An efficient procedure for the preparation of 4-methyl-2-thiocoumarins by the reaction of 4-methylcoumarins with lawesson's reagent

Article abstract of DOI:10.1002/jhet.5570420443

A simple and convenient method has been worked out for the preparation of 4-methyl-2-thiocoumarins by the reaction of the appropriate 4-methylcoumarins with Lawesson's Reagent in hot anhydrous toluene.

Full text of DOI:10.1002/jhet.5570420443

May-Jun 2005 An Efficient Procedure for the Preparation of 4-Methyl-2-thiocoumarins
by the Reaction of 4-Methylcoumarins with Lawesson's Reagent
739
*
Albert Lévai [a], and József Jek o´ ´ [b]
[a] Department of Organic Chemistry, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary,
[b] ICN Hungary Co. Ltd., H-4440 Tiszavasvári, Hungary
Received November 24, 2004
Dedicated to Professor Dr. Lubor Fisera on the occasion of his 60th birthday
A simple and convenient method has been worked out for the preparation of 4-methyl-2-thiocoumarins by
the reaction of the appropriate 4-methylcoumarins with Lawesson's Reagent in hot anhydrous toluene.
J. Heterocyclic Chem., 42, 739 (2005).
First synthesis of the 7-hydroxy-4-methylcoumarin (β-
methylumbelliferone) (1) was performed by von
Pechmann and Duisberg [1] as early as 1883 by the reac-
tion of resorcinol and ethyl acetoacetate. Later, von
Pechmann et al. [2,3] worked out other procedures for the
synthesis of this coumarin. Drysdale et al. [4] reacted
resorcinol and methyl 2,3-butadienoate to obtain
7
-hydroxy-4-methylcoumarin (1). Another method,
invented by Taylor and Cassell [5], is based on the reac-
tion of 2,4-dihydroxyacetophenone and trimethylsi-
lylketene and affords compound 1 in high (86%) yield.
This hydroxycoumarin was successfully utilized as start-
ing material for the synthesis of a wide variety of
4
-methylcoumarin derivatives.
-Methylcoumarin-7-yloxy tetra-N-acetyl-β-chitotetro-
4
side and similar β-chitotrioside were obtained under
Koenigs-Knorr reaction conditions [6]. A neuraminic acid
derivative has also been synthesized [7]. All these glyco-
sides were utilized for enzyme inhibition studies [6,7].
Sulfate and sulfamate derivatives were synthesized for
steroid sulfatase assay [8]. Various 7-alkoxy-4-methyl-
coumarins, including β-lactam [9], benzyloxy [10],
phenazine [11] and carboxymethyl derivatives [12] were pre-
pared by the reaction of the 7-hydroxy group of compound 1
with the appropriate reagent. Most of these coumarins were
used for enzyme inhibition studies and other biological pur-
poses. All these examples unequivocally prove the synthetic
utility of the β-umbelliferone even today.
Various 7-benzyloxycoumarins have already been syn-
thesized for enzyme inhibition studies [10]. On the basis of
the results obtained with these compounds, it appeared
expedient to synthesize a series of 7-benzyloxy-4-methyl-
coumarins systematically substituted in their benzyl moi-
ety. Compound 1 was allowed to react with benzyl chlo-
rides substituted either with an electron donor or an elec-
tron acceptor substituent in hot acetone solution to afford
new 7-benzyloxy-4-methylcoumarins 3-11 in high (71-
Although numerous 4-methylcoumarin derivatives have
been synthesized, their conversion into 4-methyl-2-thio-
coumarins has hitherto received less attention. 7-Methoxy-
4
7
-methyl-2-thiocoumarin was prepared by the reaction of
-methoxy-4-methylcoumarin with silicon disulphide or
boron sulphide [13] in refluxing chloroform and with
phosphorus pentasulphide [14] in hot benzene. However,
these reagents sometimes require special care which may
be a disadvantage concerning their utilization. The conse-
quence of this difficulty is that nowadays these reagents
are almost out of use.
In our previous studies, Lawesson's Reagent [2,4-bis(4-
methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disul-
fide] [15] proved to be the reagent of choice for the
replacement of an oxygen atom by a sulfur atom in the case
of chromones [16], 1-thiochromones [17], flavones [18],
isoflavones [16], 1,4- and 1,5-benzoxazepines [19-21] and
1,5-benzothiazepines [22]. Therefore, this reagent has been
considered convenient for the conversion of 4-methyl-
coumarins into 4-methyl-2-thiocoumarins as well.
7-Benzyloxy-4-methylcoumarins 2-11 were allowed
to react with Lawesson's Reagent [15] in hot anhydrous
toluene and 7-benzyloxy-4-methyl-2-thiocoumarins 12-
21 were obtained in high (75-91%) yields (Scheme 1).
9
3%) yields (Scheme 1). The new coumarin derivatives
can be advantageously utilized for the study of structure-
activity relationships.

7
40
A. Lévai and J. Jek o´ ´
Vol. 42
7
4
-Benzenesulfonyloxy-4-methylcoumarin (22) [23] and
-methyl-7-tosyloxycoumarin (23) [23] have also been
sium iodide (0.5 g), potassium carbonate (10.0 g) and anhydrous
acetone (200 ml) was refluxed for 6 h, then the inorganic salts
were removed by filtration. The solvent was evaporated under
reduced pressure and the residue was crystallized from methanol
to obtain compounds 3-11.
treated with Lawesson's Reagent under the same reaction
conditions to afford the 2-thioanalogues 24 and 25 in
high (89% and 90%) yields (Scheme 2).
Structures of all new compounds (3-11, 12-21, 24 and
4-Methyl-7-(2-methylbenzyloxy)coumarin (3).
2
5) have been elucidated by elemental analyses, mass
This compound was prepared as white needles in 90% yield,
1
13
spectrometry, H and C nmr spectroscopies (cf.
1
mp 148-149°; H nmr: δ 2.50 (3H, s, Me), 2.52 (3H, s, Me), 5.12
1
13
13
Experimental). Both H and C nmr spectra unequivo-
cally prove the structure of each compound. Formation
of the 4-methyl-2-thiocoumarin derivatives is reflected
in the downfield shift of the 3-H proton signal in their H
nmr spectra. In the C nmr spcetra a C=S signal appears
at around 197 ppm instead of the C=O signal at about
(2H, s, CH ), 6.18 (1H, s, 3-H), 6.93-7.56 (m, 7 arom. H);
C
2
nmr: δ 18.3, 18.6, 69.9, 101.8, 112.0, 112.8, 113.8, 125.6, 126.2,
1
28.7, 130.6, 133.7, 136.8, 152.6, 155.3, 161.3, 161.9; ms: 280
+
1
(M , 5), 176 (2), 147 (2), 105 (100) m/z.
Anal. Calcd. for C18H16O : C, 77.12; H, 5.75. Found: C,
1
3
3
7
4
7.26; H, 5.78.
-Methyl-7-(3-methylbenzyloxy)coumarin (4).
1
61 ppm.
Electron impact (70 eV) mass spectra of these
This substance was obtained as white needles in 85% yield, mp
1
coumarins are very similar and relatively simple. A molec-
ular ion can be observed in all cases and the base peak is
94-95°; H nmr: δ 2.50 (3H, s, Me), 2.53 (3H, s, Me), 5.12 (2H, s,
1
3
CH2), 6.17 (1H, s, 3-H), 6.91-7.57 (m, 7 arom. H); C nmr: δ
+
18.4, 21.2, 70.5, 101.2, 112.1, 112.9, 113.8, 124.7, 125.6, 128.3,
mainly the Ar(R)-CH2 ion. Fragmentation of the
1
(
28.7, 129.2, 135.9, 138.9, 152.6, 155.4, 161.4, 161.9; ms: 280
coumarin ring system corroborates the structures eluci-
dated by nmr spectroscopic measurements.
+
M ,11), 176 (3), 147 (3), 105 (100) m/z.
Anal. Calcd. for C H O : C, 77.12; H, 5.75. Found: C,
1
8 16 3
In summary, we have introduced a simple and conve-
nient procedure for the preparation of 4-methyl-2-thio-
coumarins. The Lawesson's Reagent could be advanta-
geously utilized in the case of these coumarin deriva-
tives for the replacement of an oxygen atom by a sulfur
atom, too.
7
4
7.29; H, 5.69.
-Methyl-7-(4-methylbenzyloxy)coumarin (5).
This compound was isolated as white needles in 79% yield, mp
1
1
25-126°; H nmr: δ 2.50 (3H, s, Me), 2.53 (3H, s, Me), 5.10
13
(2H, s, CH ), 6.14 (1H, s, 3-H), 6.90-7.53 (m, 7 arom. H);
C
2
nmr: δ 18.3, 20.9, 70.3, 101.9, 111.9, 112.9, 113.7, 125.6, 127.7,
+
1
1
29.5, 132.9, 138.3, 152.6, 155.3, 161.4, 161.9; ms: 280 (M , 4),
EXPERIMENTAL
76 (2), 147 (2), 105 (100) m/z.
Anal. Calcd. for C18H16O : C, 77.12; H, 5.75. Found: C,
3
Melting points were determined with a Koffler hot-stage appa-
ratus and are uncorrected. Nmr spectra were recorded on the
77.34; H, 5.72.
7
-(2-Fluorobenzyloxy)-4-methylcoumarin (6).
Varian 200 spectrometer at 200/50 MHz in CDCl (internal stan-
3
dard TMS, δ = 0.0 ppm) at room temperature. Mass spectra were
measured on the VG TRIO-2 in the EI mode at 70 eV. Elemental
analyses were measured in-house with a Carlo Erba 1106 EA
apparatus. Tlc was performed on Kieselgel 60 F254 (Merck) layer
using 1,2-dichloroethane or hexane:acetone (7:3 v/v) as eluents.
Starting materials 1, 2, 22 and 23 were synthesized according to
known procedures [10,23].
This substance was prepared as white plates in 74% yield, mp
1
146-147°; H nmr: δ 2.51 (3H, s, Me), 5.23 (2H, s, CH ), 6.18
2
1
3
(1H, s, 3-H), 6.92-7.57 (m, 7 arom. H); C nmr: δ 18.3, 64.1,
101.9, 112.1, 112.6, 113.9, 115.3, 115.7, 124.4, 125.7, 129.8,
+
130.3, 152.6, 155.3, 161.2, 161.6; ms: 284 (M , 8), 176 (2), 147
(2), 109 (100) m/z.
Anal. Calcd. for C H FO : C, 71.82; H, 4.61. Found: C,
1
7
13
3
7
1.75; H, 4.66.
General Procedure for the Preparation of 7-Benzyloxy-4-methyl-
coumarins 3-11.
7-(3-Fluorobenzyloxy)-4-methylcoumarin (7).
A mixture of 7-hydroxy-4-methylcoumarin (1, 20.0 mmoles),
appropriately substituted benzyl chloride (22.0 mmoles), potas-
This compound was obtained as white plates in 80% yield, mp
1
149-150°; H nmr: δ 2.44 (3H, s, Me), 5.17 (2H, s, CH ), 6.18
2

May-Jun 2005
Communication to the Editor
741
(
1
1
1H, s, 3-H), 6.88-7.54 (m, 7 arom. H); 13C nmr: δ 18.4, 69.5,
91 (100) m/z.
Anal. Calcd. for C H O S: C, 72.33; H, 4.99. Found: C,
72.46; H, 4.92.
01.9, 112.2, 112.8, 114.0, 114.5, 115.0, 115.4, 122.8, 125.7,
1
7 14 2
+
30.5, 138.6, 152.6, 155.4, 161.3, 161.5; ms: 284 (M , 11), 176
(
2), 147 (2), 109 (100) m/z.
4
-Methyl-7-(2-methylbenzyloxy)-2-thiocoumarin (13).
Anal. Calcd. for C H FO : C, 71.82; H, 4.61. Found: C,
1
7
13
3
7
7
1.78; H, 4.64.
This compound was isolated as yellow needles in 89% yield,
1
mp 148-149°; H nmr: δ 2.35 (3H, s, Me), 2.40 (3H, s, Me), 5.12
-(4-Fluorobenzyloxy)-4-methylcoumarin (8).
13
(
2H, s, CH ), 6.96-7.60 (m, 3-H + 7 arom. H); C nmr: δ 17.8,
2
1
8.6, 69.2, 101.7, 114.7, 115.5, 125.6, 126.3, 126.7, 128.6, 128.8,
This substance was prepared as white plates in 87% yield, mp
+
1
130.7, 133.5, 136.7, 145.0, 158.1, 162.4, 197.6; ms: 296 (M ,
11), 218 (10), 155 (8), 105 (100) m/z.
1
(
1
1
34-135°; H nmr: δ 2.44 (3H, s, Me), 5.11 (2H, s, CH ), 6.16
2
1H, s, 3-H), 6.89-756 (m, 7 arom. H); 1 C nmr: δ 18.4, 69.7,
3
Anal. Calcd. for C H O S: C, 72.96; H, 5.44. Found: C,
01.9, 112.2, 112.8, 113.9, 115.5, 115.9, 125.7, 129.6, 131.7,
18 16 2
+
72.982; H, 5.49.
52.6, 155.4, 161.3, 161.7; ms: 284 (M , 5), 262 (1), 147 (3), 109
(
100) m/z.
4
-Methyl-7-(3-methylbenzyloxy)-2-thiocoumarin (14).
Anal. Calcd. for C17H13FO : C.71.82; H, 4.61. Found: C,
1.89; H, 4.64.
3
This substance was obtained as yellow needles in 76% yield,
7
7
1
mp 127-128°; H nmr: δ 2.31 (3H, s, Me), 2.38 (3H, s, Me), 5.08
-(2-Chlorobenzyloxy)-4-methylcoumarin (9).
This substance was obtained as pale yellow needles in 93%
13
(2H, s, CH ), 6.97-7.56 (m, 3-H + 7 arom. H); C nmr: δ 17.8,
2
2
1.2, 70.6, 101.4, 114.8, 115.5, 124.6, 125.6, 126.7, 128.3, 128.8,
+
1
129.3, 135.6, 138.6, 145.0, 158.0, 162.3, 197.6; ms: 296 (M ,
19), 264 (3), 155 (6), 105 (100) m/z.
Anal. Calcd. for C18H16O2S: C, 72.96; H, 5.44. Found: C,
73.11; H, 5.37.
yield, mp 154-155°; H nmr: δ 2.41 (3H, s, Me), 5.26 (2H, s.
CH ), 6.17 (1H, s, 3-H), 6.90-7.53 (m, 7 arom. H); C nmr: δ
1
1
1
1
3
2
8.4, 67.5, 102.2, 112.3, 112.7, 114.0, 125.7, 127.2, 128.9, 129.5,
29.7, 132.9, 133.7, 152.6, 155.4, 161.3, 161.6; ms: 300 (M , 8),
76 (2), 147 (2), 125 (100) m/z.
Anal. Calcd. for C H ClO : C, 67.89; H, 4.36. Found: C,
+
4
-Methyl-7-(4-methylbenzyloxy)-2-thiocoumarin (15).
1
7
13
3
This compound was prepared as yellow needles in 75% yield,
6
7
7.98; H, 4.31.
1
mp 164-165°; H nmr: δ 2.32 (3H, s, Me), 2.38 (3H, s, Me), 5.10
-(4-Chlorobenzyloxy)-4-methylcoumarin (10).
13
(2H, s, CH ), 6.97-7.56 (m, 3-H + 7 arom. H); C nmr: δ 17.7,
2
This compound was prepared as pale yellow plates in 88%
20.9, 70.4, 101.4, 114.7, 115.3, 125.5, 126.6, 127.6, 129.5, 132.6,
1
138.3, 145.0, 157.9, 162.3, 197.5; ms: 296 (M+, 16), 264 (2), 147
yield, mp 139-140°; H nmr: δ 2.42 (3H, s, Me), 5.12 (2H, s,
1
3
(3), 105 (100) m/z.
Anal. Calcd. for C18H16O2S: C, 72.96; H, 5.44. Found: C,
72.84; H, 5.48.
CH ), 6.17 (1H, s, 3-H), 6.88-7.52 (m, 7 arom. H); C nmr: δ
2
1
1
8.3, 69.5, 101.9, 112.2, 112.8, 113.9, 125.7, 128.8, 128.9, 134.2,
+
34.5, 152.6, 155.3, 161.2, 161.6; ms: 300 (M , 6), 176 (2), 147
(
4), 125 (100) m/z.
Anal. Calcd. for C H ClO : C, 67.89; H, 4.36. Found: C,
7.98; H, 4.32.
7
-(2-Fluorobenzyloxy)-4-methyl-2-thiocoumarin (16).
1
7
13
3
This substance was obtained as yellow plates in 91% yield, mp
6
4
1
2
7
01-202°; H nmr: δ 2.37 (3H, s, Me), 5.11 (2H, s, CH ), 6.97-
2
-Methyl-7-(4-nitrobenzyloxy)coumarin (11).
13
.60 (m, 3-H + 7 arom. H); C nmr: δ 17.8, 64.4, 101.5, 114.6,
This substance was obtained as yellow needles in 71% yield,
115.5, 115.9, 124.5, 125.7, 126.9, 129.8, 130.4, 130.6, 144.9,
1
158.0, 162.0, 197.6; ms: 300 (M+, 22), 268 (3), 147 (2), 109 (100)
mp 204-205°; H nmr: δ 2.44 (3H, s, Me), 5.24 (2H, s, CH ), 6.18
2
(
1H, s, 3-H), 6.87-8.30 (m, 7 arom. H); 13C nmr: δ 18.0, 68.6,
m/z.
1
1
1
01.9, 111.6, 112.8, 113.7, 123.8, 126.8, 128.6, 144.4, 147.4,
53.6, 154.9, 160.3, 161.2; ms: 311 (M , 10), 176 (2), 147 (2),
36 (100) m/z.
Anal. Calcd. for C17H13FO2S: C, 67.99; H, 4.36. Found: C,
67.85; H, 4.31.
+
7
-(3-Fluorobenzyloxy)-4-methyl-2-thiocoumarin (17).
Anal. Calcd. for C17H13NO : C, 65.59; H, 4.21; N, 4.49.
5
This compound was prepared as yellow plates in 75% yield,
Found: C, 65.48; H, 4.25; N, 4.43.
1
mp 147-148°; H nmr: δ 2.34 (3H, s, Me), 5.14 (2H, s, CH ),
2
General Procedure for the Preparation of 4-Methyl-2-thio-
coumarins 12-21, 24 and 25.
13
6
1
.96-7.58 (m, 3-H + 7 arom. H); C nmr: δ 17.7, 69.6, 101.4,
14.0, 115.1, 115.7, 122.8, 125.7, 126.8, 130.6, 138.3, 144.9,
+
A mixture of 4-methylcoumarin (2-11, 22 and 23, 5.0 mmoles),
Lawesson's Reagent (6.0 mmoles) and anhydrous toluene (30 ml)
was refluxed for 3 h and then the solvent was evaporated under
reduced pressure. The residue was crystallized from methanol to
afford 4-methyl-2-thiocoumarins 12-21, 24 and 25.
157.9, 161.9, 165.6, 197.5; ms: 300 (M , 19), 268 (4), 147 (2),
109 (100) m/z.
Anal. Calcd. for C H FO S: C, 67.99; H, 4.36. Found: C,
1
7
13
2
68.12; H, 4.29.
7
-(4-Fluorobenzyloxy)-4-methyl-2-thiocoumarin (18).
7
-Benzyloxy-4-methyl-2-thiocoumarin (12).
This compound was obtained as yellow needles in 82% yield,
1
This compound was obtained as yellow needles in 77%
mp 135-136°; H nmr: δ 2.36 (3H, s, Me), 5.10 (2H, s, CH ),
2
1
13
yield, mp 151-152°; H nmr: δ 2.32 (3H, s, Me), 5.14 (2H, s.
CH ), 6.97-7.58 (m, 3-H + 8 arom. H); C nmr: δ 17.7, 70.5,
1
1
6.96-7.60 (m, 3-H + 7 arom. H); C nmr: δ 17.7, 69.8, 101.4,
1
3
114.7, 115.6, 116.0, 125.7, 126.8, 129.4, 129.6, 131.4, 144.9,
2
+
01.5, 114.7, 115.5, 125.6, 126.7, 127.5, 128.5, 128.9, 135.7,
158.0, 160.4, 162.0, 165.4, 197.6; ms: 300 (M , 13), 268 (2), 147
+
44.9, 158.0, 162.2, 197.6; ms: 282 (M , 17), 250 (3), 136 (3),
(2), 109 (100) m/z.

742
A. Lévai and J. Jek o´ ´
Vol. 42
Anal. Calcd. for C H FO S: C, 67.99; H, 4.36. Found: C,
Acknowledgements.
1
7
13
2
6
7
7.81; H, 4.27.
The present study was sponsored by the Hungarian National
Research Foundation (Grant No. OTKA T034123) for which our
gratitude is expressed. Technical assistance of Mrs. M. Nagy is
highly appreciated.
-(2-Chlorobenzyloxy)-4-methyl-2-thiocoumarin (19).
This substance was prepared as yellow plates in 88% yield, mp
1
171-172°; H nmr: δ 2.36 (3H, s, Me), 5.26 (2H, s, CH ), 7.03-
2
1
3
7
1
62 (m, 3-H + 7 arom. H); C nmr: δ 17.8, 67.7, 101.6, 114.5,
15.7, 125.7, 126.9, 128.8, 129.6, 132.9, 133.4, 144.9, 158.0,
REFERENCES AND NOTES
+
161.9, 197.6; ms: 316 (M , 15), 284 (2), 147 (2), 125 (100) m/z.
Anal. Calcd. for C17H13ClO S: C, 64.46; H, 4.14. Found:
4.38; H, 4.19.
2
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6, 2119 (1883).
6
7
1
3
[2] H. von Pechmann and O. Schwarz, Ber. Dtsch. Chem. Ges.,
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1
mp 155-156°; H nmr: δ 2.34 (3H, s, Me), 5.12 (2H, s, CH ),
2
1
3
6
1
1
(
.97-7-59 (m, 3-H + 7 arom. H); C nmr: δ 17.8, 69.7, 101.5,
14.6, 115.6, 125.7, 126.9, 128.9, 129.0, 134.2, 134.4, 144.9,
57.9, 161.9, 197.5; ms: 316 (M , 12), 284 (2), 147 (2), 125
100) m/z.
Anal. Calcd. for C H ClO S: C, 64.46; H, 4.14. Found: C,
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+
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7
13
2
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4
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Lawesson, Bull. Chem. Soc. Belges, 87, 223 (1978).
1
mp 198-199°; H nmr: δ 2.32 (3H, s, Me), 5.25 (2H, s, CH ),
2
1
3
6
.98-8.26 (m, 3-H + 7 arom. H); C nmr: δ 17.7, 69.1, 101.5,
114.1, 115.9, 124.0, 125.9, 127.0, 127.8, 143.1, 144.7, 147.9,
+
1
(
57.9, 161.5, 197.5; ms: 327 (M , 60), 281 (11), 192 (43), 148
100) m/z.
Anal. Calcd. for C H NO S: C, 62.38; H, 4.01; N, 4.28.
[
1
7
13
4
Found: C, 62.51; H, 4.08; N, 4.21.
[
4
7
-Benzenesulfonyloxy-4-methyl-2-thiocoumarin (24).
[
This substance was obtained as yellow needles in 89% yield,
2
1
mp 177-178°; H nmr: δ 2.34 (3H, s, Me), 7.03-7.90 (m, 3-H + 8
arom. H). 13C nmr: δ 17.7, 55.4, 95.0, 96.2, 110.6, 119.7, 125.8,
1
[
28.4, 129.2, 129.6, 134.9, 143.2, 151.7, 156.3, 197.0; ms: 332
+
(M , 57), 191 (24), 141 (46), 77 (100) m/z.
[
[
[
16] A. Lévai, J. Chem. Research (S), 163 (1992).
17] A. Lévai and Z. Szabó, Bull.Chim. Soc. Fr., 128, 976 (1991).
18] A. Lévai and Z. Szabó, J. Chem. Research (S), 380 (1992).
Anal. Calcd. for C H O S : C, 57.83; H, 3.64. Found: 57.95;
1
6 12 4 2
H, 3.56.
4
-Methyl-7-tosyloxy-2-thiocoumarin (25).
[19] A. Lévai, T. Tímár, L. Frank and S. Hosztafi, Heterocycles,
4, 1523 (1992).
3
This compound was prepared as yellow needles in 90% yield,
[20] A. Lévai and Z. Bálint, Arch. Pharm. (Weinheim), 326, 73
1
mp 140-141° ; H nmr: δ 2.l9 (3H, s, Me), 2.26 (3H, s, Me), 7.04-
(
1993).
1
3
7
1
3
.80 (m, 3-H + 7 arom. H), C nmr: δ 17.7, 21.6, 120.0, 120.4,
[21] G. Tóth, J. Halász, A. Lévai and B. Rezessy, Monatsh. Chem.,
25.7, 128.5, 129.2, 130.2, 143.2, 146.3, 151.9, 156.4, 197.2; ms:
1
28, 625 (1997).
+
46 (M , 27), 314 (4), 155 (46), 91 (100) m/z.
[22] A. Lévai, Arch. Pharm. (Weinheim), 325, 721 (1992).
[23] A. A. Shamshurin and R. A. Ibadulin, Trudy Uzbekskogo
Anal. Calcd. for C H O S : C, 58.96; H, 4.07. Found: C,
1
7 14 4 2
5
8.84; H, 4.13.
Gosudarst. Univ., 1 (1941); Chem. Abstr., 35, 37638 (1941).