Adamantylazoles: XII. Alkylation of 1-R-tetrazole-5-thiones and 1-R-tetrazol-5-ones with tertiary alcohols in sulfuric acid

Article abstract of DOI:10.1134/S1070363209100235

1-R-Substituted tetrazole-5-thiones reacted with adamantan-1-ol in sulfuric acid to give mesoionic 1-R-3-(1-adamantyl)tetrazolium-5-thiolates, isomeric 1-R-5-(1-adamantylsulfanyl)tetrazoles, 1-R-4-(1-adamantyl) tetrazole-5-thiones, and 1-R-3-(1-adamantyl)

Full text of DOI:10.1134/S1070363209100235

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 10, pp. 2220–2229. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © A.V. Logvinov, I.N. Polyakova, E.L. Golod, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 10, pp. 1726–1734.
Adamantylazoles: XII.1 Alkylation of 1-R-Tetrazole-5-thiones
and 1-R-Tetrazol-5-ones with Tertiary Alcohols in Sulfuric Acid
A. V. Logvinova, I. N. Polyakovab, and E. L. Goloda
a St. Petersburg State Institute of Technology, Moskovskii pr. 26, St. Petersburg, 190013 Russia
e-mail: golod18@yandex.ru
b Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
Received November 20, 2008
Abstract—1-R-Substituted tetrazole-5-thiones reacted with adamantan-1-ol in sulfuric acid to give mesoionic
1-R-3-(1-adamantyl)tetrazolium-5-thiolates, isomeric 1-R-5-(1-adamantylsulfanyl)tetrazoles, 1-R-4-(1-ada-
mantyl)tetrazole-5-thiones, and 1-R-3-(1-adamantyl)-5-(1-adamantylsulfanyl)tetrazolium salts. Adamantylation
of 1-R-tetrazol-5-ones under analogous conditions afforded only the corresponding mesoionic 1-R-3-(1-
adamantyl)tetrazolium-5-olates. Mesoionic 1-R-3-tert-butyltetrazolium-5-thiolates and 1-R-3-tert-butyltetra-
zolium-5-olates were obtained by alkylation of the same substrates with tert-butyl alcohol in sulfuric acid.
DOI: 10.1134/S1070363209100235
We previously reported on the reaction of 1-phenyl-
1H-tetrazole-5-thione (Ia) with adamantan-1-ol in
strong acid, which led to the formation of mesoionic 3-
(1-adamantyl)-1-phenyltetrazolium-5-thiolate (IIa) and
tetrazolium salts as the major products [1]. The
formation of mesoionic compounds like IIa is not
typical of alkylation of 1-substituted tetrazole-5-
thiones [2], and such derivatives are usually obtained
by other methods [3–6]. In continuation of our studies
in this line, in the present work we examined acid-
catalyzed alkylation with adamantan-1-ol of 1-R-
tetrazole-5-thiones having different substituents on N1,
as well as of 1-R-tetrazol-5-ones which also possess an
exocyclic heteroatom with unshared electron pair.
(Scheme 1). The ratio of isomers IIb, IIIa, and IVa
was 77:19:4. Introduction of an electron-withdrawing
group into aromatic substituent affects electron density
distribution and could change properties of the entire
molecule. However, adamantiylation of methyl 4-(5-
thioxo-4,5-dihydro-1H-tetrazol-1-yl)benzoate (Ic) in
sulfuric acid afforded analogous products. The ratio of
monoadamantyl-substituted isomers IIc, IIIb, and IVb
Scheme 1.
S−
Ad
S
R
S
R
R
N
N
N
AdOH
H2SO4
+
N
N
N
N
N
N
H
+
N
N
N
In order to elucidate whether conjugation between
the aromatic substituent with the sulfur atom affects
the direction of adamantylation of 1-aryltetrazole-5-
thiones, the reaction of 1-ethyltetrazole-5-thione (Ib)
with adamantan-1-ol was studied. Compound Ib
readily reacted with adamantan-1-ol in concentrated
sukfuric acid to give mesoionic 3-(1-adamantyl)-1-
ethyltetrazolium-5-thiolate (IIb), small amounts of 5-
(1-adamantylsulfanyl)-1-ethyltetrazole (IIIa) and 4-(1-
adamantyl)-1-ethyltetrazole-5-thione (IVa), and 3-(1-
adamantyl)-5-(1-adamantylsulfanyl)-1-ethyltetrazolium
salt which was isolated as sulfate Va or perchlorate Vc
Ad
Ib, Ic
IIb, IIc
IIIа, IIIb
Ad
S
S
R
R
N
N
N
+
+
X−
N
N
N
Ad
+
N
N
Ad
Vа−Vd
IVа, IVb
Ib, IIb, IIIa–Va, R = Et, X = HSO4; Ic, IIc, IIIb–Vb, R =
4-(MeOCO)C6H4, X = HSO4; Vc, R = Et, X = ClO4; Vd,
R = 4-(MeOCO)C6H4, X = ClO4.
1
For communication XI, see [1].
2220

ADAMANTYLAZOLES: XII.
2221
was 82:14:4, and also tetrazolium salt Vb or Vd was
isolated.
1,3-Disubstituted tetrazolium-5-thiolates having alkyl
or aromatic groups are characterized by δC values
ranging from 173.0 to 173.9 ppm [1, 4–6, 13]. Deriva-
tives 1-R-tetrazole-5-thiones with a substituent on the
sulfur atom, including tetrazoles VIa and VIb
displayed C5 signals in the region δC 150.4–155.1 ppm
[1, 4, 11, 12, 14–18], while the C5 signals of 1,4-
disubstituted tetrazole-5-thiones are located at δC
162.5–164.7 ppm [4, 12, 14–17, 19]. There are no
published data for 1,2-disubstituted derivatives, and
their formation in the alkylation of 1-R-tetrazole-5-
thiones is hardly probable [2].
In the alkylation of compounds Ib and Ic with
excess adamantan-1-ol, the major products were
tetrazolium salts V. On heating in aqueous solution
sulfates Va and Vb underwent hydrolysis with
liberation of adamantan-1-ol and formation of mixtures
of compounds IIb, IIIb, and IVa, or IIc, IIIa, and
IVb, the S-adamantyl isomer (IIIa or IIIb) prevailing
(Scheme 2).
Scheme 2.
H2O
Va, Vb
IIb, IIc + IIIa, IIIb + IVa, IVb.
The chemical shifts of the endocyclic carbon atom
in compounds VIIa and VIIb and analogous 1,3,5-
trisubstituted tetrazolium salts range from δC 161.3 to
162.7 ppm [4, 6, 13], though the C5 signal of 3-(1-
adamantyl)-5-(1-adamantylsulfanyl)-1-phenyltetrazolium
perchlorate is located at δC 157.8 ppm [1]. The 13C
NMR spectra of the examined compounds are
consistent with published data, but the C5 signal in the
spectra of adamantyl derivatives is displaced upfield,
−AdOH
Taking into account published data on tetrazolium
salts [7, 8], we believed it reasonable to perform
adamantylation of 1-substituted 5-methylsulfanyltetra-
zoles VIa and VIb in sulfuric acid in order to confirm
the structure of compounds V. As a result, we isolated
1-R-3-(1-adamantyl)-5-methylsulfanyltetrazolium salts
VIIa and VIIb, respectively (Scheme 3). These data
indicate that the formation of 1,3,5-trisubstituted
tetrazolium salts in the adamantylation of 1-R-tetra-
zole-5-thiones is preferred, as in other reactions of 1,5-
disubstituted tetrazoles with alcohols in acid medium
[8].
O1
C9
O2
Scheme 3.
C8
C5
SMe
SMe
R
R
C6
N
N
AdOH
H2SO4
N
N
ClO4−
N
N
C7
+
N
C4
C3
N
Ad
VIIа, VIIb
R = Ph (a), Et (b).
C2
N1
VIа, VIb
S1
C1
C28
N2
The structure of salt Vd was proved by X-ray
analysis; its molecule is shown in Fig. 1. The position
of the adamantyl group in the other products was
determined on the basis of the 13C NMR spectra. The
chemical shift of C5 in the tetrazole ring strongly
depends on the substitution pattern and the nature of
the exocyclic heteroatom. NMR data for a wide series
of mesoionic compounds were reviewed in [9]. The
13C NMR spectra of the newly synthesized compounds
are collected in Table 1.
C24
C20
N3
C10
C22
N4
C25
C11
C23
C21
C22
C26
C18
C19
C14
C12
C13
C17
C16
C29
C15
In keeping with published data, the chemical shift
of the endocyclic carbon atom in 1-R-tetrazole-5-
thiones ranges from δC 162.9 to 164.2 ppm [4, 10–12].
Fig. 1. Structure of the molecule of 3-(1-adamantyl)-5-(1-
adamantylsulfanyl)-1-[4-(methoxycarbonyl)phenyl]tetrazolium
perchlorate (Vd) according to the X-ray diffraction data.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2222
LOGVINOV et al.
Table 1. 13C NMR spectra (δC, ppm) of compounds I–XI in DMSO-d6–CCl4 (4:1)
Comp. no.
Ib
С5
Substituent signals
163.60а
164.44b
172.74а
173.21а
149.26
151.19
161.27
161.70
156.22
157.96а
41.85, 13.15 (Et)
Ic
165.41 (CO2); 138.32, 130.66, 130.23, 123.36 (C6H4); 51.91 (Me)
IIb
66.88, 40.73, 34.99, 28.87 (Ad); 43.00, 12.89 (Et)
IIc
165.40 (CO2); 137.91, 130.76, 130.09, 125.13 (C6H4); 67.86, 40.71, 35.06, 28.96 (Ad); 52.68 (Me)
52.82, 42.99, 35.41, 29.70 (Ad); 42.66, 14.69 (Et)
IIIa
IIIb
IVa
IVb
Vc
165.26 (CO2); 137.02, 131.44, 130.71, 125.86 (C6H4); 53.81, 42.66, 35.38, 29.69 (Ad); 52.68 (Me)
63.46, 38.40, 35.38, 29.04 (Ad); 42.33, 12.90 (Et)
165.18 (CO2); 137.74, 130.55, 130.14, 124.89 (C6H4); 64.35, 38.45, 35.48, 29.21 (Ad); 52.41 (Me)
70.30, 56.58, 42.67, 40.79, 35.21, 34.91, 29.92, 29.01 (ди-Ad); 46.66, 12.75 (Et)
Vd
165.02 (CO2); 134.94, 133.41, 131.17, 126.53 (C6H4); 71.17, 57.51, 42.33, 40.90, 35.19, 34.84, 29.91,
29.07 (Ad); 52.95 (Me)
VIb
VIIa
VIIb
VIIIc
IXa
IXb
IXc
IXd
Xa
153.71
162.38
161.35
150.14а
158.84а
160.30
158.82а
158.69а
173.08
173.46
158.98
158.79
42.29, 13.99 (Et); 15.01 (Me)
132.92, 131.52, 130.52, 125.29 (Ph); 70.93, 40.90, 34.92, 29.07 (Ad); 15.89 (Me)
70.26, 40.88, 34.92, 29.02 (Ad); 46.46, 12.36 (Et); 15.65 (Me)
165.48 (CO2); 138.07, 130.66, 127.99, 118.26 (C6H4); 52.33 (Me)
134.23, 129.46, 128.16, 120.27 (Ph); 66.61, 40.44, 35.04, 28.76 (Ad)
65.65, 40.74, 35.35, 28.91 (Ad); 39.15, 13.63 (Et)
165.51 (CO2); 138.12, 130.74, 128.72, 119.63 (C6H4); 67.18, 40.53, 35.16, 28.91 (Ad); 52.49 (Me)
145.95, 139.32, 125.25, 120.15 (C6H4); 67.38, 40.46, 35.09, 28.84 (Ad)
134.27, 130.09, 129.09, 125.10 (Ph); 68.10, 28.13 (t-Bu)
67.45, 28.16 (t-Bu); 42.98, 13.01 (Et)
Xb
XIa
134.43, 129.42, 128.10, 120.17 (Ph); 67.18, 27.86 (t-Bu)
145.99, 139.42, 125.18, 120.14 (C6H4); 67.99, 27.81 (t-Bu)
XIb
a
In DMSO-d6. b In acetone-d6.
especially for compounds IIIa, IIIb, Vc, and Vd
having an adamantyl substituent on the sulfur atom.
adamantan-1-ol in concentrated sulfuric acid occurred
regioselectively at the N3 atom, and the products were
mesoionic 1-R-3-(1-adamantyl)tetrazolium-5-olates IXa–
IXd whose yield reached 81% (Scheme 4 ).
Alkylation of 1-R-tetrazol-5-ones in strong acids
was not studied previously. The alkylation in alkaline
medium generally involves the N4 atom, and the
corresponding O-alkyl derivatives are sometimes
formed only in small amounts [20–26]. The formation
of a mixture of 3- and 4-alkyl-substituted derivatives
was also reported [27], but mesoionic tetrazolium-5-
olates are commonly synthesized by other methods [3,
5, 6, 27–29].
Scheme 4.
O−
O
R
R
N
N
AdOH
H2SO4
N
N
N
N
+
N
N
H
Ad
IXа−IXd
VIIIа−VIIId
Unlike adamantylation of tetrazole-5-thiones,
reactions of 1-R-tetrazol-5-ones VIIIa–VIIId with
R = Ph (a), Et (b), 4-(MeOCO)C6H4 (c), 4-O2NC6H4 (d).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

ADAMANTYLAZOLES: XII.
2223
The structure of compound IXa was determined by
X-ray analysis (Fig. 2), some bond lengths and bond
angles in molecule IXa are given in Table 2, and Table 3
contains hydrogen bond parameters. The tetrazole ring
is planar: the mean-square deviation of atoms from the
ring plane is 0.0025 Å. The O1, C2, and C8 atoms
deviate from the tetrazole ring plane by –0.016(2),
0.067(2), and 0.085(2) Å, respectively; these devia-
tions are larger than those observed in structure IIa [1].
The dihedral angle between the tetrazole and phenyl
rings in molecule IXa is considerably smaller than in
IIa [11.6(1)° and 48.96(7)°, respectively] [1].
Presumably, mutual orientation of the heterocycle and
aromatic ring in structures IXa and IIa is determined
by steric requirements for intramolecular hydrogen
bonding (C7–H7···A, where A = O1 in IXa or S1 in
IIa). Flattening of the phenyltetrazolone fragment in
molecule IXa makes the intramolecular hydrogen bond
C3–H3···N2 stronger. Rotation of the tetrazole ring
about the adamantyl group is restricted as a result of
formation of intramolecular hydrogen bonds C14–
bond in 1,4-substituted tetrazolones (1.192 [30] and
1.174 Å [31]). The Cambridge Structural Database
[32] contain parameters of only one mesoionic 1,3-
substituted tetrazolone, 3-(2-hydroxyethyl)-1-methyl-
tetrazolium-5-olate [27]. The C–O bond length in the
latter (1.231 Å) is similar to that in molecule IXa, the
endocyclic bonds are leveled to a greater extent, and
the internal bond angles vary within 0.2–1.0°.
The X-ray diffraction data are consistent with the
13C NMR spectra. The chemical shifts of the endo-
cyclic carbon atom in compounds IXa–IXd fall into
the range typical of 1,3-disubstituted tetrazolium-5-
olates, i.e., δC 158.8–161.4 ppm [5, 6, 13, 27, 33, 34],
whereas known 1,4-disubstituted tetrazol-5-one deriva-
tives are characterized by δC values ranging from 145.5
to 150.9 ppm [11, 15–17, 27, 35, 36]; 1-R-tetrazol-5-
ones display C5 signal in the region δC 148.7–
152.0 ppm [10, 11, 35].
Thus, regardless of the substituent nature, ada-
mantylation of 1-R-tetrazole-5-thiones and 1-R-
tetrazol-5-ones in sulfuric acid involves mainly the N3
atom with formation of mesoionic compounds. It might
be presumed that the reaction direction is determined
by specific structure and properties of adamantyl
cation. Therefore, it was reasonable to elucidate
whether mesoionic tetrazole-5-thione and tetrazol-5-
one derivatives could be formed in reactions with a
different carbocation. The alkylation of tetrazoles with
alcohols giving rise to carbocations in strong acids has
been extensively studied [21, 37–44]. We performed
H
14B···N4 and C13–H13A···N4.
The bond lengths and bond angles in the tetrazole
ring of IXa approach the corresponding parameters of
molecule IIa. The largest differences in the geometry
of the tetrazole ring in IXa include extension of the
C1–N1 and C1–N4 bonds (by 0.025 and 0.012 Å,
respectively), increase of the N2N3N4 angle by 1°, and
decrease of the C1N1N2 angle by 0.9°. The C1–O1 bond
[1.225(2) Å] is slightly longer than the double C=O
C11
C12
C10
C16
C9
C17
C13
C8
N2
C4
C15
C14
C3
N3
N1
C5
C2
N4
C6
C7
C1
O1
Fig. 2. Structure of the molecule of 3-(1-adamantyl)-1-phenyltetrazolium-5-olate (IXa) according to the X-ray diffraction data.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2224
LOGVINOV et al.
Table 2. Selected bond lengths and bond angles in the molecule
of 3-(1-adamantyl)-1-phenyltetrazolium-5-olate (IXa)
Table 3. Hydrogen bond parameters in the crystalline
structure of 3-(1-adamantyl)-1-phenyltetrazolium-5-olate (IXa)
Bond
d, Å
Angle
N2N1C1
N2N1C2
C1N1C2
N3N2N1
N2N3N4
N2N3C8
N4N3C8
N3N4C1
O1C1N4
O1C1N1
N4C1N1
ω, deg
Symmetry
transformation
for the A atom
d(H···A), d(D···A),
∠DHA,
deg
D–H···A
O1–C1
N1–N2
N1–C1
N1–C2
N2–N3
N3–N4
N3–С8
N4–C1
1.2251(18)
1.3447(16)
1.4116(18)
1.4275(18)
1.2898(16)
1.3289(16)
1.4894(17)
1.358(2)
110.29(11)
119.18(11)
130.46(11)
102.97(11)
117.06(11)
121.34(11)
121.44(11)
104.51(11)
128.53(14)
126.30(14)
105.17(11)
Å
Å
С7–H7···O1
x, y, z
x, y, z
2.30(2) 2.968(2) 125.4(15)
2.43(2) 2.761(2) 99.1(13)
2.53(2) 2.855(2) 101.3(16)
2.78(2) 3.079(2) 96.8(13)
2.53(2) 3.508(2) 170.0(16)
2.69(2) 3.279(2) 117.6(14)
C3–H3···N2
C14–H14B···N4 x, y, z
C13–H13A···N4 x, y, z
С5–H5···O1
x, 1.5 – y, –0.5 + z
C14–H14A···O1 1 –x, –0.5+ y,
0.5 –z
study give rise to formation of several products which
occur in dynamic equilibrium with the initial com-
pounds and diadamantyl derivatives [1], but the most
stable are the corresponding mesoionic structures.
reactions of 1-R-tetrazole-5-thiones Ia and Ib and 1-R-
tetrazol-5-ones VIIIa and VIIId with tert-butyl
alcohol. In all cases, the major products were the
corresponding mesoionic 1-R-3-tert-butyltetrazolium-
5-thiolates Xa and Xb and 1-R-3-tert-butyltetrazo-
lium-5-olates XIa and XIb (Scheme 5).
EXPERIMENTAL
1
The H NMR spectra were recorded on a Bruker
WM-400 spectrometer from solutions in DMSO-d6.
The 13C NMR spectra were measured on a Bruker AC-
200 instrument. The elemental compositions were
determined on a Hewlett–Packard 185B analyzer. The
purity of the products was checked by TLC on Sorbfil
or Silufol UV-254 plates using chloroform,
chloroform–ethyl acetate (4:1), and chloroform–
acetone (1:1) as eluents; spots were visualized by UV
irradiation or treatment with iodine vapor. Silica gel L
100–160 μm or L 100–400 μm (Chemapol) was used
for column chromatography.
Scheme 5.
X−
X
R
R
N
N
t-BuOH
H2SO4
N
N
N
N
+
N
N
H
t-Bu
Xа, Xb, XIа, XIb
Iа, Ib, VIIIа, VIIId
Ia, Xa, R = Ph, X = S; Ib, Xb, R = Et, X = S; VIIIa, XIa,
R = Ph, X = O; VIIId, XIb, R = 4-O2NC6H4, X = O.
The X-ray diffraction data for compounds Vd and
IXa were deposited to the Cambridge Crystallographic
Data Centre (entry nos. CCDC 711823 and CCDC
693899, respectively).
We can conclude that the formation in the above
reactions of mesoionic compounds is determined by
specificity of acid-catalyzed alkylation process rather
than by the nature of substituent or alkylating agent. It
is important that reactions in a strong acid may involve
protonation of the initial tetrazole-5-thiones and
tetrazol-5-ones which are likely to be sufficiently basic
substrates [45]. Tetrazolium cations thus formed, as in
the reactions with 5-substituted tetrazoles [38, 40],
react with the carbocation as alkylating species.
Alkylation of azoles in strong acids is often reversible
[1, 40, 42–44, 46]. Presumably, the reactions under
Compound Vd. Colorless prisms, monoclinic
crystal system. Unit cell parameters: a = 12.1752(4),
b = 12.5376(4), c = 19.7629(7) Å; β = 90.824(2)°; V =
3016.45(17) Å3; dcalc = 1.332 g cm–3; µ(Mo) = 0.244 mm–1;
Z = 4; space group P21/c. Intensities of diffraction
reflections were measured on a Bruker SMART
APEX2 automatic diffractometer at room temperature
(MoKα irradiation, graphite monochro-mator) from a
0.50×0.48×0.30-mm single crystal. Total of 31424 re-
flection intensities were measured in the θ range from
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

ADAMANTYLAZOLES: XII.
2225
1.67 to 29.06°; 7794 reflections were independent
(Rint = 0.0338). The structure was solved by the direct
method. The positions of hydrogen atoms were
calculated on the basis of geometry considerations and
were refined using the riding model. Perchlorate ion is
disordered by two positions differing by rotation about
the Cl1–O3 bond. The structure was refined by the
least-squares procedures in anisotropic approximation
for thermal vibrations of non-hydrogen atoms, except
for the O7, O8, and O9 atoms in the perchlorate ion,
which were refined in isotropic approximation. The
final divergence factors were R1 = 0.1117, wR2 =
0.2941 for 4645 reflections with I > 2σ(I) and R1 =
0.1589, wR2 = 0.3260 for all independent reflections;
goodness of fit 1.055. The residual electron density
ranged from –0.617 to 0.892 e/Å3.
1-Ethy-5-methylsulfanyl-1H-tetrazole (VIb). bp
1
93°C (1 mm). H NMR spectrum, δ, ppm: 4.26 q (2H,
CH2, 3J = 6.9 Hz), 2.75 s (3H, SCH3), 1.43 t (3H, CH3,
3J = 6.9 Hz).
1-Ethyl-4,5-dihydro-1H-tetrazol-5-one (VIIIb).
After hydrolysis, the reaction mixture was diluted with
water, washed with chloroform, acidified with
hydrochloric acid to pH 1, and extracted with me-
thylene chloride. The extract was dried over sodium
sulfate, filtered through a layer of activated charcoal,
1
and evaporated. According to the H NMR data, the
product contained ~15% of tetrazole-5-thione Ib as
1
impurity. H NMR spectrum, δ, ppm: 14.13 br.s (1H,
3
NH), 3.87 q (2H, CH2, J = 6.9 Hz), 1.33 t (3H, CH3,
3J = 6.9 Hz).
Methyl 4-(5-thioxo-4,5-dihydro-1H-tetrazol-1-yl)-
benzoate (Ic). A mixture of 0.0225 mol of 4-(5-thioxo-
4,5-dihydro-1H-tetrazol-1-yl)benzoic acid and 50 ml
of methanol was heated for 2 h under reflux with
stirring while passing gaseous hydrogen chloride. The
mixture was diluted with water, and the precipitate was
filtered off, washed with water, and added to a solution
of sodium carbonate (pH 10). The solution was filtered
and acidified with hydrochloric acid to pH 1, and the
precipitate was filtered off, washed with water, and
recrystallized. Yield 2.91 g (55%), mp 148°C
(decomp.; from propan-2-ol–water, 1:1). 1H NMR
spectrum, δ, ppm: 8.11 s (4H, C6H4), 3.88 s (3H, CH3).
Found, %: C 45.72; H 3.80; N 23.74. C9H8N4O2S.
Calculated, %: C 45.76; H 3.41; N 23.71.
Compound IXa. Colorless prisms, monoclinic
crystal system. Unit cell parameters: a = 10.3122(15),
b = 12.595(5), c = 11.931(3) Å; β = 104.839(16)°; V =
1498.0(8) Å3; dcalc = 1.314 g/cm3; µ(Cu) = 0.678 mm–1;
Z = 4; space group P21/c. The set of experimental
reflection intensities was acquired at room temperature
on a CAD-4 automatic diffractometer (CuKα irradiation,
graphite monochromator) from a 0.90 × 0.66 × 0.30-mm
single crystal. Total of 4031 reflection intensities were
measured in the θ range from 4.44° to 69.93°; 2763 re-
flections were independent (Rint = 0.0484). The
structure was solved by the direct method. Hydrogen
atoms were localized by Fourier difference syntheses
of electron density. The structure was refined by the
least-squares procedures in anisotropic approximation
for thermal vibrations of non-hydrogen atoms and in
isotropic approximation for hydrogen atoms with
account taken of secondary extinction [c = 0.044(2)].
The final divergence factors were R1 = 0.0458, wR2 =
0.1254 for 2607 reflections with I > 2σ(I) and R1 =
0.0479, wR2 = 0.1273 for all independent reflections;
goodness of fit 1.092. The residual electron density Δρ
ranged from –0.242 to 0.165 e Å–3. No correction for
absorption was introduced. All calculations were per-
formed using SHELX97 software [47].
Methyl
4-(5-oxo-4,5-dihydro-1H-tetrazol-1-yl)
benzoate (VIIIc). A mixture of 0.0146 mol of 4-(5-
oxo-4,5-dihydro-1H-tetrazol-1-yl)benzoic acid (prepared
by analogy with [50]), 60 ml of methanol, and 30 ml of
acetone was heated for 10 h under reflux with stirring
while passing gaseous hydrogen chloride. The product
was isolated as described above for compound Ic.
Yield 2.25 g (70%), mp 219°C (decomp.; from ethyl
1
acetate). H NMR spectrum, δ, ppm: 14.82 br.s (1H,
NH), 8.02 d (2H, C6H4, 3J = 8.9 Hz), 7.97 d (2H, C6H4,
3J = 8.9 Hz,), 3.82 s (3H, CH3). Found, %: C 48.89; H
4.03; N 25.76. C9H8N4O3. Calculated, %: C 49.09; H
3.66; N 25.44.
Initial 1-ethyltetrazole-5-thione (Ib) was syn-
thesized from ethyl isothiocyanate according to the
procedure reported in [48]. Compounds VIa, VIIIa,
and VIIId were prepared as described in [49, 50], and
derivatives VIb and VIIIb were obtained in a similar
way.
Reaction of 1-R-tetrazole-5-thiones Ib and Ic with
adamantan-1-ol (general procedure). A solution of
7.7 mmol of adamantan-1-ol and 7.7 mmol of
tetrazolethione Ib or Ic in 20 ml of 94% sulfuric acid
was heated for 2 h at room temperature. The mixture
was poured onto ice and diluted with water to a
1-Ethyl-4,5-dihydro-1H-tetrazole-5-thione (Ib).
1
bp 109°C (1 mm). H NMR spectrum, δ, ppm: 4.23 q
(2H, CH2, 3J = 6.9 Hz), 1.39 t (3H, CH3, 3J = 6.9 Hz).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2226
LOGVINOV et al.
volume of 400 ml. The precipitate was filtered off,
washed with water, and dried in air. The product
mixture was analyzed by thin-layer chromatography
evaporated to dryness; the residue was tetrazolium
sulfate Va or Vb. To isolate perchlorates Vc and Vd, a
solution of perchloric acid was added to the filtrate,
and the precipitate was filtered off, washed with water,
and dried (yield 89 and 76%, respectively).
1
and H NMR spectroscopy. Compounds IIb and IIc
were isolated by recrystallization. A solution of
perchloric acid was added to the aqueous filtrate, and
the precipitate was filtered off, washed with water, and
dried in air to isolate tetrazolium perchlorates Vc and
Vd.
Hydrolysis of compounds Va and Vb (general
procedure). Salt Va or Vb isolated as described above
was dissolved in 100 ml of water, and the solution was
heated for 1 h at the boiling point. The mixture was
cooled and extracted with methylene chloride, and the
extract was dried over sodium sulfate, and evaporated
3-(1-Adamantyl)-1-ethyltetrazolium-5-thiolate (IIb).
Yield 19%, mp 144–146°C (from hexane–propan-2-ol,
1
1
10:1). H NMR spectrum, δ, ppm: 4.32 q (2H, CH2,
to dryness. According to the TLC and H NMR data,
3J = 6.9 Hz), 2.23 s (9H, Ad), 1.75 s (6H, Ad), 1.42 t
(3H, CH3, 3J = 6.9 Hz). Found, %: C 59.05; H 6.64; N
21.35. C13H20N4S. Calculated, %: C 59.09; H 7.57; N
21.21.
the product contained adamantan-1-ol and isomers IIb,
IIIa, and IVa at a ratio of 23:69:8 or isomers IIc,
IIIb, and IVb at a ratio of 10:83:7. Individual isomers
were isolated from the residue by column
chromatography on silica gel using chloroform or
chloroform–hexane (1:1) as eluent.
3-(1-Adamantyl)-1-[4-(methoxycarbonyl)phenyl]-
tetrazolium-5-thiolate (IIc). Yield 25%, mp 157–159°C
1
(from propan-2-ol). H NMR spectrum, δ, ppm: 8.16 s
5-(1-Adamantylsulfanyl)-1-ethyl-1H-tetrazole (IIIa).
(4H, C6H4), 3.89 s (3H, CH3), 2.29 s (6H, Ad), 2.24 s
(3H, Ad), 1.73 s (6H, Ad). Found, %: C 61.43; H 5.76;
N 14.90. C19H22N4O2S. Calculated, %: C 61.62; H
5.94; N 15.13.
Yield 34% (calculated on the initial tetrazolethione),
1
mp 65–67°C (from hexane). H NMR spectrum, δ,
3
ppm: 4.37 q (2H, CH2, J = 6.9 Hz), 2.05 s (3H, Ad),
2.01 s (6H, Ad), 1.66 s (6H, Ad), 1.42 t (3H, CH3, 3J =
6.9 Hz). Found, %: C 59.36; H 7.86; N 21.48.
C13H20N4S. Calculated, %: C 59.09; H 7.57; N 21.21.
3-(1-Adamantyl)-5-(1-adamantylsulfanyl)-1-ethyl-
tetra-zolium perchlorate (Vc). Yield 26%, mp 170–
172°C (from ethanol). 1H NMR spectrum, δ, ppm: 4.53
Methylovyi 4-[5-(1-adamantylsulfanyl)-1H-tetra-
zol-1-yl]benzoate (IIIb). Yield 56% (calculated on the
initial tetrazolethione), mp 150–152°C (from hexane–
3
q (2H, CH2, J = 6.9 Hz), 2.35 s (9H, Ad), 2.15 s (9H,
Ad), 1.81 s (6H, Ad), 1.73 s (6H, Ad), 1.57 t (3H, CH3,
3J = 6.9 Hz). Found, %: C 55.97; H 7.07; N 11.61.
C23H35N4S·ClO4. Calculated, %: C 55.37; H 7.02; N
11.23.
1
propan-2-ol, 1:1). H NMR spectrum, δ, ppm: 8.19 d
(2H, C6H4, 3J = 8.9 Hz), 7.75 d (2H, C6H4, 3J = 8.9 Hz),
3.92 s (3H, CH3), 2.07 s (9H, Ad), 1.69 s (6H, Ad).
Found, %: C 61.65; H 6.59; N 15.16. C19H22N4O2S.
Calculated, %: C 61.62; H 5.94; N 15.13.
3-(1-Adamantyl)-5-(1-adamantylsulfanyl)-1-[4-(me-
thoxycarbonyl)phenyl]tetrazolium perchlorate (Vd).
1
Yield 17%, mp 183°C (decomp.; from ethanol). H
1-(1-Adamantyl)-4-ethyl-4,5-dihydro-1H-tetra-
zole-5-thione (IVa). Yield 4% (calculated on the initial
NMR spectrum, δ, ppm: 8.30 d (2H, C6H4, 3J = 8.9 Hz),
7.93 d (2H, C6H4, 3J = 8.9 Hz), 3.95 s (3H, CH3), 2.43
s (6H, Ad), 2.38 s (3H, Ad), 2.17 s (6H, Ad), 2.15 s
(3H, Ad), 1.84 s (6H, Ad), 1.74 s (6H, Ad). Found, %:
C 57.07; H 5.40; N 9.59. C29H37N4O2S·ClO4. Cal-
culated, %: C 57.57; H 6.12; N 9.26.
1
tetrazolethione), mp 100–101°C (from hexane). H
NMR spectrum, δ, ppm: 4.25 q (2H, CH2, 3J = 6.9 Hz),
2.51 s (6H, Ad), 2.18 s (3H, Ad), 1.70 s (6H, Ad), 1.36
3
t (3H, CH3, J = 6.9 Hz). Found, %: C 58.80; H 7.78;
N 20.92. C13H20N4S. Calculated, %: C 59.09; H 7.57;
N 21.21.
Reaction of 1-R-tetrazole-5-thiones Ib and Ic
with excess adamantan-1-ol (general procedure). A
solution of 15.4 mmol of adamantan-1-ol and
7.7 mmol of tetrazolethione Ib and Ic in 25 ml of 94%
sulfuric acid was stirred for 3 h at room temperature.
The mixture was poured onto ice, diluted with water to
a volume of 500 ml, and filtered. The filtrate was
extracted with methylene chloride (3×50 ml), and the
extracts were combined, dried over sodium sulfate, and
Methyl 4-[4-(1-adamantyl)-5-thioxo-4,5-dihydro-
1H-tetrazol-1-yl]benzoate (IVb). Yield 5% (cal-
culated on the initial tetrazolethione), mp 178–181°C
(from hexane). 1H NMR spectrum, δ, ppm: 8.17 d (2H,
3
3
C6H4, J = 8.5 Hz), 8.03 d (2H, C6H4, J = 8.5 Hz),
3.91 s (3H, CH3), 2.62 s (6H, Ad), 2.26 s (3H, Ad),
1.78 s (6H, Ad). Found, %: C 61.11; H 5.53; N 14.72.
C19H22N4O2S. Calculated, %: C 61.62; H 5.94; N 15.13.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

ADAMANTYLAZOLES: XII.
2227
The reaction of 1-R-5-methylsulfanyltetrazoles
VIa and VIb with adamantan-1-ol was carried out as
described above for the adamantylation of tetra-
zolethiones I, and compounds VIIa and VIIb were
isolated as described above for tetrazolium salts Vc
and Vd.
ppm: 8.13 s (4H, C6H4), 3.87 s (3H, CH3), 2.25 s (9H,
Ad), 1.73 s (6H, Ad). Found, %: C 64.59; H 7.06; N
16.20. C19H22N4O3. Calculated, %: C 64.41; H 6.21; N
15.82.
3-(1-Adamantyl)-1-(4-nitrophenyl)tetrazolium-5-
olate (IXd). Yield 73%, mp 212–214°C (from
1
3-(1-Adamantyl)-5-methylsulfanyl-1-phenyltetra-
zolium perchlorate (VIIa). Yield 78%, mp 171°C
(decomp., from propan-2-ol–chloroform, 10:1). 1H
NMR spectrum, δ, ppm: 7.80–7.79 m (5H, C6H5), 2.87
s (3H, CH3), 2.40 s (6H, Ad), 2.33 s (3H, Ad), 1.79 s
(6H, Ad). Found, %: C 50.81; H 5.73; N 13.55.
C18H23N4S·ClO4. Calculated, %: C 50.64; H 5.39; N
13.13.
ethanol–acetone, 3:1). H NMR spectrum, δ, ppm:
8.41 d (2H, C6H4, 3J = 8.9 Hz), 8.24 d (2H, C6H4, 3J =
8.9 Hz), 2.25 s (9H, Ad), 1.73 s (6H, Ad). Found, %: C
60.33; H 4.76; N 21.03. C17H19N5O3. Calculated, %: C
59.82; H 5.57; N 20.53.
Reaction of 1-R-tetrazole-5-thiones Ia and Ib
with tert-butyl alcohol (general procedure). tert-Butyl
alcohol, 3.5 mmol, was added dropwise to a solution of
3.1 mmol of compound Ia and Ib in 5 ml of 94%
sulfuric acid. The mixture was stirred for 1.5 h at room
temperature, poured onto ice, diluted with water to a
volume of 100 ml, and extracted with methylene
chloride (4×25 ml). The extracts were washed with a
dilute solution of sodium carbonate and water, dried
over sodium sulfate, and evaporated to dryness, and
the residue was purified by recrystallization to isolate
compounds Xa and Xb.
3-(1-Adamantyl)-1-ethyl-5-methylsulfanyltetra-
zolium perchlorate (VIIb). Yield 52%, mp 213°C
1
(decomp., from propan-2-ol). H NMR spectrum, δ,
ppm: 4.46 q (2H, CH2, 3J = 6.9 Hz), 2.85 s (3H, CH3),
2.32 s (9H, Ad), 1.78 s (6H, Ad), 1.55 t (3H, CH3, 3J =
6.9 Hz). Found, %: C 43.98; H 6.31; N 14.97.
C14H23N4S·ClO4. Calculated, %: C 44.38; H 6.08; N
14.79.
The reaction of 1-R-tetrazol-5-ones VIIIa–VIIId
with adamantan-1-ol was carried out as described
above for the adamantylation of tetrazolethiones I, and
compounds IXa, IXc, and IXd were isolated as
described above for mesoionic derivatives II.
3-tert-Butyl-1-phenyltetrazolium-5-thiolate (Xa).
1
Yield 15%, mp 168–170°C (from propan-2-ol). H
NMR spectrum, δ, ppm: 7.93–7.58 m (5H, C6H5), 1.74 s
(9H, t-Bu). Found, %: C 56.55; H 6.05; N 23.73.
C11H14N4S. Calculated, %: C 56.41; H 5.98; N 23.93.
3-(1-Adamantyl)-1-phenyltetrazolium-5-olate (IXa).
Yield 74%, mp 179–181°C (from propan-2-ol–water,
1
3-tert-Butyl-1-ethyltetrazolium-5-thiolate (Xb).
1:1). H NMR spectrum, δ, ppm: 7.93–7.41 m (5H,
Yield 21%, mp 113–115°C (from hexane–propan-2-ol,
C6H5), 2.24 s (9H, Ad), 1.72 s (6H, Ad). Found, %: C
69.29; H 7.27; N 19.43. C17H20N4O. Calculated, %: C
68.92; H 6.76; N 18.92.
1
10:1). H NMR spectrum, δ, ppm: 4.33 q (2H, CH2,
3
3J = 6.9 Hz), 1.68 s (9H, t-Bu), 1.42 t (3H, CH3, J =
6.9 Hz). Found, %: C 44.81; H 7.84; N 29.86.
C7H14N4S. Calculated, %: C 45.16; H 7.53; N 30.11.
3-(1-Adamantyl)-1-ethyltetrazolium-5-olate (IXb).
After dilution with water, the resulting solution was
extracted with methylene chloride (4×40 ml). The
extracts were combined, dried over sodium sulfate, and
evaporated to dryness. The product was isolated from
the residue by column chromatography on silica gel
using chloroform–ethyl acetate (4:1) as eluent. Yield
71%, mp 110–112°C (from hexane–carbon tetra-
The reaction of 1-R-tetrazol-5-ones VIIIa and
VIIId with tert-butyl alcohol was carried out in a
similar way; the products were compounds XIa and
XIb.
3-tert-Butyl-1-phenyltetrazolium-5-olate (XIa).
Yield 52%, mp 118–120°C (from hexane–propan-2-ol,
1
1
chloride, 10:1). H NMR spectrum, δ, ppm: 3.97 q
10:1). H NMR spectrum, δ, ppm: 7.94–7.42 m (5H,
3
(2H, CH2, J = 6.9 Hz), 2.23 s (3H, Ad), 2.17 s (6H,
C6H5), 1.69 s (9H, t-Bu). Found, %: C 60.01; H 6.82;
N 25.39. C11H14N4O. Calculated, %: C 60.55; H 6.42;
N 25.69.
3
Ad), 1.74 s (6H, Ad), 1.35 t (3H, CH3, J = 6.9 Hz).
Found, %: C 63.24; H 7.99; N 22.65. C13H20N4O.
Calculated, %: C 62.90; H 8.06; N 22.58.
3-tert-Butyl-1-(4-nitrophenyl)tetrazolium-5-olate
(XIb). Yield 41%, mp 149–151°C (from propan-2-ol).
3-(1-Adamantyl)-1-[4-(methoxycarbonyl)phenyl]-
3
1H NMR spectrum, δ, ppm: 8.39 d (2H, C6H4, J =
tetrazolium-5-olate (IXc). Yield 81%, mp 159–161°C
1
3
(from propan-2-ol–water, 1:1). H NMR spectrum, δ,
8.9 Hz), 8.26 d (2H, C6H4, J = 8.9 Hz), 1.71 s (9H, t-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

2228
LOGVINOV et al.
19. L’abbé, G., Verhelst, G., and Toppet, S., J. Org. Chem.,
Bu). Found, %: C 50.57; H 5.33; N 26.97. C11H13N5O3.
Calculated, %: C 50.19; H 4.94; N 26.61.
1977, vol. 42, no. 7, p. 1159.
20. Hattori, K., Lieber, E., and Horwitz, J.P., J. Am. Chem.
Soc., 1956, vol. 78, no. 2, p. 411.
ACKNOWLEDGMENTS
21. Quast, H. and Bieber, L., Chem. Ber., 1981, vol. 114,
no. 10, p. 3253.
22. Quast, H. and Nahr, U., Chem. Ber., 1983, vol. 116,
no. 10, p. 3427.
This study was performed under financial support by
the Government of St. Petersburg.
23. Quast, H. and Nahr, U., Chem. Ber., 1984, vol. 117,
no. 8, p. 2761.
REFERENCES
24. Janssens, F., Torremans, J., and Janssen, P.A.J., J. Med.
Chem., 1986, vol. 29, no. 11, p. 2290.
25. Kitazaki, T., Tamura, N., Tasaka, A., Matsushita, Y.,
Hayashi, R., Okonogi, K., and Itoh, K., Chem. Pharm.
Bull., 1996, vol. 44, no. 2, p. 314.
1. Logvinov, A.V., Saraev, V.V., Polyakova, I.N.,
Strelenko, Yu.A., and Golod, E.L., Russ. J. Gen. Chem.,
2007, vol. 77, no. 12, p. 2186.
2. Koldobskii, G.I., Hrabalek, A., and Esikov, K.A., Russ.
J. Org. Chem., 2004, vol. 40, no. 4, p. 447.
26. Poplavskaya, Yu.V., Alam, L.V., and Koldobskii, G.I.,
Russ. J. Org. Chem., 2000, vol. 36, no. 12, p. 1793.
27. Awadallah, A., Rademacher, P., and Boese, R., J. Prakt.
Chem. Chem.-Zeitung., 1995, vol. 337, no. 1, p. 636.
28. Ollis, W.D. and Ramsden, C.A., Adv. Heterocycl.
Chem., 1976, vol. 19, p. 1.
29. Butler, R.N., Adv. Heterocycl. Chem., 1977, vol. 21,
p. 323.
30. Kudzma, L.V., Severnak, S.A., Benvenga, M.J.,
Ezel, E.F., Ossipov, M.H., Knight, V.V., Rudo, F.G.,
Spencer, H.K., and Spaulding, T.C., J. Med. Chem.,
1989, vol. 32, no. 12, p. 2534.
31. Durant, F., Michel, A., Lebrun, B., and Evrard, G., Bull.
Soc. Chim. Belg., 1987, vol. 96, no. 4, p. 331.
32. Cambridge Structural Database. Version 1.10,
Cambridge: Cambridge Crystallographic Data Centre,
2007.
3. Newton, C.G. and Ramsden, C.A., Tetrahedron, 1982,
vol. 38, no. 20, p. 2965.
4. Bartels-Keith, J.R., Burgess, M.T., and Stevenson, J.M.,
J. Org. Chem., 1977, vol. 42, no. 23, p. 3725.
5. Araki, S., Wanibe, Y., Uno, F., Morikawa, A.,
Yamamoto, K., Chiba, K., and Butsugan, Y., Chem.
Ber., 1993, vol. 126, no. 5, p. 1149.
6. Bocian, W., Jazwinski, J., Kozminski, W., Stefaniak, L.,
and Webb, G.A., J. Chem. Soc. Perkin Trans. 2, 1994,
no. 6, p. 1327.
7. Zhivich, A.B., Koldobskii, G.I., and Ostrovskii, V.A.,
Khim. Geterotsikl. Soedin., 1990, no. 12, p. 1587.
8. Voitekhovich, S.V., Gaponik, P.N., and Ivashkevich, O.A.,
Usp. Khim., 2002, vol. 71, no. 9, p. 819.
9. Stefaniak, L. and Jazwinski, J., Khim. Geterotsikl.
Soedin., 1995, no. 9, p. 1180.
10. Könnecke, A., Lippmann, E., and Kleinpeter, E., Z.
Chem., 1975, vol. 15, no. 10, p. 402.
33. Araki, S., Mizuya, J., and Butsugan, Y., J. Chem. Soc.
Perkin Trans. 1, 1985, p. 2439.
34. Jazwinski, J., Rozwadowski, Z., Magiera, D., and
Duddeck, H., Magn. Reson. Chem., 2003, vol. 41, no. 5,
p. 315.
11. Bojarska-Olejnic, E., Stefaniak, L., Witanowski, M., and
Webb, G.A., Bull. Pol. Acad. Sci. Chem., 1986, vol. 34,
nos. 7, 8, p. 295.
35. Tsuge, O., Urano, S., and Oe, K., J. Org. Chem., 1980,
vol. 45, no. 25, p. 5130.
36. Haines, D.R., Leonard, N.J., and Wiemer, D.F., J. Org.
Chem., 1982, vol. 47, no. 3, p. 474.
37. Shirobokov, I.Yu., Sachivko, A.V., Tverdokhlebov, V.P.,
Ostrovskii, V.A., Tselinskii, I.V., and Koldobskii, G.I.,
Zh. Org. Khim., 1986, vol. 22, no. 8, p. 1763.
38. Koren’, A.O. and Gaponik, P.N., Khim. Geterotsikl.
Soedin., 1990, no. 12, p. 1643.
39. Gaponik, P.N., Grigor’ev, Yu.V., Andreeva, T.N., and
Maruda, I.I., Khim. Geterotsikl. Soedin., 1995, no. 7,
p. 915.
40. Saraev, V.V. and Golod, E.L., Russ. J. Org. Chem.,
1997, vol. 33, no. 4, p. 571.
41. Gaponik, P.N., Voitekhovich, S.V., Ivashkevich, O.A.,
Lyakhov, A.S., and Govorova, A.A., Khim. Geterotsikl.
Soedin., 1998, no. 5, p. 657.
12. Narisada, M., Terui, Y., Watanabe, F., Ohtani, M., and
Miyazaki, H., J. Org. Chem., 1985, vol. 50, no. 15,
p. 2794.
13. Bocian, W., Jazwinski, J., Kozminski, W., Stefaniak, L.,
and Webb, G.A., Magn. Reson. Chem., 1994, vol. 32,
no. 5, p. 284.
14. L’abbé, G., Vermeulen, G., Flémal, J., and Toppet, S.,
J. Org. Chem., 1976, vol. 41, no. 10, p. 1875.
15. Quast, H. and Nahr, U., Chem. Ber., 1985, vol. 118,
no. 2, p. 526.
16. L’abbé, G., Toppet, S., Verhelst, G., and Martens, C.,
J. Org. Chem., 1974, vol. 39, no. 25, p. 3770.
17. Tochtermann, W., Gustmann, H., and Wolff, C., Chem.
Ber., 1978, vol. 111, no. 2, p. 566.
18. Hrabalek, A., Kunes, J., Pour, M., and Waisser, K., Russ.
J. Org. Chem., 2000, vol. 36, no. 5, p. 761.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009

ADAMANTYLAZOLES: XII.
2229
42. Gaponik, P.N. and Voitekhovich, S.V., Russ. J. Org.
Chem., 1998, vol. 34, no. 5, p. 746.
46. Amandurdyeva, A.D., Saraev, V.V., Polyakova, I.N., and
Golod, E.L., Russ. J. Gen. Chem., 2005, vol. 75, no. 9,
p. 1475.
47. Sheldrick, G.M., SHELXS97 and SHELXL97. Program
for the Solution and Refinement of Crystal Structures,
Göttingen, Germany: Univ. of Göttingen, 1997.
43. Gaponik, P.N., Voitekhovich, S.V., Maruda, I.I., Ku-
lak, A.A., and Ivashkevich, O.A., Pol. J. Chem., 1998,
vol. 72, no. 10, p. 2247.
44. Voitekhovich, S.V., Gaponik, P.N., Lyakhov, A.S., and
Ivashkevich, O.A., Khim. Geterotsikl. Soedin., 2001,
no. 8, p. 1035.
48. Lieber, E. and Ramachandran, J., Can. J. Chem., 1959,
vol. 37, no. 1, p. 101.
49. Gol’tsberg, M.A. and Koldobskii, G.I., Russ. J. Org.
Chem., 1996, vol. 32, no. 8, p. 1194.
50. Koreneva, A.P. and Koldobskii, G.I., Russ. J. Org.
Chem., 1999, vol. 35, no. 10, p. 1511.
45. Poplavskaya, Yu.V., Trifonov, R.E., Shcherbinin, M.B.,
and Koldobskii, G.I., Russ. J. Org. Chem., 2000, vol. 36,
no. 12, p. 1788.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 10 2009