Thionation of chalcone and aurone derivatives by Lawesson's reagent

Article abstract of DOI:10.1080/10426507.2012.704457

The reaction of Lawesson's reagent (LR 5) with chalcones (4a-h) and aurones (12a-h) proceeds in refluxing toluene to give the respective benzofuranylprop-2-en-1-thiones (8a-h) and benzodifuran-3-thiones (13a-h). Correct elemental analyses and spectroscopi

Full text of DOI:10.1080/10426507.2012.704457

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Phosphorus, Sulfur, and Silicon and the
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Thionation of Chalcone and Aurone
Derivatives by Lawesson's Reagent
Eman Elhefny a b
a Photochemistry Department , National Research Centre , Dokki ,
Cairo , Egypt
b Chemistry Department, Faculty of Science , Jazan University ,
Jazan , Saudi Arabia
Accepted author version posted online: 26 Jun 2012.Published
online: 31 May 2013.
To cite this article: Eman Elhefny (2013): Thionation of Chalcone and Aurone Derivatives by
Lawesson's Reagent, Phosphorus, Sulfur, and Silicon and the Related Elements, 188:6, 804-811
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Phosphorus, Sulfur, and Silicon, 188:804–811, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.704457
THIONATION OF CHALCONE AND AURONE DERIVATIVES
BY LAWESSON’S REAGENT
Eman Elhefny
Photochemistry Department, National Research Centre, Dokki, Cairo, Egypt
Chemistry Department, Faculty of Science, Jazan University, Jazan, Saudi Arabia
GRAPHICAL ABSTRACT
Abstract The reaction of Lawesson’s reagent (LR 5) with chalcones (4a–h) and aurones
(12a–h) proceeds in refluxing toluene to give the respective benzofuranylprop-2-en-1-thiones
(8a–h) and benzodifuran-3-thiones (13a–h). Correct elemental analyses and spectroscopic
data were obtained for the new compounds.
Keywords Lawesson reagent; chalcones; aurones
INTRODUCTION
It has been reported1,2 that condensation of visnaginone (2a) and khelleinone (2b)
with p-chlorobenzaldehyde, p-methoxybenzaldehyde, 2,4-dimethoxybenzaldehyde, and p-
nitrobenzaldehyde yields the respective chalcones (4a–h).3,4 Compounds 2a and 2b are
essentially prepared by the alkaline hydrolysis of visnagin (1a) and khaellin (1b), respec-
tively (Scheme 1).
Chalcones and several of their derivatives inhibit the voltage-gated potassium chan-
nel, which constitutes a promising new target for the treatment of T-cell-mediated autoim-
mune diseases, such as sclerosis.5 Besides their well-known biological activity, they are
used as precursors for the synthesis of many heterocyclic compounds, such as pyrazoles,
pyrazolines, and flavones.6,7
In the course of our continuing studies on the chemistry of chalcones,7 it was of interest
to investigate the reaction of the prop-2-en-1-one derivatives (4a–h) toward Lawesson’s
reagent (LR 5). Aromatic ketones react with 5 to give, in most cases, the corresponding
thioketones.8–11 The chemistry of Lawesson’s reagent 5 (LR 5) and related reagents has
Received 22 August 2011; accepted 6 June 2012.
Address correspondence to Eman Elhefny, Photochemistry Department, National Research Centre, Dokki,
Cairo, Egypt. E-mail: emanelhefny@yahoo.com
804

THIONATION OF CHALCONE BY LAWESSON’S REAGENT
805
Scheme 1
been reviewed by several groups of investigators,12–14 taking into consideration that their
main use is the thionation of carbonyl compounds, such as ketones,15–17 carboxamides,18
esters,19 enaminones,20 lactams,21 and γ , δ-lactones.22
RESULTS AND DISCUSSION
It has been now found that chalcones 4a–h react with LR 5 in 1:1 molar ratios in
refluxing dry toluene to give crystalline compounds, for which the (3-aryl-1-benzofuran-5-
yl)propen-1-thione structures 8a–h were assigned (Scheme 2).
Compounds 8a–h are chromatographically pure and readily soluble in 90% aqueous
NaOH. It is worth to mention that, the reaction of 2a,b with the same reagent 5, on the
other hand, gives the cyclic 1,2-oxaphosphinanes 11a,b, respectively23 (Figure 1).
A possible mechanism of formation of compounds 8 is depicted in Scheme 2. Initial
nucleophilic attack by LR in its monomer form 5B on the carbonyl carbon atom in 4
can give the betaine intermediate 6, which cyclizes to form the transient species 7. From
these species the oxa thio phosphorane 9 is eliminated yielding the final thioketones 8.
Dimerization of 9 yields the dioxoanalogue 1024 of LR 5.
Satisfactory micro-analytical and spectroscopic data were obtained for compounds
8a–h. Thus, the IR spectrum (KBr) of 8a, taken as an example, showed the presence of
the thiocarbonyl band at 1345 cm−1. The strong carbonyl band present in the spectrum of

806
E. ELHEFNY
Scheme 2
chalcone 4a at 1730 cm−1 was absent in the spectrum of 8a. Its mass spectrum (MS) showed
an ion peak at m/e = 328.5 [M+]. Its 1H NMR spectrum [dimethylsulfoxide (DMSO)-d6]
showed signals at δ = 3.88 (s, 3H, OCH3), 4.00 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H),
7.20 (s, 1H, olefinic-H), 7.60 (s, 1H, furane); 7.18 (s, 1H, furane), 7.90 (d, J = 9.2 Hz, 2H,
aromtic-H), 8.18 (d, J = 9.2 Hz, 2H, aromtic-H), 12.66 (s, 1H, OH, exchangeable with
D2O).
The aurones 12a–h were prepared according to an established procedure by oxidation
of the chalcones 4a–h with hydrogen peroxide.4 Compounds 12a–h were allowed to react

THIONATION OF CHALCONE BY LAWESSON’S REAGENT
807
Figure 1 Cyclic 1,2-oxaphosphinone structures 11a,b.
with LR 5 in boiling toluene to give the corresponding benzo[1,2-b:5,4-b]difuran-3-thiones
13a–h (Scheme 3). Compatible elemental analyses and spectroscopic measurements were
obtained for the isolated thioketones 13a–h (see experimental section).
Scheme 3
Satisfactory micro-analytical and spectroscopic measurements were obtained for
compounds 13a–h. The IR spectrum (KBr, cm−1) of 13a, taken as an example, shows
characteristic bands at 3415 cm−1 (OH), 3295 cm−1 (C H), 3280–3270 cm−1 (aliphatic
protons), and 1345 cm−1 (C S). Its MS shows an ion peak at m/e = 342.5 [M+]. The
proton spectrum further supports the structure of 13a (see Experimental section).
CONCLUSIONS
In summary, we report a study on the thionation of chalcones and aurones using LR.
Benzofuranylprop-2-en-1-thiones 8a–h and benzodifuran-3-thiones 13a–h were obtained
in high yields of 96–98% and 65–80%, respectively.
EXPERIMENTAL
Synthetic Methods, Analytical, and Spectral Data
Melting points (mp) were determined with an electrothermal apparatus (Buchi 535) in
an open capillary tube and are uncorrected. The IR spectra were recorded in KBr pellets with
a PA-9721 IR spectrophotometer. The 1H NMR spectra were obtained with a Varian EM-
390 spectrometer in CDCl3 as solvent using tetramethylsilane (TMS) as internal reference.
Chemical shifts (δ) are given in ppm. The MS were recorded with Kratos (70 eV) Ms

808
E. ELHEFNY
Equipment. The elemental analyses were carried out by the micro-analytical unit at the
National Research Centre, Giza, Egypt.
All reactions were monitored by thin layer chromatography (TLC) carried out on
0.2 mm silica gel 60 F-254 (Merck) plates using UV light (254 and 366 nm) for detection.
Column chromatography was carried out on a Baker silica gel powder (60–200 mesh).
Synthesis of Compounds 8a–h: General Procedure
To a suspension of 4a–h (0.01 mol) in dry toluene (30 mL) LR (0.404 g, 0.001 mol)
was added. The reaction mixture was stirred at refluxing temperature until no more of the
starting materials were detected by TLC. The solvent was evaporated under vacuum and
the remaining solids were treated with the proper solvent for crystallization.
1-(6-Hydroxy-4-methoxy-1-benzofuran-5-yl)-3-(2-methoxy-4-
chlorophenyl)2,4-dienyl)propene thione (8a). Yield 97%, mp 113 ◦C, brown
crystals (from benzene). MS, m/z: (344.5, 20.5%). IR (KBr), ν (cm−1): 3425 (OH), 3290
1
(CH, aromatic), 2885 (CH, aliphatic), 1345 (C S). H NMR (270 MHz, CDCl3, TMS):
δ = 3.88 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H, olefinic-H), 6.60 (s, 1H,
furane-H), 7.18 (s, 1H, furane-H), 7.18 (m, 2H, arom-H), 7.80 (m, 2H, arom-H), 12.66
(s, 1H, OH, exchangeable with D2O). Anal. calcd. for C18H13ClO3S: C 62.70, H 3.80, S
9.30%. Found: C 62.69, H 3.77, S 9.31%.
1-(6-Hydroxy-4-methoxy-1-benzofuran-5-yl)-3-(2,4-dimethoxyphenyl-
◦
2,4-dienyl)propene-1-thione (8b). Yield 98%, mp 127 C (MeOH). MS, m/z: (340,
21%). IR (KBr), ν (cm−1): 3445 (OH), 3292 (CH, aromatic), 2885 (CH, aliphatic),
1
1351 (C S). H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s, 3H, OCH3); 6.60 (s, 1H,
olefinic-H); 7.20 (s, 1H, olefinic-H); 6.60 (s, 1H, furane-H); 7.18 (s, 1H, furane-H); 6.66
(m, 2H, arom-H); 7.70 (m, 2H, arom-H); 12.66 (s, 1H, OH, exchangeable with D2O).
Anal. calcd. for C19H16O4S: C 67.04, H 4.74, S, 9.42%. Found: C 67.20, H 4.79, S 9.41%.
1-(6-Hydroxy-4-methoxy-1-benzofuran-5-yl)-3-(2-methoxy-2,4-
dienyl)propene-1-thione (8c). Yield 98%, mp 145 ◦C, orange crystals (from
benzene). MS, m/z: (370, 22.8%). IR (KBr), ν (cm−1): 3445 (OH), 3290 (CH, aromatic),
2885 (CH, aliphatic), 1345 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s, 3H,
OCH3), 4.00 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H, olefinic-H); 6.60 (s, 1H,
furane-H), 7.18 (s, 1H, furane-H), 7.18 (m, 2H, arom-H), 7.80 (m, 2H, arom-H), 12.66 (s,
1H, OH, exchangeable with D2O). Anal. calcd. for C20H18O5S: C 64.85, H, 4.85, S 8.66%.
Found: C 64.86, H 4.86, S 8.64%.
1-(6-Hydroxy-4-methoxy-1-benzofuran-5-yl)-3-(2-methoxy-4-nitrophenyl-
2,4-dienyl)propene thione (8d). Yield 98%, mp 220 ◦C, reddish crystals (from
benzene). MS, m/z: (355, 66%). IR (KBr), ν (cm−1): 3425 (OH), 3290 (CH, aromatic),
2885 (CH, aliphatic), 1345 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s, 3H,
OCH3), 4.00 (s, 3H, OCH3), 4.10 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H,
olefinic-H), 6.60 (s, 1H, furane-H), 7.18 (s, 1H, furane-H), 7.18 (m, 2H, arom-H), 7.80
(d, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C18H13NO5S: C
60.85, H 3.66, N 3.94, S 9.02%. Found: C 60.84, H 3.69, N 3.93, S, 9.01%.
(2E)-3-(4-Chlorophenyl)-1-(6-hydroxy-4-methoxy-1-benzofuran-5-
◦
yl)prop-2-ene-1-thione (8e). Yield 99%, mp 120 C, yellow crystals (from MeOH).
MS, m/z: (374.5, 24.2%). IR (KBr), ν (cm−1): 3405 (OH), 3290–3285 (CH, aromatic),
2995–2880 (CH, aliphatic), 1345 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s,
3H, OCH3), 4.00 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H, olefinic-H), 7.60

THIONATION OF CHALCONE BY LAWESSON’S REAGENT
809
(s, 1H, furane-H), 7.18 (s, 1H, furane-H), 7.90 (m, 2H, arom-H), 8.18 (m, 2H, arom-H),
12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C19H15ClO4S: C 60.88, H 4.03, S,
8.54%. Found: C 60.88, H 4.00, S 8.55%.
(2E)-1-(6-Hydroxy-4,7-dimethoxy-1-benzof◦uran-5-yl)-3-(4-methoxyphe
nyl)prop-2-ene-1-thione (8f). Yield 98%, mp 100 C, yellow crystals (from MeOH).
MS, m/z: (370, 30.2%). IR (KBr), ν (cm−1): 3415 (OH), 3290–3280 (CH, aromatic),
2885–2870 (CH, aliphatic), 1345 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.50 (s,
3H, OCH3), 3.98 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H, olefinic-H), 6.60
(s, 1H, furane-H), 7.18 (s, 1H, furane-H), 6.80 (m, 2H, arom-H), 7.40 (m, 2H, arom-H),
12.00 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C20H18O5S: C 64.86, H 4.86, S
8.66%. Found: C 64.85, H 4.90, S 8.64%.
1-(6-Hydroxy-4,7-dimethoxy-1-benzofuran-5-yl)-3-(4-dimethoxyphenyl)
◦
prop-2-ene-1-thione (8g). Yield 98%, mp 115 C, orange crystals (from benzene).
MS, m/z: (401, 60.3%). IR (KBr), ν (cm−1): 3425 (OH), 3285 (CH, aromatic), 2885 (CH,
aliphatic), 1345 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s, 3H, OCH3), 3.98
(s, 3H, OCH3), 4.03 (s, 3H, OCH3), 4.14 (s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s,
1H, olefinic-H), 6.60 (s, 1H, furane-H), 7.18 (s, 1H, furane-H), 7.18 (m, 2H, arom-H), 7.80
(m, 2H, arom-H), 12.60 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C21H21O6S: C
62.84, H 5.23, S 7.98%. Found: C 62.83, H 5.27, S, 7.99%.
1-(6-Hydroxy-4,7-dimethoxy-1-benzofuran-5-yl)-3-(4-nitrophenyl)prop-
◦
2-ene-1-thione (8h). Yield 98%, mp 175 C, yellow crystals (from MeOH/benzene).
MS, m/z: (385, 21.0%). IR (KBr), ν (cm−1): 3435 (OH), 3290 (CH, aromatic), 2885 (CH,
aliphatic), 1351 (C S). 1H NMR (270 MHz, CDCl3, TMS): δ = 3.88 (s, 3H, OCH3), 4.00
(s, 3H, OCH3), 6.60 (s, 1H, olefinic-H), 7.20 (s, 1H, olefinic-H), 6.60 (s, 1H, furane-H),
7.18 (s, 1H, furane-H), 7.18 (m, 2H, arom-H), 7.80 (m, 2H, arom-H), 12.66 (s, 1H, OH,
D2O exchangeable). Anal. calcd. for C19H15NO6S: C 59.22, H 3.89, N 3.63, S 8.31%.
Found: C 59.21, H 3.92, N, 3.63, S 8.32%.
Synthesis of Compounds 13a–h: General Procedure
To a suspension of aurones 12a–h (0.01 mol) in dry toluene (30 mL) LR (0.005 mol)
was added. The reaction mixture was refluxed for 22 h. The progress of the reaction was
monitored by TLC. After completion of the reaction, the reaction mixture was filtered and
the solvent was evaporated in vacuo. The resulting residue was applied to a column by
packing slurry of silica gel in n-hexane. Ethyl acetate/petroleum ether (4: 6, v/v) was used
as an eluent.
2-(3-Chloro-benzylidene)-4-methoxy-benzo[1,2-b;5,4-b]difurane-3-
◦
thione (13a). Yield 60%, mp 198 C, yellow crystals. MS, m/z: (342.5, 18.15%). IR
(KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic), 1345 (C S). H
1
NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H, OCH3), 7.80 (s,
1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (d, 2H, arom-H), 7.50
(d, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C18H11ClO3S: C
63.07, H 3.21, S 9.34%. Found: C 63.30, H 3.23, S 9.35%.
4-Methoxy-2-(3-methoxy-benzylidene)-benzo[1,2-b;5,4-b]difurane-3-
thione (13b). Yield 70%, mp 210 ◦C, yellow crystals. MS, m/z: (338, 30.2%). IR (KBr),
1
ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic), 1345(C S). H NMR
(270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H, OCH3), 7.80 (s, 1H,
CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m, 2H, arom-H), 7.50 (m,

810
E. ELHEFNY
2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C19H14O4S: C 67.45,
H 4.14, S 9.48%. Found: C 67.44, H 4.17, S 9.46%.
2-(3,5-Dimethoxy-benzylidene)-4-methoxy-benzo[1,2-b;5,4-bꢀ]difurane-
◦
3-thione (13c). Yield 70%, mp 200 C, brown crystals. MS, m/z: (368, 60.1%). IR
(KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH-aliphatic), 1345 (C S). H
1
NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H, OCH3), 7.80 (s,
1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m, 2H, arom-H), 7.50
(m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C20H16O5S: C
65.22, H 4.34, S 8.70%. Found: C 65.20, H 4.38, S 8.69%.
4-Methoxy-2-(3-methoxy-5-nitro-benzylidene)-benzo[1,2-b;5,4-
bꢀ]difurane-3-thione (13d). Yield 80%, mp 290 ◦C, brownish crystals. MS, m/z:
(353, 24.14%). IR (KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH-aliphatic),
1
1345 (C S). H NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s,
3H, OCH3), 7.80 (s, 1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m,
2H, arom-H), 7.50 (m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd.
for C18H11NO5S: C 61.19, H 3.11, N 3.96, S 9.07%. Found: C 61.18, H 3.12, N 3.96, S
9.06%.
2-(3-Chloro-benzylidene)-4,◦8-dimethoxy-benzo[1,2-b;5,4-bꢀ]difurane-3-
thione (13e). Yield 60%, mp 215 C, brown crystals. MS, m/z: (372.5, 10.12%). IR
1
(KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic), 1345 (C S). H
NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H, OCH3), 7.80 (s,
1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m, 2H, arom-H), 7.50
(m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C19H13ClO4S: C
61.20, H 3.49, S 8.60%. Found: C 60.21, H, 3.48, S, 8.59%.
4,8-Dimethoxy-2-(3-methoxy◦-benzylidene)-benzo[1,2-b;5,4-bꢀ]difurane-
3-thione (13f). Yield 65%, mp 165 C, orange crystals. MS, m/z: (368, 17.44%). IR
1
(KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic), 1345 (C S). H
NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H, OCH3), 7.80 (s,
1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m, 2H, arom-H), 7.50
(m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd. for C20H16O5S: C
65.22, H 4.35, S 8.69%. Found: C, 65.20, H 3.38, S 8.70%.
2-(3,5-Dimethoxy-benzylidene)-4,8-dimethoxy-benzo-[1,2-b;5,4-
bꢀ]difurane-3-thione (13g). Yield 60%, mp 205 ◦C, brownish crystals. MS, m/z:
(398, 55.6%). IR (KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic),
1
1345 (C S). H NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21
(s, 3H, OCH3), 7.80 (s, 1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H),
6.70 (m, 2H, arom-H), 7.50 (m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable).
Anal. calcd. for C21H18O6S: C 63.32, H 4.52, S 8.04%. Found: C 63.30, H 4.55,
S 8.05%.
4,8-Dimethoxy-2-(3-methoxy-5-nitro-ben◦zylidene)-benzo[1,2-b;5,4-
bꢀ]difurane-3-thione (13h). Yield 75%, mp 315 C, orange crystals. MS, m/z: (382,
60.1%). IR (KBr), ν (cm−1): 3415 (OH), 3295 (CH), 3280–3270 (CH, aliphatic), 1345
1
(C S). H NMR (270 MHz, DMSO-d6, TMS): δ = 4.16 (s, 3H, OCH3), 4.21 (s, 3H,
OCH3), 7.80 (s, 1H, CHR), 6.80 (m, 1H, furane-H), 7.30 (m, 1H, furane-H), 6.70 (m,
2H, arom-H), 7.50 (m, 2H, arom-H), 12.66 (s, 1H, OH, D2O exchangeable). Anal. calcd.
for C19H12NO6S: C 59.53, H 3.39, N 3.65, S 8.36%. Found: C 59.52, H 3.42, N 3.65, S
8.38%.

THIONATION OF CHALCONE BY LAWESSON’S REAGENT
811
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