Selenium-Nitrogen Bond Cleavage in Selenazole Ring System with Grignard Reagent: A Convenient Synthesis of Unsymmetrically Substituted Selenides

Article abstract of DOI:10.1080/00397910902730994

High reactivity of the selenenamide bond in selenazoles toward nucleophiles can be exploited for synthesis of other organoselenium compounds. It has been found that benzisoselenazol-3(2H)-ones and related selenaheterocycles with an Se-N moiety treated with Grignard reagent gave unsymmetrical aryl-aryl and aryl-alkyl selenides in moderate to good yields. This reaction has a synthetic value because it is highly selective and can be realized under mild conditions.

Full text of DOI:10.1080/00397910902730994

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Selenium–Nitrogen Bond
Cleavage in Selenazole Ring
System with Grignard Reagent:
A Convenient Synthesis of
Unsymmetrically Substituted
Selenides
Rafał Lisiak a & Jacek Młochowski a
a Department of Organic Chemistry , Faculty of
Chemistry, Wrocław University of Technology ,
Wrocław, Poland
Published online: 03 Aug 2009.
To cite this article: Rafał Lisiak & Jacek Młochowski (2009) Selenium–Nitrogen Bond
Cleavage in Selenazole Ring System with Grignard Reagent: A Convenient Synthesis of
Unsymmetrically Substituted Selenides, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 39:17, 3141-3155,
DOI: 10.1080/00397910902730994
To link to this article: http://dx.doi.org/10.1080/00397910902730994
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Synthetic Communications1, 39: 3141–3155, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902730994
Selenium–Nitrogen Bond Cleavage in Selenazole
Ring System with Grignard Reagent:
A Convenient Synthesis of Unsymmetrically
Substituted Selenides
Rafał Lisiak and Jacek Młochowski
Department of Organic Chemistry, Faculty of Chemistry,
Wrocław University of Technology, Wrocław, Poland
Abstract: High reactivity of the selenenamide bond in selenazoles toward
nucleophiles can be exploited for synthesis of other organoselenium compounds.
It has been found that benzisoselenazol-3(2H)-ones and related selenaheterocycles
with an Se-N moiety treated with Grignard reagent gave unsymmetrical aryl-aryl
and aryl-alkyl selenides in moderate to good yields. This reaction has a synthetic
value because it is highly selective and can be realized under mild conditions.
Keywords: Grignard reagents, heterocycles, selenenamides, selenides
The selenenamides with endocyclic selenium–nitrogen moiety, such as
benzisoselenazol-3(2H)-ones 1, 1,3,2-benzothiaselenazoles 1,1-dioxides
2, and 1,3,2-benzodiselenazoles 3, are heterocyclic compounds of rising
interest. They have been reported as catalysts for hydroperoxide oxida-
tion of various organic functional groups, biological response modifiers,
gluthathione peroxidase mimetics, and promising anti-inflammatory
drugs.[1–3] The published papers generally have been devoted to synthesis
of these heterocyclic systems, but only a few of them were focused on
reactivity of the selenazole ring, although it has been postulated that
their biological action and chemical properties are connected with the
Received December 3, 2008.
Address correspondence to Rafał Lisiak, Department of Organic Chemistry,
´
Faculty of Chemistry, Wrocław University of Technology, Wybrzeze Wyspianskiego
˙
27, 50-370 Wrocław, Poland. E-mail: rafal.lisiak@pwr.wroc.pl
3141

3142
R. Lisiak and J. Młochowski
reactivity of selenenamide bond. As reported earlier, this bond was easily
cleaved by treatment with nucleophilic reducing agents such as hydrazine,
triphenylphosphine, and thiols.[4,5] The reactions with the carbon nucleo-
philes have been limited only to the treatment of 2-phenylbenzisoselenazol-
3(2H)-one (ebselen) with buthyllithium to give 2-carbamoylphenylbutyl
selenide.[6]
On the other hand, we focus our attention on diorganyl selenides
because they are an important class of compounds employed as
substrates and reagents in organic synthesis. Mainly, they are used for
preparation of alkenes,[7] enones,[8] and epoxides[9] as well as aldehydes
and ketones,[10] catalytic asymmetric imidation to selenimides,[11] and
for synthesis of other organoselenium compounds.[12–14] Therefore, many
methods of synthesis of selenides have been reported, but most of them
involve multistep procedures or they require severe conditions and
reagents of low stability.[15] During past years, the novel, mild procedures
leading to selenides (e.g., the cross coupling reaction between diphenyl
diselenides and alkyl halides promoted by equimolar amount of metallic
lanthanum) were reported as alternative, one-pot syntheses of unsym-
metric aryl-alkyl selenides.[16] Also, catalytic amounts of bimetallic
zinc–indium(III) salts have been used to generate selenolate anions from
diorganyl diselenides instead of lanthanum.[17] Preparation of selenides
can be also carried out from diaryl diselenides and alkyl- and arylboronic
acid using copper catalyst.[18] It noteworthy that all these methods
employed diselenides as starting materials.
In this work, we report the reactions of benzisoselenazol-3(2H)-ones
and their selenaheterocyclic analogs (Figure 1) with various alkyl- and
arylmagnesium bromides as carbon nucleophiles. All the substrates used
have a selenenamide moiety and other functional groups such as carbonyl
group, sulfonyl group, and another selenium atom built in the heterocyc-
lic ring. We found that interaction of nucleophilic carbon atom of
Grignard reagent with a electrophilic center localized on a selenium atom
Figure 1.

Synthesis of Unsymmetrically Substituted Selenides
3143
Figure 2.
in selenenamides results in cleavage of Se-N bond and furnishes the
corresponding diaryl or aryl-alkyl selenides 4–6 (Figure 2).
The key substrates, benzisoselenazol-3(2H)-ones 1, were obtained
from anthranilic acid in a four-step synthesis, the same way as reported
earlier.[4,19] 1,3,2-Benzodiselenazoles 3 were prepared from o-diiodoben-
zene by selenenylation with lithium diselenide in hexamethylphosphora-
mide (HMPA) to poly(bis-1,2-phenylene) diselenide, which was converted
into bis-1,2-(bromoseleno)benzene by treatment with bromine. Reaction
of bis-1,2-(bromoseleno)benzene with aliphatic amines yields the corre-
sponding 1,3,2-benzodiselenazoles 3.[20]
The synthesis of 1,3,2-benzothiaselenazoles-1,1-dioxides 2 starting
from o-sulfanilic acid in a seven-step process has been elaborated in
our laboratory earlier.[21] In this work, we simplified the procedure
and elaborated a new, one-pot method based on ortholithation of easily
available benzenosulfonamides and reaction of 2-lithioderivatives with
elementary selenium. After selenenylation, the formed intermediate
was oxidatively cyclized with copper(II) bromide (Scheme 1). 1,3,2-
Benzothiaselenazoles-1,1-dioxides 2 were isolated chromatographically
in 40–50% yield. The residue was a tarry mixture of several compounds.
Scheme 1. Synthesis of 1,3,2-benzothiaselenazoles 2.

3144
R. Lisiak and J. Młochowski
Scheme 2. Reaction of benzisoselenazol-3(2H)-ones 1.
Nevertheless, the synthesis is limited only to N-alkyl-1,3,2-
benzothiaselenazoles 1,1-dioxides. When N-phenylbenzenosulfonamide
was a substrate, ring closure did not occur, and 2,20-diselenobis(N-
phenylbenzenosulfonamide) 7 was the only product.
The model substrates taken for the reaction of selenenamide group
with Grignard reagents were two benzisoselenazol-3(2H)-ones: 2-
substituted with phenyl 1a and n-propyl 1b, two 2-alkyl-1,3,2-benzothia-
selenazoles 1,1-dioxides 2a (R1 ¼ n-propyl) and 2b (R1 ¼ t-butyl), and two
2-alkyl-1,3,2-benzodiselenazoles 3a (R1 ¼ n-propyl) and 3b (R1 ¼ t-butyl).
The Grignard reagents were prepared in the usual way from commercially
available alkyl and aryl bromides such as bromobenzene, 3-bromoanisol,
n-butyl bromide, and cyclohexyl bromide.
In the beginning, the reactions of 1 were carried out with equimolar
amount of Grignard reagent (Scheme 2, Table 1, data given in brackets),
but the products were accompanied by substantial amounts (about 40%)
of starting benzizoselenazol-3(2H)-ones. The best results were obtained
when alkyl- or arylmagnesium bromide was taken in 50% excess. Yields
of pure selenides 4 were greater for all starting substrates. Only selenide
Table 1. Reaction of benzisoselenazol-3(2H)-ones 1 with alkyl or arylmagnesium
bromides
Substrate 1
R1
C6H5
R2
Product 4
Yield (%)
a
(CH2)3CH3
C6H5
c-Hex
3-CH3OC6H4
(CH2)3CH3
C6H5
a
b
c
d
e
f
90 (63)a
86 (55)
56 (40)
70 (49)
89 (45)
78 (56)
81 (51)
86 (60)
b
(CH2)2CH3
c-Hex
3-CH3OC6H4
g
h
aThe yields of selenides 4 when substrates were used in 1:1 molar ratio.

Synthesis of Unsymmetrically Substituted Selenides
3145
Scheme 3. Reaction of 1,3,2-benzothiaselenazoles 1,1-dioxides 2.
4c was obtained in 56% yield, which could be caused by steric effect of two
bulky (phenyl and cyclohexyl) groups bearing the substrate and reagent.
Reactivity of the selenenamide bond in 1,3,2-benzothiaselenazoles
1,1-dioxides 2 to Grignard reagents was similar to reactivity of this bond
in benzisoselenazol-3(2H)-ones, and the reaction of 2 with alkyl- and aryl-
magnesium bromides resulted in previously unknown alkyl-aryl and aryl-aryl
selenides 5, formed in good yields (Scheme 3, Table 2). Lesser yield of selenide
5g was observed when the substrate and reagent have two bulky groups.
Similarly, 1,3,2-benzodiselenazoles 3 reacted with 2 equivalents of
organomagnesium compound, but the yields were less than in previous
cases (Table 3). The products were 1,2-di(alkylseleno)benzenes 6, a new
group of organoselenium compounds.
EXPERIMENTAL
General Methods
The reaction products were identified by their melting points (digital
melting-points apparatus Electrothermal IA 911000), their 1H NMR data
Table 2. Reaction of 1,3,2-benzothiaselenazoles-1,1-dioxides 2 with alkyl or aryl-
magnesium bromides
Substrate 2
R1
R2
Product 5
Yield [%]
a
(CH2)2CH3
(CH2)3CH3
C6H5
c-Hex
3-CH3OC6H4
(CH2)3CH3
C6H5
a
b
c
d
e
f
60
84
75
73
82
80
54
61
b
C(CH3)3
c-Hex
3-CH3OC6H4
g
h

3146
R. Lisiak and J. Młochowski
Scheme 4. Reaction of 1,3,2-benzodiselenazoles 3.
(d, ppm, CDCl3, tetramethylsilane (TMS), Bruker DRX 300-MHz
spectrometer), 77Se NMR data (d, ppm, dimethyl sulfoxide (DMSO)-d6,
Me2S as external 77Se standard, Bruker Avance 600-MHz spectrometer),
and infrared (IR) spectra (Perkin-Elmer 2000FT spectrometer.
Substrates, solvents, thin-layer chromatography (TLC) plates and silica
gel for column chromatography (70–230 mesh) were purchased from
Aldrich and Fluka.
Benzisoselenazol-3(2H)-ones 1 and 1,3,2-benzodiselenazoles 3 were
prepared according to known procedures.[4,19,20]
2-Alkyl-1,3,2-benzothiaselenazole-1,1-dioxide (2): General Procedure
N-Alkylbenzenesulfonamide (10 mmol) was dissolved in 50 ml of dry
tetra hydro furan (THF), and flask was immersed in an ice bath. After
cooling, 14.4 ml of n-butyllithium (23 mmol, 1.6 M hexane solution) was
added dropwise under nitrogen during 20 min, and the mixture was stir-
red for an additional 30 min. Then the selenium powder (0.79 g, 10 mmol)
was added to the clear, yellow mixture in one portion. The reaction
Table 3. Reaction of 1,3,2-benzodiselenazoles 3 with alkyl or
arylmagnesium bromides
Substrate 3
R1
R2
Product 6 Yield (%)
a
(CH2)2CH3
(CH2)3CH3
C6H5
c-Hex
3-CH3OC6H4
n-(CH2)3CH3
C6H5
a
b
c
d
e
f
54
57
68
58
50
58
49
62
b
C(CH3)3
c-Hex
3-CH3OC6H4
g
h

Synthesis of Unsymmetrically Substituted Selenides
3147
mixture was stirred until selenium dissolved. After 2 h, the resulting dark
redsolutionwascooledtoꢀ70ꢁC,andcopper(II)bromide(4.46 g,20 mmol)
was added. The mixture was kept at ꢀ70ꢁC for 1 h, then cooling bath was
removed and the flask was allowed to reach room temperature. Stirring
continued for an additional 2 h, and then the mixture was poured into
saturated aqueous solution of ammonium chloride (100 ml). The product
was extracted with dichloromethane (DCM 3 ꢂ 50 ml), dried (MgSO4),
and evaporated. From the residue, pure 2-alkyl-1,3,2-benzothaselenazole-
1,1-dioxide was isolated by column chromatography on silica gel using
DCM as an eluent, yielding a proper product, which was recrystallized
from carbon tetrachloride. 2-Propyl-1,3,2-benzothiaselenazole-1,1-dioxide
(2a): colorless crystals, yield 1.19 g (43%), mp 83–85ꢁC (ref. 84–86ꢁC[21]). 2-
tert-Butyl-1,3,2-benzothiaselenazole 1,1-dioxide (2b): colorless needles,
yield 1.6 g (55%), mp 110–112ꢁC (ref. 112–115ꢁC[21]).
Reaction of Selenenamides (1–3) with Grignard Reagents:
General Procedure
The solution of Grignard reagent (prepared from 1.5 mmol or 3.0 mmol
in case of 3 alkyl or aryl bromide and 1.5 mmol or 3.0 mmol in case of
3 magnesium turnings) in dry diethyl ether (5 ml) was cooled on an ice
bath and stirred. The solution of selenenamide (1.0 mmol) in dry diethyl
ether or tetrahydrofuran (THF, 10 ml) was added dropise. White precipi-
tation appeared immediately. The mixture was refluxed for 2 h and then
poured into water (30 ml). Selenide was extracted with methylene chloride
(3 ꢂ 10 ml), purified by column chromatography on silica gel using
CH2Cl2 for 4 and 5 or CH2Cl2–hexane 1:1 for 6 as an eluent, and
recrystallized from chloroform–hexane.
Data
2-(Butylselanyl)-N-phenylbenzamide (4a)
1
Yellow flakes, yield 0.28 g (90%), mp 93–94ꢁC; H NMR (300 MHz,
CDCl3): d 0.88 (t, 3H, J ¼ 7.2 Hz, CH3), 1.40 (sext, 2H, J ¼ 7.5 Hz,
CH2), 1.41–1.69 (m, 2H, CH2), 2.92 (t, 2H, J ¼ 7.4 Hz, CH2), 7.14
(t, 1H, J ¼ 6.2 Hz, ArH), 7.30–7.39 (m, 5H, ArH), 7.55–7.56 (m, 3H,
ArH), 8.21 (s, 1H, NH); 77Se NMR (600 MHz, CDCl3): d 301; IR
(KBr): 3313, 2961, 1598, 737 cmꢀ1. Anal. calcd. for C17H19NOSe
(332.30): C, 61.45; H, 5.76; N, 4.22. Found: C, 61.44; H, 5.70; N
4.16.

3148
R. Lisiak and J. Młochowski
2-(Phenylselanyl)-N-phenylbenzamide (4b)
Colorless flakes, yield 0.30 g (86%), mp 139–141ꢁC; 1H NMR (300 MHz,
CDCl3): d 7.17–7.20 (m, 2H, ArH), 7.36–7.40 (m, 6H, ArH), 7.60–7.64
(m, 5H, ArH), 7.67–7.70 (m, 1H, ArH), 7.85 (s, 1H, NH); 77Se NMR
(600 MHz, CDCl3): d 447; IR (KBr): 3326, 3045, 1641, 1522, 751 cmꢀ1
.
Anal. calcd. for C19H15NOSe (352.29): C, 64.78; H, 4.29; N, 3.98. Found:
C, 64.70; H, 4.28; N, 3.95.
2-(Cyclohexylselanyl)-N-phenylbenzamide (4c)
Yield 0.18 g (52%), colorless powder, mp 100–102 C; 1H NMR
(300 MHz, CDCl3): d 1.25–1.28 (m, 4H, 2CH2), 1.45–1.59 (m, 4H,
2CH2), 1.69–1.72 (m, 2H, CH2), 1.95–1.99 (m, 2H, CH2), 3.30–3.37 (m,
1H, CH), 7.15 (t, 1H, J ¼ 7.42 Hz, ArH), 7.35–7.40 (m, 4H, ArH), 7.66
(d, 3H, J ¼ 8.8 Hz, ArH), 7.83–7.86 (m, 1H, ArH), 8.69 (br, 1H, NH);
77Se NMR (600 MHz, CDCl3): d 452; IR (KBr): 3275, 2924, 1641,
1598, 1321, 749 cmꢀ1. Anal. calcd. for C19H21NOSe (358.34): C, 63.68;
H, 5.91; N, 3.91. Found: C, 63.61; H, 5.86; N, 3.88.
2-(3-Methoxyphenylselanyl)-N-phenylbenzamide (4d)
1
Colorless plates, yield 0.26 g (70%), mp 122–123 C; H NMR (300 MHz,
CDCl3): d 3.76 (s, 3H, CH3), 6.91 (dd, 1H, J ¼ 8.06 and J ¼ 2.57 Hz,
ArH), 7.13–7.16 (m, 3H, ArH), 7.22–7.29 (m, 5H, ArH), 7.37 (t, 2H,
J ¼ 7.93 Hz, ArH), 7.59 (d, 2H, J ¼ 7.82 Hz, ArH), 7.65–7.68 (m, 1H,
ArH), 7.82 (s, 1H, ArH); 77Se NMR (600 MHz, CDCl3): d 454; IR
(KBr): 3306, 3065, 2955, 1622, 1586, 1243, 745 cmꢀ1. Anal. calcd. for
C19H21NOSe (358.34): C, 63.68; H, 5.91; N, 3.91. Found: C, 63.64; H,
5.89; N, 3.88.
2-(Butylselanyl)-N-propylbenzamide (4e)
1
Colorless powder, yield 0.25 g (85%), mp 48–50ꢁC; H NMR (300 MHz,
CDCl3): d 0.91 (t, 3H, J ¼ 7.3 Hz, CH3), 1.00 (t, 3H, J ¼ 4.35 Hz, CH3),
1.44 (sext, 2H, J ¼ 7.2 Hz, CH2), 1.64 [m, 4H, (CH2)2], 2.89 (t, 2H,
J ¼ 7.6 Hz, CH2), 3.42 (d, 2H, J ¼ 7.2 Hz, CH2), 6.28 (br, 1H, NH),
7.24–7.28 (m, 2H, ArH), 7.45–7.50 (m, 2H, ArH); 77Se NMR
(600 MHz, CDCl3): d 301; IR (KBr): 3306, 2960, 1635, 1537, 739 cmꢀ1
.
Anal. calcd. for C14H21NOSe (298.28): C, 56.31; H, 7.10; N, 4.70. Found:
C, 56.24; H, 7.00; N, 4,75.

Synthesis of Unsymmetrically Substituted Selenides
3149
2-(Phenylselanyl)-N-propylbenzamide (4f)
Pale yellow needles, yield 0.25 g (85%), mp 78–79ꢁC; 1H NMR (300 MHz,
CDCl3): d 0.98 (t, 3H, J ¼ 7.4 Hz, CH3), 1.62 (sext. 2H, J ¼ 7.3 Hz, CH2),
3.40 (q, 2H, J ¼ 7.3 Hz, CH2), 6.34 (br, 1H, NH), 7.05–7.07 (m, 1H,
ArH), 7.12–7.15 (m, 2H, ArH), 7.34–7.36 (m, 3H, ArH), 7.48–7.50
(m, 1H, ArH), 7.61 (dd, 2H, J ¼ 5.4 and J ¼ 1.5 Hz, ArH); 77Se NMR
(600 MHz, CDCl3): d 449; IR (KBr): 3310, 2957, 1627, 1530, 744 cmꢀ1
.
Anal. calcd. for C16H17NOSe (318.27): C, 60.38; H, 5.38; N, 4.40. Found:
C, 60.40; H, 5.30; N, 4.35.
2-(Cyclohexylselanyl)-N-propylbenzamide (4g)
Light brown powder, yield 0.26 g (81%), mp 104–106ꢁC; 1H NMR
(300 MHz, CDCl3): d 1.02 (t, 3H, J ¼ 7.41 Hz, CH3), 1.25–1.39 (m, 2H,
CH2), 1.45–1.76 (m, 8H, CH2), 2.00 (dd, 2H, J ¼ 12.97 and J ¼ 2.26 Hz,
CH2), 3.33 (tt, 1H, J ¼ 10.63 and J ¼ 3.67 Hz, CH), 3.43 (dd, 2H,
J ¼ 13.28 and J ¼ 6.77 Hz, CH2), 6.59 (s, 1H, NH), 7.28–7.33 (m, 2H,
ArH), 7.59 (dd, 1H, J ¼ 5.89 and J ¼ 3.20, ArH), 7.63 (dd, 1H, J ¼ 5.54
and J ¼ 3.76 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 351; IR (KBr):
3277, 3078, 2926, 1627, 1549, 688 cmꢀ1. Anal. calcd. for C16H23NOSe
(324.32): C, 59.25; H, 7.15; N, 4.32. Found: C, 59.19; H, 7.12; N, 4.28.
2-(3-Methoxyphenylselanyl)-N-propylbenzamide (4h)
1
Brown powder, yield 0.30 g (86%), mp 119–120ꢁC. H NMR (300 MHz,
CDCl3): d 0.99 (t, 3H, J ¼ 7.41 Hz, CH3), 1.58–1.70 (m, 2H, CH2), 3.43
(t, 2H, J ¼ 7.14 Hz, CH2), 3.79 (s, 3H, OCH3), 6.12 (s, 1H, NH), 6.91
(ddd, 1H, J ¼ 8.09 and J ¼ 2.56 and J ¼ 1.23 Hz, ArH), 7.11–7.21
(m, 5H, ArH), 7.26 (t, 1H, J ¼ 3.93 Hz, ArH), 7.50 (dd, 1H, J ¼ 5.66
and J ¼ 3.43 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 436; IR
(KBr): 3310, 2958, 1629, 1535, 1249, 742 cmꢀ1. Anal. calcd. for
C17H19NO2Se (348.30): C, 58.62; H, 5.50; N, 4.02. Found: C, 58.57; H,
5.44; N, 3.99.
2-(Butylselanyl)-N-propylbenzenesulfonamide (5a)
Yellow oil, yield 0.20 g (60%). 1H NMR (300 MHz, CDCl3): d 0.90 (t, 3H,
J ¼ 7.41 Hz, CH3), 0.96 (t, 3H, J ¼ 7.37 Hz, CH3), 1.46–1.52 (m, 4H,
CH2), 1.74 (td, 2H, J ¼ 15.07 and J ¼ 7.49 Hz, CH2), 2.83 (dd, 2H,
J ¼ 13.56 and J ¼ 6.85 Hz, CH2), 3.04–3.06 (m, 2H, NCH2), 5.64 (t, 1H,

3150
R. Lisiak and J. Młochowski
J ¼ 6.02 Hz, NH), 7.37 (t, 1H, J ¼ 7.60 Hz, ArH), 7.47 (t, 1H, J ¼ 7.60 Hz,
ArH), 7.63 (d, 1H, J ¼ 7.74 Hz, ArH), 8.06 (d, 1H, J ¼ 7.83 Hz, ArH);
77Se NMR (600 MHz, CDCl3): d 305. IR (film): 3302, 3058, 2961,
2932, 1445, 1330, 1162, 757 cmꢀ1. Anal. calcd. for C13H21NO2SSe
(334.34): C, 46.70; H, 6.33; N, 4.19; S, 9.59. Found: C, 46.67; H, 6.33;
N, 4.18; S, 9.60.
2-(Phenylselanyl)-N-propylbenzenesulfonamide (5b)
Yellow oil, yield 0.29 g (84%). 1H NMR (300 MHz, CDCl3): d 0.93 (t, 3H,
J ¼ 7.40 Hz, CH3), 1.50–1.56 (m, 2H, CH2), 2.94 (dd, 2H, J ¼ 13.49 and
J ¼ 6.82 Hz, CH2), 5.48 (t, 1H, J ¼ 6.01 Hz, NH), 7.20 (dd, 1H, J ¼ 7.61
and J ¼ 1.37 Hz, ArH), 7.32 (ddd, 2H, J ¼ 9.67 and J ¼ 7.53 and J ¼
1.54 Hz, ArH), 7.42 (t, 2H, J ¼ 7.31 Hz, ArH), 7.46 (t, 1H, J ¼ 7.30 Hz,
ArH), 7.62 (d, 2H, J ¼ 6.94 Hz, ArH), 8.05 (dd, 1H, J ¼ 7.42 and
J ¼ 1.84 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 437; IR (film):
3310, 3058, 2965, 1443, 1327, 1161, 743 cmꢀ1. Anal. calcd. for
C15H17NO2SSe (354.33): C, 50.85; H, 4.84; N, 3.95; S, 9.05. Found: C,
50.81; H, 4.80; N, 3.91; S, 9.01.
2-(Cyclohexylselanyl)-N-propylbenzenesulfonamide (5c)
1
Pale yellow oil, yield 0.27 g (75%). H NMR (300 MHz, CDCl3): d 0.87
(t, 3H, J ¼ 7.32Hz, CH3), 1.26–1.42 (m, 4H, CH2), 1.45–1.58 (m, 6H,
CH2), 1.63–1.68 (m, 1H, CH), 2.03–2.08 (m, 2H, CH2), 2.79 (q, 2H,
J ¼ 6.79Hz, CH2), 5.74 (t, 1H, J ¼ 6.43Hz, NH), 7.41 (m, 2H, ArH),
7.68 (d, 1H, J ¼ 7.56Hz, ArH), 8.07 (dd, 1H, J ¼ 7.79 and J ¼ 1.60Hz,
ArH); 77Se NMR (600MHz, CDCl3): d 400; IR (film): 3303, 2931, 1444,
1330, 1162, 757 cmꢀ1. Anal. calcd. for C15H23NO2SSe (360.37): C, 49.99;
H, 6.43; N, 3.89; S, 8.90. Found: C, 49.89; H, 6.38; N, 3.87; S, 8.88.
2-(3-Methoxyphenylselanyl)-N-propylbenzenesulfonamide (5d)
1
Colorless oil, yield 0.28 g (73%). H NMR (300 MHz, CDCl3): d 0.90
(t, 3H, J ¼ 7.40 Hz, CH3), 1.43–1.55 (m, 2H, CH2), 2.91 (q, 2H,
J ¼ 6.70 Hz, CH2), 3.82 (s, 3H, OCH3), 5.45 (t, 1H, J ¼ 6.13 Hz, NH),
6.97 (dd, 1H, J ¼ 8.39 and J ¼ 2.75 Hz, ArH), 7.16 (dd, 2H, J ¼ 7.83
and J ¼ 0.98 Hz, ArH), 7.21–7.25 (m, 1H, ArH), 7.30 (ddd, 3H,
J ¼ 8.73 and J ¼ 7.68 and J ¼ 2.95 Hz, ArH), 8.02 (dd, 1H, J ¼ 5.87 and
J ¼ 3.44 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 442; IR (film):
3311, 3060, 2965, 1587, 1161, 733 cmꢀ1. Anal. calcd. for C16H19NO3SSe

Synthesis of Unsymmetrically Substituted Selenides
3151
(384.35): C, 50.00; H, 4.98; N, 3.64; S, 8.34. Found: C, 49.94; H, 4.96; N,
3.60; S, 8.30.
N-tert-Butyl-2-(butylselanyl)benzenesulfonamide (5e)
1
Colorless prisms, yield 0.27 g (82%), mp 81–82ꢁC. H NMR (300 MHz,
CDCl3): d 0.93 (t, 3H, J ¼ 7.4 Hz, CH3), 1.19 [s, 9H, C(CH3)3], 1.47 (q,
2H, J ¼ 7.4 Hz, CH2), 1.68–1.75 (m, 2H, CH2), 3.03 (t, 2H, J ¼ 7.6 Hz,
CH2), 5.63 (s, 1H, NH), 7.33 (t, 1H, J ¼ 1.22 Hz, ArH), 7.41 (t, 1H,
J ¼ 1.6 Hz, ArH), 7.57 (dd, 1H, J ¼ 6.6 and J ¼ 1.1 Hz, ArH), 8.06 (dd,
1H, J ¼ 6.1 and J ¼ 1.6 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d
306; IR (KBr): 3245, 2966, 1311, 1147, 753 cmꢀ1. Anal. calcd. for
C14H23NO2SSe (348.26): C, 48.27; H, 6.65; N, 4.02; S, 9.20. Found: C,
48.20; H, 6.59; N, 4.01; S, 9.18.
N-tert-Butyl-2-(phenylselanyl)benzenesulfonamide (5f)
Pale yellow prisms, yield 0.20 g (80%), mp 130–132ꢁC. 1H NMR
(300 MHz, CDCl3): d 1.25 [s, 9H, C(CH3)3], 5.49 (s, 1H, NH),
7.18–7.20 (m, 1H, ArH), 7.26–7.29 (m, 2H, ArH), 7.38–7.42 (m, 3H,
ArH), 7.60 (dd, 2H, J ¼ 5.9 and J ¼ 1.6 Hz, ArH), 8.04 (d, 2H, J ¼ 7 Hz,
ArH); 77Se NMR (600 MHz, CDCl3): d 437. IR (KBr): 3310, 2933, 1326,
1154, 761 cmꢀ1. Anal. calcd. for C16H19NO2SSe (368.35): C, 52.17; H,
5.20; N, 3.80; S, 8.70. Found: C, 52.10; H, 5,15; N, 3,78; S, 8.62.
N-tert-Butyl-2-(cyclohexylselanyl)benzenesulfonamide (5g)
Pale yellow needles, yield 0.20 g (54%), mp 125–127ꢁC. 1H NMR
(300 MHz, CDCl3): d 1.20 [s, 9H, C(CH3)3], 1.32–1.67 (m, 6H, CH2),
1.75–1.81 (m, 2H, CH2), 2.07 (dd, 2H, J ¼ 12.87 and J ¼ 2.63 Hz, CH2),
3.57 (tt, 1H, J ¼ 10.76 and J ¼ 3.70 Hz, CH), 5.75 (s, 1H, NH),
7.32–7.43 (m, 2H, ArH), 7.65 (dd, 1H, J ¼ 7.44 and J ¼ 1.55 Hz, ArH),
8.09 (dd, 1H, J ¼ 7.60 and J ¼ 1.78 Hz, ArH); 77Se NMR (600 MHz,
CDCl3): d 425; IR (KBr): 3309, 3052, 2933, 1447, 1326, 1154, 761 cmꢀ1
.
Anal. calcd. for C16H25NO2SSe (374.40): C, 51.33; H, 6.73; N, 3.74; S,
8.56. Found: C, 51.30; H, 6.69; N, 3.70; S, 8.56.
N-tert-Butyl-2-(3-methoxyphenylselanyl)benzenesulfonamide (5h)
Colorless prisms, yield 0.24 g (61%), mp 134–136ꢁC. 1H NMR (300 MHz,
CDCl3): d 1.24 [s, 9H, C(CH3)3], 3.80 (s, 3H, OCH3), 5.46 (s, 1H, NH),

3152
R. Lisiak and J. Młochowski
6.93–6.96 (m, 1H, ArH), 7.15 (d, 1H, J ¼ 1.57 Hz, ArH), 7.18–7.19 (m,
1H, ArH), 7.23 (t, 1H, J ¼ 2.0 Hz, ArH), 7.26–7.27 (m, 2H, ArH),
7.29–7.30 (m, 1H, ArH), 8.01–8.07 (m, 1H, ArH); 77Se NMR
(600 MHz, CDCl3): d 442; IR (KBr): 3441, 3278, 2967, 1591, 1312,
1147, 759 cmꢀ1. Anal. calcd. for C17H21NO3SSe (398.38): C, 51.25; H,
5.31; N, 3.52; S, 8.05. Found: C, 51.22; H, 5.28; N, 3.28; S, 8.06.
1,2-Bis(butylselanyl)benzene (6a, 6e)
Orange oil, yield 0.2 g (57%). 1H NMR (300 MHz, CDCl3): d 0.92 (t, 6H,
J ¼ 7.3 Hz, 2CH3), 1.45 (q, 4H, J ¼ 7.6 Hz, 2CH2), 1.66–7.76 (m, 4H,
2CH2), 2.87–2.98 (m, 4H, 2CH2), 7.08–7.16 (m, 2H, ArH), 7.49 (dd,
1H, J ¼ 5.8 and J ¼ 1.6 Hz, ArH), 7.61 (dd, 1H, J ¼ 7.7 and J ¼ 1.6 Hz,
ArH); 77Se NMR (600 MHz, CDCl3): d 284; IR (film): 3049, 2956,
2927, 1435, 745. Anal. calcd. for C14H22Se2 (348.24): C, 48.28; H, 6.37.
Found: C, 48.20; H, 6.20.
1,2-Bis(phenylselanyl)benzene (6b, 6f)
1
Yellow powder, yield 0.21 g (54%), mp 90–92ꢁC. H NMR (300 MHz,
CDCl3): d 7.06–7.17 (m, 4H, ArH), 7.25–7.27 (m, 4H, ArH), 7.32–7.34
(m, 1H, ArH), 7.37–7.40 (m, 2H, ArH), 7.47 (dd, 1H, J ¼ 5.8 and
J ¼ 1.6 Hz, ArH), 7.52 (m, 1H, ArH), 7.59 (dd, 1H, J ¼ 7.6 and
J ¼ 1.5 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 402; IR (KBr):
3057, 1433, 733 cmꢀ1. Anal. calcd. for C18H14Se2 (388.22): C, 55.69; H,
3.36. Found: C, 55.58; H, 3.33.
1,2-Bis(cyclohexylselanyl)benzene (6c, 6g)
1
Yellow oil, yield 0.27 g (68%). H NMR (300 MHz, CDCl3): d 1.24–1.43
(m, 6H, CH2), 1.57–1.65 (m, 6H, CH2), 1.77–1.79 (m, 4H, CH2),
2.04–2.10 (m, 4H, CH2), 1.32–1.34 (m, 2H, CH), 7.03–7.09 (m, 1H,
ArH), 7.13–7.16 (m, 1H, ArH), 7.52 (dd, 1H, J ¼ 7.44 and J ¼ 1.48 Hz,
ArH), 7.63 (dd, 1H, J ¼ 7.78 and J ¼ 1.42 Hz, ArH); 77Se NMR
(600 MHz, CDCl3): d 419; IR (film): 3048, 2927, 2850, 1446, 743 cmꢀ1
.
Anal. calcd. for C18H26Se2 (400.32): C, 54.01; H, 6.55. Found: C,
53.90; H, 6.49.
1,2-Bis(3-methoxyphenylselanyl)benzene (6d, 6h)
Yellow oil, yield 0.27 g (62%). 1H NMR (300 MHz, CDCl3): d 3.77 (s, 3H,
OCH3), 3.81 (s, 3H, OCH3), 6.82 (dd, 1H, J ¼ 8.22 and J ¼ 1.99 Hz,

Synthesis of Unsymmetrically Substituted Selenides
3153
ArH), 6.89 (dd, 1H, J ¼ 8.22 and J ¼ 2.00 Hz, ArH), 6.96 (d, 1H,
J ¼ 2.12 Hz, ArH), 6.99 (d, 1H, J ¼ 7.71 Hz, ArH), 7.13–7.16 (m, 2H,
ArH), 7.21 (t, 2H, J ¼ 8.04 Hz, ArH), 7.25–7.28 (m, 2H, ArH), 7.53
(dd, 1H, J ¼ 7.56 and J ¼ 1.29 Hz, ArH), 7.65 (dd, 1H, J ¼ 7.90 and
J ¼ 1.10 Hz, ArH); 77Se NMR (600 MHz, CDCl3): d 407. IR (film):
3050, 3000, 2934, 1562, 1435, 1038, 748 cmꢀ1. Anal. calcd. for
C20H18O2Se2 (448.28): C, 53.59; H, 4.05. Found: C, 53.48; H, 3.99.
ACKNOWLEDGMENTS
The work was supported by the Ministry of Science and Higher
Education (Grant 351788=20305).
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