Facile method for conversion of 2-(Chloroseleno)benzoyl chloride into 2-substituted 3-hydroxybenzo[b]selenophenes

Article abstract of DOI:10.1080/00397910902898627

The easily accessible 2-(chloroseleno)benzoyl chloride has broad application in the synthesis of benzizoselenazol-3(2H)-ones and benzo[b]selenophen-3(2H)-ones. Treatment of 2-acylbenzo[b]selenophen-3(2H)-ones with nitrogen nucleophiles such as hydrazines

Full text of DOI:10.1080/00397910902898627

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Facile Method for Conversion
of 2-(Chloroseleno)benzoyl
Chloride into 2-Substituted 3-
Hydroxybenzo[b]selenophenes
Rafał Lisiak a & Jacek Młochowski a
a Department of Organic Chemistry, Faculty of
Chemistry, Wrocław University of Technology,
Wrocław, Poland
Version of record first published: 29 Oct 2009.
To cite this article: Rafał Lisiak & Jacek Młochowski (2009): Facile Method
for Conversion of 2-(Chloroseleno)benzoyl Chloride into 2-Substituted 3-
Hydroxybenzo[b]selenophenes, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 39:23, 4271-4281
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Synthetic Communications1, 39: 4271–4281, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902898627
Facile Method for Conversion of
2-(Chloroseleno)benzoyl Chloride into
2-Substituted 3-Hydroxybenzo[b]selenophenes
Rafał Lisiak and Jacek Młochowski
Department of Organic Chemistry, Faculty of Chemistry, Wrocław
University of Technology, Wrocław, Poland
Abstract: The easily accessible 2-(chloroseleno)benzoyl chloride has broad
application in the synthesis of benzizoselenazol-3(2H)-ones and benzo[b]
selenophen-3(2H)-ones. Treatment of 2-acylbenzo[b]selenophen-3(2H)-ones with
nitrogen nucleophiles such as hydrazines and hydroxylamine resulted in forma-
tion of 2-substituted 3-hydroxybenzo[b]selenophenes in 72–98% yield.
Keywords: Benzo[b]selenophenes, 2-(chloroseleno)benzoyl chloride, hydrazines,
selenaheterocycles
During the past decade, a growing interest in the methodology of the
synthesis of selenaheterocycles has been observed.[1] Some of them (par-
ticularly those having a selenenamide moiety) play an important role in
medicinal biology as biological response modifiers, gluthathione peroxi-
dase mimetics, and promising anti-inflammatory agents.[2] On the other
hand, they can be used as oxygen-transfer catalysts for hydroperoxide
oxidation of various organic functional groups.[1–4] We focus our atten-
tion on the selenophenes and their benzologs (e.g., benzoselenophenes)
because of their growing importance in material engineering as stable
organic semiconductors for high-performance, field-effect transis-
tors.[3,5,6] Although the benzo[b]selenophene moiety so far has not been
Received January 13, 2009.
Address correspondence to Rafał Lisiak, Department of Organic Chemistry,
´
Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspians-
˙
kiego 27, 50-370 Wrocław, Poland. E-mail: rafal.lisiak@pwr.wroc.pl
4271

4272
R. Lisiak and J. Młochowski
detected in natural products, they are considered bioisosteric with
benzene, thiophene, and pyrrole [e.g., 2-amino-3-(benzo[b]selenophen-3-
yl)propionic acid of the analog of the proteinogenic amino acid trypto-
phan].[7] The biological activity of benzo[b]selenophenes and their syn-
thetic applications have been presented in literature.[8] In comparison
with other selenaheterocycles, the works devoted to the synthesis of ben-
zo[b]selenophenes are limited to a few published papers.[9] The oldest
reported methods involved higher temperatures and gaseous reagents
such as acetylene, action of potassium hexacyanoferrate(III), on o-seleno-
cinnamic acids, or reaction of selenium dioxide with styrene in the pre-
sence of chromic oxide on aluminium oxide.[10] The yields of
benzo[b]selenophenes were usually poor. Reaction of selenophenols with
bromoacetaldehyde dimethyl acetal and oxidative cyclization of the
formed selenides with phosphorous pentoxide could lead to benzo[b]sele-
nophenes substituted in only the benzene ring.[11] As reagents for pre-
paration of benzo[b]selenophenes with more than 50% yield, the a,b-
unsaturated aldehydes can be used in thermal gas-phase reaction with
diorganyl diselenides.[10] 2,3-Disubstituted benzo[b]selenophenes have
been obtained by cyclization of 1-(1-alkynyl)-2-(methylseleno)arenes by
treatment with electrophiles such as bromine, N-bromosuccinimide
(NBS), and benzeneselenenyl chloride.[12]
First, we focused our attention on the synthesis of a new class of
selenium-containing heterocycles 2 and 4 based on the 2,3-dihydroben-
zo[b]selenophene system. For this purpose, we needed the substrates
bearing the 1,3-diketone moiety, which would give the pyrazole ring on
treatment with hydrazines. In a previous paper, we reported the reactions
of 2-(chloroseleno)benzoyl chloride 5 with C-H acids 6 having an acti-
vated methylene group with two hydrogen atoms leading to
benzo[b]selenophen-3(2H)-ones formation.[13,14] We expected that
2,2-disubstituted benzo[b]selenophen-3(2H)-ones 1 with acyl groups as
one of substituents present in the a-position would behave typically as
1,3-diketones and should form products with three condensed rings, 2,
when treated with hydrazines. Neither expected tricyclic products 2,4
nor dioxime of 1,3-diketone 3 (when hydroxylamine was a reagent) have
been isolated from the reaction mixture (Scheme 1).
On the other hand, spontaneous deacylation was observed earlier for
some of 2,2-diacyl benzo[b]selenophen-3(2H)-ones, especially in case of
acetylacetone derivatives, which could be explained by their hydrolyses
during isolation.[13] In other cases, the 2,2-disubstituted benzo[b]
selenophen-3(2H)-ones 1 remained stable. In the present study, we found
that deacylation of 2,2-disubstituted benzo[b]selenophen-3(2H)-ones 1
occured readily during treatment with hydrazines, regardless of the kind
of substituent, R1 and R2. We suggest the unstable hydrazone 8 is an

Synthesis of 3-Hydroxybenzo[b]selenophenes
4273
Scheme 1. The expected products of reaction 1 with hydrazine or hydroxylamine.
Scheme 2. A plausible mechanism of 2-substituted 3-hydroxybenzo[b]seleno-
phenes formation.
intermediate formed in the first stage of the reaction. The 2-substituted
3-hydroxybenzo[b]selenophenes 7 and corresponding hydrazones and
oximes were the only products (Scheme 2). The described protocols are
very useful for synthesis of the 2-substituted 3-hydroxybenzo[b]
selenophenes because the method is simple, more efficient, and general
in comparison with those reported earlier.
The results of the reaction of 2-(chloroseleno)benzoyl chloride 5 with
C-H acids 6 [i.e., benzoylacetonitrile, a-nitroacetophenone, ethyl benzoy-
lacetate, dibenzoylmethane, 1-phenyl-1,3-butanedione, 2,4-pentanedione,
diethyl (2-oxo-2-phenylethyl)phosphonate, and diethyl (2-oxopropyl)-
phosphonate] to give 2,2-disubstituted benzo[b]selenophen-3(2H)-ones 1
(Scheme 3) are presented in Table 1. The cyclization was carried out with
a 1:1 molar ration of 5 and 6; triethylamine was used in excess. Yields of
1a and 1d were satisfactory and comparable with Ref.[13] The poor yield
Scheme 3. Synthesis of benzo[b]selenophen-3(2H)-ones.

4274
R. Lisiak and J. Młochowski
Table 1. 2,2-Disubstituted benzo[b]selenophen-3(2H)-ones 1
1a
R1
R2
Yield (%)
a
b
c
d
e
f
CN
Ph
Ph
Ph
Ph
Ph
Ph
Me
Me
70
75
78
49
72
70
68
20
COOEt
COPh
COMe
NO2
PO3Et2
PO3Et2
COMe
g
h
aSome benzo[b]selenophen-3(2H)-ones 1 have been reported
earlier: 1a,[13] 1d,[14] and 1h.[13]
of compounds 1h is due to formation of macromolecular by-products,
which were difficult to characterize. The phosphonates 1f–g, nitro 1e,
and dibenzoyl 1c derivatives have not been reported thus far.
To prepare the 3-hydroxybenzo[b]selenophene 7, the mixture of 1
with phenyl- or methylhydrazine (or hydroxylamine hydrochloride with
the presence of triethylamine) was heated under reflux in ethanol for 3 h.
All used substrates were easily converted into benzo[b]selenophenes 7,
and yields did not depend on the N-nucleophile used (Scheme 4, Table 2).
Scheme 4. Synthesis of 3-hydroxybenzo[b]selenophenes.

Synthesis of 3-Hydroxybenzo[b]selenophenes
Table 2. 3-Hydroxybenzo[b]selenophenes 7
4275
Benzo[b]
Benzo[b]
Yieldb
(%) of 7 (%) of 7 (%) of 7
Yieldc
Yieldd
selenophenone 1 selenophenea 7
R1
a
b
c
d
e
f
a
b
c
d
e
f
CN
76
85
87
72
79
94
98
98
81
83
86
80
84
90
96
97
77
79
78
77
80
91
89
93
COOEt
COPh
COMe
NO2
PO3Et2
PO3Et2
COMe
g
h
f
d
aSome benzo[b]selenophenes 7 have been reported earlier: 7b[13] (yield 59%),
7c[13] (yield 28%), and 7d[13,14] (yield 58%).
bYields of 7 with MeNHNH2 as reagent.
cYields of 7 with PhNHNH2 as reagent.
dYields of 7 with NH2OH as reagent.
When position 2 in benzo[b]selenophen-3(2H)-one was occupied by
two different acyl groups (e.g., benzoyl and acetyl, 1d), only one product
of the reaction more resistant to elimination of substituent (7d,
R1 ¼ COMe) in the 2-position was observed. The easier leaving group
(COPh) was eliminated in the form of hydrazone (or oxime).
3-Hydroxybenzo[b]selenophene 7f was hydrolyzed to phosphonic
acid 7g. For this purpose, the solution of 7f in dry dichloromethane
was treated with an excess of trimethylbromosilane (Scheme 5). As a
result, we obtained 3-hydroxybenzo[b]selenophen-2-ylphosphonic acid
7g, which was stable in organic solvents but in the presence of water
slowly decomposed to elementary selenium.
The carbonyl groups of selenophen-3(2H)-one ring of 1 shows a
strong absorption band above 1715 cmꢀ1 in the IR spectra characteristic
for ring strain cycloalkanones. Acyl groups at position 2 absorb below
1700 cmꢀ1. In the IR spectra of compounds 7, broad bands of the
hydroxyl group are localized at 3142–3479 cmꢀ1, which suggests the
intramolecular hydrogen bond stabilizing the enol form.
Scheme 5. Synthesis of 3-hydroxybenzo[b]selenophen-2-ylphosphonic acid.

4276
R. Lisiak and J. Młochowski
In the 77Se NMR spectra of 7, the chemical shift of selenium nuclei
depends on the character of the substituent present in the position 2.
The resonance signal of cyano derivative 7a is observed at d ¼ 487 ppm,
whereas the chemical shift of acetyl derivative 7d is d ¼ 406 ppm. In all
phosphonate derivatives (1f–g, 7f–g), the resonance signal of 77Se nuclei
appears as a doublet (J ¼ 20–50 Hz) because of the coupling of selenium
and phosphorous nuclei.
EXPERIMENTAL
General Methods
The reaction products were identified by their melting points (Digital
Melting Points Apparatus Electrothermal IA 911000), by analysis of their
1H and 31P NMR data [(d, ppm, CDCl3 or dimethylsulfoxide (DMSO)-d6,
tetramethylsilane (TMS), H3PO4, Bruker DRX 300-MHz spectrometer)],
77Se NMR data (d, ppm, CDCl3 or DMSO-d6, Me2Se as external 77Se
standard, Bruker Avance 600-MHz spectrometer), and by analysis of IR
spectra (Perkin-Elmer 2000FT spectrometer). Substrates, solvents,
thin-layer chromatography (TLC) plates, and silica gel for column chro-
matography (70–230 mesh) were purchased from Aldrich and Fluka.
2-(Chloroseleno)benzoyl chloride 5 was prepared from anthranilic
acid according to the known procedure.[15,16]
Synthesis of 2,2-Disubstituted Benzo[b]selenazol-3(2H)-ones (1)
A solution of compound 2 (1 mmol) and triethylamine (2.8 mmol) in dry
ethyl acetate (30 ml) was cooled in an ice bath while 2-(chloroseleno)ben-
zoyl chloride 5 (0.25 g, 1 mmol) dissolved in dry ethyl acetate (20 ml) was
added dropwise. After the addition was completed, the mixture was
allowed to reach room temperature. Stirring was continued for an addi-
tional 24 h, and the precipitate was filtered. The filtrate was concentrated,
and the product was isolated from the residue by crystallization from
ethanol (for 1a–e) or column chromatography on silica gel using
dichloromethane–hexane 1:1 (for 1h) or ethyl acetate (for 1f–g) as eluent.
Data
2-Benzoyl-3-oxo-2,3-dihydrobenzo[b]selenophene-2-carbonitrile (1a)
Colorless crystals, yield 0.22 g (70%), mp 138–139ꢁC (140–142ꢁC[13]).

Synthesis of 3-Hydroxybenzo[b]selenophenes
4277
Ethyl 2-Benzoyl-3-oxo-2,3-dihydrobenzo[b]selenophene-2-carboxylate
(1b)
1
Yellow needles, yield 0.28 g (75%), mp 110–112ꢁC; H NMR (300 MHz,
CDCl3): d, 1.17 (t, 3H, J ¼ 7.12 Hz, CH3), 4.29 (q, 2H, J ¼ 7.10 Hz, CH2),
7.36 (t, 1H, J ¼ 7.44 Hz, ArH), 7.42–7.50 (m, 3H, ArH), 7.55–7.62 (m,
2H, ArH), 7.85 (dt, 3H, J ¼ 8.69 Hz and J ¼ 1.12 Hz, ArH); 77Se NMR
(600 MHz, CDCl3): d, 469; IR (KBr): 3063, 2981, 1736, 1699, 1675,
1671, 1233, 766 cmꢀ1. Anal. calcd. for C18H14O4Se (373.26): C, 57.92;
H, 3.78. Found: C, 57.90; H, 3.73.
2,2-Dibenzoylbenzo[b]selenophen-3(2H)-one (1c)
1
Yellow crystals, yield 0.32 g (78%), mp 143–145ꢁC; H NMR (300 MHz,
CDCl3): d, 7.34–7.43 (m, 5H, ArH), 7.47–7.53 (m, 3H, ArH), 7.63 (dt,
1H, J ¼ 8.05 Hz and J ¼ 7.91 Hz and J ¼ 1.32 Hz, ArH), 7.81–7.84 (m,
4H, ArH), 7.91–7.94 (m, 1H, ArH); 77Se NMR (600 MHz, CDCl3): d,
471; IR (KBr): 3069, 3027, 1715, 1661, 1444, 1224, 687 cmꢀ1. Anal. calcd.
for C22H14O3Se (405.30): C, 65.19; H, 3.48. Found: C, 65.13, H, 3.49.
2-Acetyl-2-benzoylbenzo[b]selenophen-3(2H)-one (1d)
Orange needles, yield 0.17 g (49%), mp 158–162ꢁC (oil[13]).
2-Benzoyl-2-nitrobenzo[b]selenophen-3(2H)-one (1e)
1
Yellow prisms, yield 0.25 g (72%), mp 174–176ꢁC; H NMR (300 MHz,
CDCl3): d, 7.41 (dt, 1H, J ¼ 7.52 Hz and J ¼ 0.97 Hz, ArH), 7.55 (t,
3H, J ¼ 8.03 Hz, ArH), 6.65–7.71 (m, 2H, ArH), 7.94 (dd, 1H, J ¼ 7.69 Hz
and J ¼ 1.35 Hz, ArH), 8.13 (dd, 2H, J ¼ 8.40 Hz and J ¼ 1.29 Hz, ArH);
77Se NMR (600 MHz, CDCl3): d, 409; IR (KBr): 3068, 1758, 1697, 1236,
1008, 697 cmꢀ1. Anal. calcd. for C15H9NO4Se (346.20): C, 52.04; H, 2.62;
N, 4.05. Found: C, 51.94; H, 2.56; N, 4,00.
Diethyl 2-Benzoyl-3-oxo-2,3-dihydrobenzo[b]selenophen-
2-ylphosphonate (1f)
1
Colorless crystals, yield 0.30 g (70%), mp 75–80ꢁC; H NMR (300 MHz,
CDCl3): d, 0.99 (t, 3H, J ¼ 7.07 Hz, CH3), 1.24 (t, 3H, J ¼ 7.08 Hz, CH3),
4.05–4.12 (m, 2H, CH2), 4.24–4.54 (m, 2H, CH2), 7.21 (dd, 2H,
J ¼ 8.35 Hz and J ¼ 7.52 Hz, ArH), 7.34 (t, 1H, J ¼ 7.41 Hz, ArH),

4278
R. Lisiak and J. Młochowski
7.39–7.41 (m, 1H, ArH), 7.53 (d, 1H, J ¼ 7.75 Hz, ArH), 7.56–7.59 (m,
1H, ArH), 7.61 (dd, 2H, J ¼ 8.49 Hz and J ¼ 1.16 Hz, ArH), 7.83 (dd,
1H, J ¼ 7.76 Hz and J ¼ 0.70 Hz, ArH); 31P NMR (300 MHz, CDCl3):
d, 14.6; 77Se NMR (600 MHz, CDCl3): d, 447 (d, J ¼ 20.30 Hz); IR
(KBr): 3095, 2979, 1715, 1686, 1662, 1238, 1010, 776 cmꢀ1. Anal. calcd.
for C19H9O5PSe (437.28): C, 52.19; H, 4.38. Found: C, 52,08; H, 4.30.
Diethyl 2-Acetyl-3-oxo-2,3-dihydrobenzo[b]selenophen-2-
ylphosphonate (1g)
1
Waxy solid, yield 0.25 g (68%); H NMR (300 MHz, CDCl3): d, 1.20 (t,
3H, J ¼ 7.06 Hz, CH3), 1.34 (t, 3H, J ¼ 7.08 Hz, CH3), 2.42 (s, 3H,
COCH3), 4.16–4.34 (m, 4H, 2CH2), 7.34 (ddd, 1H, J ¼ 8.01 Hz and
J ¼ 6.92 Hz and J ¼ 1.24 Hz, ArH), 7.53 (d, 1H, J ¼ 7.35 Hz, ArH),
7.56–7.62 (m, 1H, ArH), 7.84 (dd, 1H, J ¼ 7.80 Hz and J ¼ 0.60 Hz,
ArH); 31P NMR (300 MHz, CDCl3): d, 14.6; 77Se NMR (600 MHz,
CDCl3): d, 463 (d, J ¼ 51.0 Hz); IR (film): 3069, 2984, 1715, 1688,
1256, 1019, 791 cmꢀ1. Anal. calcd. for C14H17O5PSe (375.22): C, 44.81;
H, 4.57. Found: C, 44.77; H, 4.51.
2,2-Diacetylbenzo[b]selenophen-3(2H)-one (1h)
Orange solid, yield 0.06 g (20%), mp 106–110ꢁC (109–111ꢁC[14]).
Synthesis of 2-Substituted 3-Hydroxybenzo[b]selenophenes (7)
2,2-Disubstituted benzo[b]selenazol-3(2H)-one 1 (1 mmol) was dissolved
in warm ethanol (40 ml) and corresponding alkyl- or arylhydrazine
(1 mmol) or hydroxylamine hydrochloride (1 mmol) was added in one
portion. When hydroxylamine hydrochloride was used, addition of
triethylamine (1.1 mmol) was needed. The mixture was refluxed for 3 h.
After cooling, the hydrazones 5 crystallized. Then the solvent was evapo-
rated, and the product was isolated by column chromatography on silica
gel (DCM was an eluent for 7a–e and 7g, ethyl acetate for 7f).
Data
3-Hydroxybenzo[b]selenophene-2-carbonitrile (7a)
1
Colorless crystals, yield 0.17–0.18 g (76–81%), mp 147–148ꢁC; H NMR
(300 MHz, DMSO-d6): d, 7.58 (quin., 2H, J ¼ 7.10 Hz and J ¼ 1.08 Hz,

Synthesis of 3-Hydroxybenzo[b]selenophenes
4279
ArH), 8.05 (dd, 1H, J ¼ 8.10 Hz and J ¼ 1.24 Hz, ArH), 8.17 (dd, 1H,
J ¼ 7.80 Hz and J ¼ 1.17 Hz, ArH), 12.12 (s, 1H, OH); 77Se NMR
(600 MHz, DMSO-d6): d, 487; IR (KBr): 3142, 2205, 1268, 768 cmꢀ1
.
Anal. calcd. for C9H5NOSe (222.10): C, 48.67; H, 2.27; N, 6.31. Found:
C, 48.64; H, 2.22; N, 6.25.
Ethyl 3-Hydroxybenzo[b]selenophene-2-carboxylate (7b)
Yellow crystals, yield 0.21–0.23 g (79–85%), mp 86–87ꢁC (87–88ꢁC[13]).
2-Benzoyl-3-hydroxybenzo[b]selenophene (7c)
Yellow needles, yield 0.23–0.26 g (78–87%), mp 107–109ꢁC (109–
111ꢁC[13]).
2-Acetyl-3-hydroxybenzo[b]selenophene (7d)
Violet prisms, yield 0.17–0.19 g (72–80%), mp 76–77ꢁC (76–78ꢁC[14]).
3-Hydroxy-2-nitrobenzo[b]selenophene (7e)
1
Yellow crystals, yield 0.19–0.20 g (79–84%), mp 155–157ꢁC; H NMR
(300 MHz, CDCl3): d, 7.33–7.38 (m, 1H, ArH), 7.53 (ddd, 1H,
J ¼ 7.83 Hz and J ¼ 1.05 and J ¼ 0.57 Hz, ArH), 7.62 (ddd, 1H,
J ¼ 7.82 Hz and J ¼ 7.23 Hz and J ¼ 1.45 Hz, ArH), 7.89 (ddd,
1H, J ¼ 7.69 Hz and J ¼ 1.42 Hz and J ¼ 0.55 Hz, ArH), 9.99 (s, 1H,
OH); 77Se NMR (600 MHz, CDCl3): d, 435; IR (KBr): 3147, 3087,
2984, 1687, 1284, 997, 732 cmꢀ1. Anal. calcd. for C8H5NO3Se (242.09):
C, 39.69; H, 2.08; N, 5.79. Found: C, 39.54; H, 1.98; N, 5.58.
Diethyl 3-Hydroxybenzo[b]selenophen-2-ylphosphonate (7f)
Colorless oil, yield 0.29–0.33 g (89–98%); 1H NMR (300 MHz,
DMSO-d6): d, 1.35 (t, 6H, J ¼ 7.06 Hz, 2CH3), 4.08–4.20 (m, 4H,
2CH2), 7.41–7.47 (m, 2H, ArH), 7.82 (dd, 1H, J ¼ 6.18 Hz and
J ¼ 2.84 Hz, ArH), 7.96 (dd, 1H, J ¼ 6.24 Hz and J ¼ 3.06 Hz, ArH),
10.46 (s, 1H, OH); 31P NMR (300 MHz, DMSO-d6): d, 14.6; 77Se
NMR (600 MHz, CDCl3): d, 465 (d, J ¼ 45.5 Hz); IR (film): 3389, 3062,
2984, 1574, 1526, 1020, 731 cmꢀ1. Anal. calcd. for C12H15O4PSe
(333.18): C, 43.26; H, 4.54. Found: C, 43.14; H, 4.39.

4280
R. Lisiak and J. Młochowski
3-Hydroxybenzo[b]selenophen-2-ylphosphonic Acid (7g)
Diethyl 3-hydroxybenzo[b]selenophen-2-ylphosphonate 7f (0.33 g, 1 mmol)
was dissolved in dry DCM (10 ml) and trimethylbromosilane (0.6 g,
0.52ml, 4 mmol) was added under a slow stream of nitrogen. The mixture
was stirred for 24h, and then the solvent was evaporated. The silyl esters
were decomposed by treatment with methanol (10 ml). After evaporation
the solvent, the product was isolated from the residue by crystallization
from ethanol. Yield 0.22g (78%), pale orange crystals, mp 158–160ꢁC;
1H NMR (300MHz, DMSO-d6): d, 7.45 (dd, 2H, J ¼ 6.03Hz and
J ¼ 3.19Hz, ArH), 7.79–7.82 (m, 1H, ArH), 8.04–8.07 (m, 1H, ArH),
11.11 (s, 1H, OH); 31P NMR (300MHz, DMSO-d6): d, 13.2; 77Se NMR
(600MHz, CDCl3): d, 462 (d, J ¼ 51.23 Hz); IR (KBr): 3394, 3083, 2935,
1651, 735 cmꢀ1. Anal. calcd. for C8H7O4PSe (277.07): C, 34.68; H, 2.55.
Found: C, 34.59; H, 2.44.
ACKNOWLEDGMENT
The work was supported by the Ministry of Science and Higher Education
(Grant 351788=20305).
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3,5-diaryl-1,2,4-thiadiazoles and 3,5-diaryl-1,2,4-selenadiazoles. J. Het. Chem.
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