Cyclization of nitriles: LIX. Synthesis and properties of 1-(2-thienyl)-4-cyano-5,6,7,8-tetrahydro-3(2H)-isoquinolinethione derivatives. Molecular and crystal structure of 3-isobutylsulfanyl-1-(2-thienyl)-4-cyano-5,6,7,8-tetrahydroisoquinoline

Article abstract of DOI:10.1023/A:1022522420258

By condensation of 2-(2-thenoyl)-1-cyclohexanone with cyanothioacetamide a new compound of a series of chalcogen-containing isoquinolines with a thiophene fragment in its structure was prepared. It was demonstrated that alkylation of the compound with haloalkanes and their derivatives, in particular with those having electron-withdrawing substituents furnished 3-alkylthio-4-cyano-5,6,7,8-tetrahydroisoquinolines. Some of the latter underwent cyclization into 3-amino-2-R-5-(2-thienyl)-6,7,8,9-tetrahydrothieno[2,3-c]-isoquinoline.

Full text of DOI:10.1023/A:1022522420258

Russian Journal of Organic Chemistry, Vol. 38, No. 11, 2002, pp. 1661 1665. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 11, 2002,
pp. 1718 1722.
Original Russian Text Copyright
2002 by Lozinskii, Chernega, Shelyakin.
Cyclization of Nitriles: LIX.* Synthesis and Properties
of 1-(2-Thienyl)-4-cyano-5,6,7,8-tetrahydro-3(2H)-
isoquinolinethione Derivatives. Molecular and Crystal Structure
of 3-Isobutylsulfanyl-1-(2-thienyl)-4-cyano-5,6,7,8-
tetrahydroisoquinoline
M. O. Lozinskii, A. N. Chernega, V. V. Shelyakin
Institute of Organic Chemistry, National Academy of Sciences of the Ukraine, Kiev, 02094 Ukraine
Received December 7, 2001
Abstract By condensation of 2-(2-thenoyl)-1-cyclohexanone with cyanothioacetamide a new compound of a
series of chalcogen-containing isoquinolines with a thiophene fragment in its structure was prepared. It was
demonstrated that alkylation of the compound with haloalkanes and their derivatives, in particular with those
having electron-withdrawing substituents furnished 3-alkylthio-4-cyano-5,6,7,8-tetrahydroisoquinolines.
Some of the latter underwent cyclization into 3-amino-2-R-5-(2-thienyl)-6,7,8,9-tetrahydrothieno[2,3-c]-
isoquinoline.
The structural fragment of isoquinoline and of its
partially hydrogenated analogs are found in the
molecules of many biologically active compounds,
among them alkaloids and azoanalogs of steroids;
some derivatives of this class show cardiotonic effect
[2 4]. As show published sources, derivatives of
cyanoacetic acids can serve convenient synthons for
building up the isoquinoline skeleton [5, 6]. It was
noted that the heterocyclyzation depends on a number
of factors, for instance, on the structure of the
original 1,3-diketone and of CH-acid component, on
the nature of the catalyst and solvent [6, 7]. Thus the
reaction of 2-acetylcyclohexanone with cyanoacet-
amide catalyzed with pyridine afforded a mixture of
isoquinolines [8]. The condensation of cyanothioacet-
amide with 2-thenoylacetylacetone also provided a
mixture of isomeric pyridines [9]. The cyclization of
cyanothioacetamide with enamines of 2-acetylcyclo-
hexane series proceeded regioselectively giving rise
exclusively to a single isoquinoline isomer [10 12].
The reaction of heterocyclic cycloalkane derivatives
with an exocyclic fragment of 1,3-dicarbonyl com-
pound (in particular containing a thiophene moiety)
with cyanothioacetamide was not investigated [6].
3-thione (III). The formation of isoquinoline III is
caused apparently, firstly, by steric factor (axial
position of carbonyl group in position 1 of the initial
reagent IA), and secondly, the thiophene fragment
introduced into compound I stabilizes the enol form
of the carbonyl attached to the heterocycle and there-
We showed that the condensation of 2-(2-thenoyl)-
1-cyclohexanone (I) with cyanothioacetamide (II) in
the presence of triethylamine resulted exclusively in
1-(2-thienyl)-4-cyano-5,6,7,8-tetrahydroisoquinoline-
General view of compoundVa molecule. Main bond lengths
( ) and bond angles (deg): S1 C5 1.758(3), S1 C15
1.791(3), N1 C1, N1 C5 1.322(4), C1 C2 1.408(4), C2
C3 1.395(4), C3 C4 1.389(4), C4 C5 1.395(4), C5S1C15
104.18(14).
*
For communication LVIII see [1].
1070-4280/02/3811-1661$27.00 2002 MAIK Nauka/Interperiodica

1662
LOZINSKII et al.
fore leads to elongation of the conjugation chain. We
believe that the formation of isoquinoline III under-
lies a cascade reaction of nucleophilic addition of
cyanothioacetamide to the carbonyl group of cyclo-
hexanone; in the course of reaction the cyanothio-
acetamide plays the role of dinucleophile. The sub-
sequent attack of the amino group from thioamide II
on the second carbonyl linked to the heterocyclic
fragment results in formation of the isoquinoline
skeleton of compound III. Like the substituted
3-cyano-2(H)-pyridinethiones [5] and 3-cyano-2(1H)-
quinolinethiones [7, 12] compound III easily under-
goes alkylation with various haloalkanes and their
derivatives IVa n in dimethylformamide in the
presence of KOH. Therewith were isolated and char-
acterized derivatives of 3-alkylthio-4-cyano-5,6,7,8-
tetrahydroisoquinoline Va n (Tables 1, 2).
ture of compounds Va n, VIn was confirmed by
spectral data (Table 2). However the data of IR and
1H NMR spectroscopy alone cannot ensure the choice
of one of two alternative structures originating either
from thione III or from IIIA.
To establish the structure of this class derivatives
we carried out X-ray diffraction analysis on a single
crystal of 3-isobutylthio-1-(2-thienyl)-4-cyano-5,6,7,8-
tetrahydroisoquinoline (Va). The general view of
molecule Va and its principal geometrical parameters
are given on a figure. The central six-membered
heterocycle N1C1 5 is planar: the deviation of atoms
from the root-mean-square plane does no exceed
0.019 . The five-membered ring S1C11 14 is virtual-
ly coplanar with that plane (the corresponding
dihedral angle is only 3.7 ). The cyclohexene ring
6 9
C2,3,
has common for analogous systems [13]
In the presence of excess alkali compound Vn
undergoes cyclization giving in high yield a derivative
of 1-aminothieno[2,3-c]isoquinoline VIn. The struc-
conformation of a distorted chair: the twist angle
(pceudotorsional angle between the bonds C2 C3 and
C7 C8) amounts to 31.5 ,
IV, V, R = CH(CH3)2 (a), 3,4-Cl2C6H3 (b), 4-ClC6H4 (c), C6H5 (d), 6-Cl-3,4-CH2OCH2C6H2 (e), 2,4-Cl2C6H3 (f),
2-ClC6H4 (g), 4-ClC6H4CONH (h), CH=CH2 (i), 2-CH3OC6H4CONH (j), 2-FC6H4CONH (k), 2-CH3O-5-ClC6H3
(l), 4-ClC6H4CO (m), 2,4-Cl2C6H3CO (n).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

CYCLIZATION OF NITRILES: LIX.
1663
Table 1. Characteristics of 3-methylsulfanyl-1-(2-thienyl)-4-cyano-5,6,7,8-tetrahydroisoquinolines Va n
Found, %
Calculated, %
Compd. Yield,
mp, oC (solvent
for crystallization)
Formula
no.
%
C
H
N
S
C
H
N
S
Va
Vb
Vc
Vd
Ve
Vf
Vg
Vh
Vi
Vj
Vk
Vl
Vm
Vn
74
81
76
79
92
84
90
95
62
93
94
98
81
86
47 48 (CHCl3)
65.28 6.10 8.60 19.30
58.12 3.90 6.60 14.54
63.36 4.40 7.10 17.69
69.21 5.20 7.81 17.50
59.70 4.01 6.62 14.20
58.64 3.88 6.61 14.71
63.30 4.40 7.20 16.01
58.71 3.20 9.31 14.22
65.20 5.08 9.01 20.42
63.28 5.01 9.70 14.62
62.24 4.40 9.71 15.03
58.56 4.34 9.10 13.52
63.00 4.30 6.78 14.92
60.30 4.01 6.22 13.80
C18H20N2S2
65.82 6.14 8.53 19.52
58.47 3.74 6.49 14.86
63.54 4.32 7.06 16.15
69.58 5.00 7.73 17.69
132 133 (CH3CN)
120 121 (CH3CN)
89 90 (CH3CN)
76 77 (CH3CN)
86 87 (CH3CN)
97 98 (CH3CN)
187 188 (CH3CN)
42 43 (C6H14)
175 176 (CH3CN)
220 221 (CH3CN)
205 206 (CH3CN)
198 199 (AcOH)
287 288 (AcOH)
C21H16Cl2N2S2
C21H17ClN2S2
C21H18N2S2
C22H17ClN2O2S2 59.92 3.89 6.35 14.54
C21H16Cl2N2S2
C21H17ClN2S2
C22H18ClN3OS
C17H16N2S2
C23H21N3O2S2
C22H18FN3OS2
C23H20ClN3O2S2 58.78 4.29 8.94 13.64
C22H17ClN2OS2 62.18 4.03 6.59 15.09
C22H16ClN2OS2 57.52 3.51 6.10 13.96
58.47 3.74 6.49 14.86
63.54 4.32 7.06 16.15
60.06 4.12 9.55 14.57
65.35 5.16 8.97 20.52
63.43 4.86 9.65 14.72
62.39 4.28 9.92 15.14
Table 2. IR and 1H NMR spectra of compounds Va n, VIn
Compd. IR spectrum,
1H NMR spectrum, , ppm
1
no.
Va
Vb
Vc
Vd
Ve
Vf
, cm
2220
2220
2225
2221
2222
2220
2225
1.22 s (6H, 2CH3), 1.86 s (4H, 2CH2), 2.11 q (1H, CH), 2.85 s (8H, 2CH2), 3.22 d (2H, CH2),
7.22 d (1H, H thiophene), 7.68 t (2H, H thiophene)
1.87 s (4H, 2CH2), 2.92 s (4H, 2CH2), 4.68 ©(2H, SCH2), 7.09 d (1H, H thiophene), 7.16 d
(1m, H thiophene), 7.39 d (1H, H thiophene), 7.56 7.69 d.d (3H, H arom)
1.83 s (4H, 2CH2), 2.91 m (4H, 2CH2), 4.45 s (2H, SCH2), 7.19 t (1H, H thiophene), 7.22 d
(2H, H thiophene ), 7.42 d (1H, H arom), 7.42 d (2H, H arom)
1.85 m (4H, 2CH2); 2.93 s (4H, 2CH2); 4.58 s (2H, SCH2), 7.17 7.58 m (8H, thiophene
and arom)
1.83 s (4H, 2CH2), 2.96 m (4H, 2CH2), 4.64 s (2H, SCH2), 5.94 s (2H, O CH2 O), 6.92 s (1H,
H arom), 7.03 s (1H, H arom), 7.19 t (1H, H thiophene), 7.62 d.d (2H, H thiophene)
1.86 s (4H, 2CH2), 2.92 s (4H, 2CH2), 4.65 s (2H, SCH2), 7.09 d (1H H thiophene), 7.16 d (1m,
H thiophene), 7.39 d (1H, H thiophene), 7.51 7.58 d.d (3H, H arom)
1.85 s (4H, 2CH2), 2.92 s (4H, 2CH2), 4.71 s (2H, SCH2), 7.15 m (3H, H thiophene), 7.36 7.57 m
(4m, H arom)
Vg
Vh
Vi
1670, 2224, 1.88 s (4H, 2CH2), 2.92 s (4H, 2CH2), 3.99 s (2H, SCH2), 7.01 d (2H, H arom), 7.16 t (1m,
3440
2222
H thiophene), 7.26 t (2H, arom), 7.51 d (2H, H arom), 9.33 br.s. (1m, NH)
1.89 s (4H, 2CH2), 2.95 s (4H, 2CH2), 3.92 d (2H, SCH2), 5.09 d (1H, cis-CH2=C), 5.33 d (1H
trans-CH2=C), 5.87 m1H, CH=C), 7.25 t (1H, H thiophene), 7.85 d (1H, H thiophene), 8.15 d.d
(1H, H thiophene)
Vj
1685, 3430, 1.85 s (4H, 2CH2), 2.93 s (4H, 2CH2), 3.61 s (3H, OCH3), 4.22 s (2H, SCH2), 6.95 t (2H,
2220
H arom), 7.17 t (1H, H thiophene), 7.67 d (1H, H thiophene), 7.73 d (1H, H thiophene), 8.01 d
(1H, H arom), 9.37 br.s (1m, NH)
Vk
Vl
1680, 3420, 1.88 s (4H, 2CH2), 2.97 s (4H, 2CH2), 4.01 s (2H, SCH2), 6.86 m (2H, H arom), 7.07 q(2H, arom),
2221 7.26 q(1H, H thiophene), 7.56 d (1H, H thiophene), 7.63 d (1H, H thiophene), 9.14 br.s (1H, NH)
1660, 3435, 1.83 s (4H, 2CH2), 2.91 s (4H, 2CH2), 3.69 s (3H, OCH3) 4.20 s (2H, SCH2), 6.95 d (2H, H arom),
2220 7.14 t (1H, H thiophene), 7.67 q (2H, H thiophene), 8.10 d (1H, H arom), 9.37 br.s (1m, NH)
Vm
Vn
VIo
1640, 2227 1.81 s (4H, 2CH2), 2.91 s (4H, 2CH2), 4.91 s (2H, SCH2), 7.17 t (1H, H thiophene), 7.55 d.d (4H,
H thiophene, H arom), 8.04 d (2m, H arom)
1645, 2235 1.83 H (4H, 2CH2), 2.93 d (2H, 2CH2), 4.65 s (2H, SCH2), 7.11 t (1H, H thiophene), 7.33 7.65 m
(5H, H arom)
1650, 3320 1.90 H (4H, 2CH2), 2.98 d (2H, CH2), 3.35 d (2H, CH2), 7.19 t (1H, H thiophene), 7.40 br.s
(2H, NH2), 7.92 s (1H, H arom), 8.07 s (2H, H arom)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

1664
LOZINSKII et al.
Table 3. Coordinates of atoms and equivalent isotropic
thermal parameters Ueq ( 2) in structure Va
acetamide (II) and 25 ml of triethylamine. The stir-
ring at 60 C was continued for 4 5 h, then the reac-
tion mixture was maintained for 2 h at room tempera-
ture, and acidified with 10% solution of HCl. The
precipitate was filtered off, washed with methanol,
and recrystallized from AcOH to obtain 6.94 g (85%)
Atom
x
e
z
Ueq
S1
0.56048(17) 0.14100(9) 0.99535(9) 0.0865
0.89993(12) 0.61716(8) 1.24823(8) 0.0648
1
S2
of compound III, mp 257 258 C. IR spectrum, cm :
1
N1
N2
C1
0.6945(30) 0.3786(2)
1.0273(2) 0.0490
2225 (CN), 3288 (NH). H NMR spectrum, , ppm:
0.3619(6)
0.7186(4)
0.6441(4)
0.5518(4)
0.5316(4)
0.6020(4)
0.6597(5)
0.5298(6)
0.5452(6)
0.4762(5)
0.4372(5)
0.8304(4)
0.8996(4)
1.0039(5)
1.0130(50
0.6917(5)
0.9025(6)
0.9845(9)
0.966(1)
0.0362(3) 0.6420(3) 0.0944
1.77 1.85 m (4H, CH2 CH2), 2.77 d (2H, CH2),
2.97 d (2H, CH2), 7.24 t (1H, C4 thiophene), 7.46 d
(1H, C5 thiophene), 7.65 d (1H, C3 thiophene),
10.67 br.s (1H, NH). Found, % : C 61.22; H 4.47;
N 10.31; S 23.19. C14H12N2S2. Calculated, %:
C 61.73; H 4.44; N 10.70; S 23.54.
0.4644(3)
0.4276(3)
0.2954(3)
0.2087(3)
0.2543(3)
0.5264(3)
0.4737(4)
0.3410(4)
0.2440(3)
0.0717(3)
0.5966(3)
0.7183(3)
0.8160(3)
0.7775(3)
0.2314(3)
0.2513(4)
0.3302(8)
0.1314(7)
0.9820(3) 0.0433
0.8459(3) 0.0458
0.7551(3) 0.0476
0.8035(3) 0.0512
0.9404(3) 0.0528
0.7986(3) 0.0599
0.6537(4) 0.0823
0.5665(4) 0.0802
0.6073(3) 0.0613
0.7134(3) 0.0650
1.0907(3) 0.0481
1.0933(3) 0.0609
1.2272(4) 0.0781
1.3176(4) 0.0695
1.1713(3) 0.0624
1.2155(4) 0.0863
1.3672(6) 0.1468
1.1699(8) 0.1622
C2
C3
C4
C5
C6
3-R-Methylsulfanyl-1-(2-thienyl)-4-cyano-5,6,7,8-
tetrahydroisoquinolines (Va n). General procedure.
To a solution of 5 mmol of isoquinolinethione III in
15 ml of DMF was added at stirring in succession
2.8 ml of 10% KOH solution and 10 mmol of halide
IVa n. The mixture was stirred at room temperature
for 1 h after the finish of reagents addition, and then
it was diluted with 20 ml of water. The separated
precipitate was filtered off, washed with aqueous
methanol (2: 1), and recrystallized from an appropri-
ate solvent. The data on compounds Va n are listed
in Tables 1 and 2.
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
3-Amino-2-(2,4-dichlorobenzoyl)-5-(2-thienyl)-
6,7,8,9-tetrahydrothieno[2,3-c]isoquinoline (VIn).
To a solution of 10 mmol of compound Vn in 5 ml
of DMF was added at stirring 3 ml of 10% water
solution of KOH. The cyclization completed in 2 h
(TLC monitoring). Then the mixture was diluted with
20 ml water. The precipitate was separated and re-
crystallized from AcOH to furnish 0.43 g (90%) of
torsional angles C2C3C49C8, C3C9C8C7, C9C8C7C6,
C8C7C6C2, C7C6C2C3 and C6C2C3C9 are equal to
11.9, 45.0, 62.5, 46.1, 12.9, 4.1 , modified
Cramer-Pople parameters [14] S,
and are 0.77,
29.0, and 38.7 respectively. The bond lengths and
angles in the compound Va molecule are of common
values [15, 16].
1
compound VIn, mp 261 262 C. IR spectrum, cm :
1
1650 (C=O), 3288, 3440 (NH). H NMR spectrum,
, ppm: 1.90 m (4H, CH2 CH2), 2.98 d (2H, CH2),
3.35 d (2H, CH2), 7.14 t (1H, C4 thiophene), 7.67 d
(1H, C5 thiophene), 7.62 d (1H, C3 thiophene),
7.49 br.s (2H, NH2) 7.43 7.98 m (3H, H arom).
Found, %: C 57.40; H 3.02; Cl 15.30; N 15.33;
S 13.19. C22H16Cl2N2OS2. Calculated, %: C 57.52;
H 3.51; Cl 15.43; N 6.10; S 13.96.
EXPERIMENTAL
IR spectra were measured on spectrophotometer
UR-20 from KBr pellets, 1H NMR spectra were
registered
on
spectrometer
Varian-VXR-300
(300 MHz) from solutions in DMSO with TMS as
internal reference. Melting points were determined
on Koeffler heating block. The reaction progress was
monitored and the homogeneity of the compounds
synthesized was checked by TLC on Silufol UV-254
plates, eluent acetone hexane, 5: 5, development
under UV irradiation or with iodine vapor.
X-ray diffraction analysis of a single crystal of
compound Va, crystal habit 0.34 0.50 0.56 was
carried out at room temperature on an automatic
four-circle diffractometer Enraf-Nonius CAD-4
(CuK -radiation, ratio of scanning rates /2 1.2,
70 , spherical segment 0
h
9, 14
k
14,
1-(2-Thienyl)-4-cyano-5,6,7,8-tetrahydro-3(2H)-
isoquinolinethione (II). To a mixture of 30 mmol of
2-(2-thenoyl)-1-cyclohexanone (I) and 50 ml of
methanol was added at stirring 30 mmol of cyanothio-
max
14
l
14). In total 3218 reflections was collected.
The absorption in the crystal was accounted for by the
method of azimuth scanning [17]. The crystals of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002

CYCLIZATION OF NITRILES: LIX.
1665
compound Va triclinic, a 7.448(1), b 11.757(3), c
6. Litvinov, V.P., Usp. Khimii, 1999, vol. 68, no. 9,
pp. 817 836.
11.953(1)
,
116.18(2), 105.52(1), 96.25(2) ,
3
V 873.3(4) 3, M 328.49, Z 2, dcalc 1.25 g cm ,
7. Goncharenko, M.P., Sharanin, Yu.A., Shestopa-
lov, A.M., Litvinov, V.P., and Turov, A.V., Zh. Org.
Khim., 1990, vol. 26, no. 7, pp. 1578 1588.
8. Freeman, F., Farqunar, D.R., and Walker, R.L.,
J. Org. Chem., 1968, vol. 33, pp. 3648 3653.
9. Vieweg, H., Hanfeld, V., Liestner, S., and Wagner, G.,
Pharmazie, 1989, vol. 44, no. 9, pp. 639 640.
10. Freeman, F. and Ito, T.I., J. Org. Chem., 1969,
vol. 34, pp. 3670 3672.
11. Sharanin, Yu.A., Shestopalov, A.M., Promonen-
kov, V.K., and Rodinovskaya, L.A., Zh. Org. Khim.,
1984, vol. 20, no. 11, pp. 2442 2448.
12. Sharanin, Yu.A., Shestopalov, A.M., Promonen-
kov, V.K., and Rodinovskaya, L. A., Zh. Org. Khim.,
1984, vol. 20, no. 11, pp. 2432 2441.
1
26.8 cm , F(000) 350, space group P 1 (N2). The
structure was solved by the direct method and refined
by the least-squares procedure in the full-matrix
anisotropic approximation with the use of software
package CRYSTALS [18]. In refining 2695 reflec-
tions were use with I > 3(I) (199 parameters refined,
number of reflections per parameter 13.5). All hydro-
gen atoms were revealed from the difference synthesis
of electron density and included in calculations with
fixed position and thermal parameters. We used in
refining the weight scheme of Chebyshev [19] with
four parameters: 0.65, 0.11, 0.20, and 0.34. The
final values of divergence factors are R 0.066 and
RW 0.063, GOF 1.040. The residual electron density
from the difference Fourier series amounts to 0.57
and 0.52 3. Coordinates of nonhydrogen atoms are
given in Table 1. The complete set of data on the
X-ray analysis of compound Va was deposited into
the Cambridge Structural Databank (no. 171738).
13. Vereshchagin, A.N., Usp. Khim., 1983, vol. 52,
no. 11, pp. 1879 1902.
14. Zefirov, N.C. and Palyulin, V.A., Dokl. Akad. Nauk
SSSR, 1980, vol. 252, no. 1, pp. 111 115.
15. Naumov, V.A. and Kataeva, O.N., Molekulyarnoe
stroenie organicheskikh soedinenii kisloroda i sery v
gazovoi faze (Molecular Structure of Oxygen and
Sulfur Organic Compounds in Gas Phase), Moscow:
Nauka, 1990, p. 192.
16. Allen, F.H., Kennard, O., Watson, D.G., Bram-
mer, L., Orpen, A.G., and Tailor, R., J. Chem. Soc.,
Perkin Trans. II, 1987, no. 12, pp. 1 19.
17. North, A.C.T., Phillips, D.C., Scott, F., and
Mathews, F.S., Acta Cryst. (A), 1968, vol. 24, no. 2,
P. 351 359.
18. Watkin, D.J., Prout, C.K., Carruthers, J.R., and
Betteridge, P.W., CRYSTALS, N 10, Chemical
Crystallography Laboratory, Univ. of Oxford. 1996,
pp. 1 210.
19. Carruthers, J.R. and Watkin, D.J., Acta Cryst. (A),
1979, vol. 35, no. 3, pp. 698 699.
REFERENCES
1. Sharanin, Yu.A., Cukharevskaya, L.Yu., and She-
lyakin, V.V., Zh. Org. Khim., 1998, vol. 34, no. 4,
pp. 586 588.
2. Glusa, E., Gruner, H., Hagen, A., Lohmann, D., and
Foker, H., Pharmazie, 1988, vol. 45, no. 6,
pp. 408 413.
3. Chorvat, R.G., Palmer, J.R., and Pappe, J. Org.
Chem., 1994, vol. 59, pp. 966 972.
4. German Patent 2202270, 1972; Chem. Abstr., 1972,
vol. 77, 151954.
5. Litvinov, V.P., Rodinovskaya, L.A., Sharanin, Yu.A.,
Shestopalov, A.M., and Senning, A., Sulfur Reports,
1992, vol. 13, no. 1, pp. 1 155.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 11 2002