), 3.44 (1H, s, CH-19), 5.00 (2H, s, CH C H ), 6.91 (1H, d, J = 7.2, CH-1), 7.23-7.44
2
2 6 5
(5H, m, arom.).
2-n-Hexylamino-19β,28-epoxyolean-1-en-3-one (5d). Yield 0.35 g (66%), mp 130-132°C, R 0.6 (hexane:ethanol,
f
18
−1
+72.8° (c 1.0, CHCl ). IR spectrum (ν, cm ): 1680 (C=O), 3350 br (NH).
10:1), [α]
D
3
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.74, 0.87, 0.88, 0.97, 1.02, 1.05, 1.09 (7 × 3H, 7s, 7CH ), 2.63-2.79
3
3
(2H, m, NHCH C H ), 3.40 and 3.72 (2H, 2d, J = 8.1, CH -28), 3.49 (1H, s, CH-19), 3.88 (1H, br.s, NH), 5.65 (1H, s, CH-1).
2
5
11
2
2-Cyclohexylamino-19β,28-epoxyolean-1-en-3-one (5e). C H NO , yield 0.3 g (59%), mp 180-181°C, R 0.4
f
36 58
−1
2
18
(hexane:ethanol, 10:1), [α]
+53.1° (c 1.0, CHCl ). IR spectrum (ν, cm ): 1680 (C=O), 3400 br (NH).
3
D
PMR spectrum (300 MHz, CDCl , δ, ppm, J/Hz): 0.75, 0.87, 0.88, 0.97, 1.02, 1.04, 1.08 (7 × 3H, 7s, 7CH ), 2.74-2.88
3
3
(1H, m, NHCHC H ), 3.39 and 3.72 (2H, 2d, J = 8.1, CH -28), 3.50 (1H, s, CH-19), 3.88 (1H, br.s, NH), 5.69 (1H, s, CH-1).
5
10
2
157

ACKNOWLEDGMENT
We would like to thank K. Yu. Suponitskii of the A. N. Nesmeyanov Institute of Elementorganic Compounds for
performing the x-ray structure analysis of 4 and staff of the Laboratory of Physical Chemical Methods of the ITC, UD, RAS for
technical help in recording the PMR and IR spectra. The work was supported by a grant of the RF President for state support
ofleading RF scientific schools (No. NSh-5812.2006.3)andtheRASPresidium Program DirectedSynthesisofCompoundswith
Given Properties and Development of Functional Materials Based on Them.
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