The preparation of acylselenourea and selenocarbamate using isoselenocyanate

Article abstract of DOI:10.1080/10426500600862894

Acyl isoselenocyanates were prepared by a reaction of acyl chloride with KSeCN. The acyl isoselenocyanates formed in situ were ready for further reaction without concentration. N-Acyl selenoureas were obtained by a reaction of acyl isoselenocyanates with

Full text of DOI:10.1080/10426500600862894

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The Preparation of
Acylselenourea and
Selenocarbamate Using
Isoselenocyanate
Mamoru Koketsu a , Yusuke Yamamura b , Hiroshi
Aoki b & Hideharu Ishihara b
a Division of Instrumental Analysis, Life Science
Research Center , Gifu University , Gifu, Japan
b Department of Chemistry , Gifu University , Gifu,
Japan
Published online: 22 Nov 2006.
To cite this article: Mamoru Koketsu , Yusuke Yamamura , Hiroshi Aoki & Hideharu
Ishihara (2006) The Preparation of Acylselenourea and Selenocarbamate Using
Isoselenocyanate, Phosphorus, Sulfur, and Silicon and the Related Elements, 181:12,
2699-2708, DOI: 10.1080/10426500600862894
To link to this article: http://dx.doi.org/10.1080/10426500600862894
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Phosphorus, Sulfur, and Silicon, 181:2699–2708, 2006
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500600862894
The Preparation of Acylselenourea and Selenocarbamate
Using Isoselenocyanate
Mamoru Koketsu
Division of Instrumental Analysis, Life Science Research Center,
Gifu University, Gifu, Japan
Yusuke Yamamura
Hiroshi Aoki
Hideharu Ishihara
Department of Chemistry, Gifu University, Gifu, Japan
Acyl isoselenocyanates were prepared by a reaction of acyl chloride with KSeCN. The
acyl isoselenocyanates formed in situ were ready for further reaction without con-
centration. N-Acyl selenoureas were obtained by a reaction of acyl isoselenocyanates
with amines. The reaction of acyl isoselenocyanates with nucleophiles gave the cor-
responding selenocarbamate. All the compounds were well characterized by using
13
77
spectral data, such as C and Se NMR and X-ray diffraction.
Keywords Isoselenocyanate; selenourea; selenocarbamate
Acyl isoselenocyanates are useful intermediates for the preparation of
selenium-containing heterocycles.1 Acyl isoselenocyanates were pre-
pared by a reaction of acyl chloride 1 with potassium selenocyanate,
a method first investigated by Douglas.2 The acyl isoselenocyanates
were never isolated. It was assumed that a polymeric form was
present in equilibrium with the monomer that underwent the observed
reactions. A generation of the isoselenocyanates was confirmed by a re-
action with nucleophiles. Douglas reported a reaction of the isoseleno-
cyanates with amines in 1937. However, it included a limited number
of products and lacked modern technology data, such as 13C and 77Se
NMR and X-ray diffraction.3 Although many studies of isothiocyanates
Received November 17, 2005; accepted May 4, 2006.
This work was supported by a Grant in Aid for Science Research from the Ministry
of Education, Culture, Sports, Science and Technology of Japan (No. 17550099) to which
we are grateful.
Address correspondence to Mamoru Koketsu, Life Science Research Center, Gifu
University, Gifu, 501-1193 Japan. E-mail: koketsu@gifu-u.ac.jp
2699

2700
M. Koketsu et al.
have been reported,4 studies on isoselenocyanates have been limited.5
In the present study, we describe reactions of acyl isoselenocyanates
with amines or nucleophiles. The crystal structure of acylselenourea
was investigated.
RESULTS AND DISCUSSION
p-Toluoylisoselenocyanate was prepared by the reaction of p-toluoyl
chloride 1a with potassium selenocyanide in acetone in situ, to which
benzylamine 2a was added and stirred for 15 min. After the usual
workup, N-benzyl-Nꢀ-p-toluoylselenourea 3a was obtained quantita-
tively (Scheme 1). Various kinds of N-acylselenoureas were obtained
in moderate to high yields (Table I). Reactions with primary amines
(Table I, entries 1–8) and reactions with secondary amines (Table I, en-
tries 9–10) gave 3 in nearly the same yields. In the case of reactions
using aliphatic acyl chloride, i.e., methyl and butyl groups (Table I,
entries 5–6), though the product 3e and 3f was apparently confirmed
to be quantitatively formed in the reaction mixture from the result
of TLC monitoring, 3e and 3f were obtained in low yields due to de-
composition in the purification process. Typical spectroscopic proper-
ties of compounds 3 are summarized in Table I. The chemical shifts of
amide carbonyl carbon (C O) of compounds 3 in the 13C NMR spectra
are δ 165.3 2.14 (aroyl acyl group; Table I, entries 1–4 and 7–10) and
δ 175.2 5.87 (acetyl and pivaloyl groups; Table I, entries 5–6). We can
not distinguish between N-acylselenoureas 3a–3h obtained by the re-
actions with primary amines (δ180.5 0.99) and N-acylselenoureas 3i
and 3j obtained by the reactions with secondary amines (δ180.7 0.21)
from the differences of the chemical shifts of C Se in 13C NMR spec-
tra. 77Se NMR was used to find the difference between the previously
discussed compounds. Significant differences of the chemical shifts of
selenium between 3a–3h (δ337.9 12.2) and 3i and 3j (δ469.8 9.26)
were clear in the 77Se NMR spectra (Table I). 77Se NMR spectra are one
of the useful methods for structural determination.
The X-ray crystal structure of N-benzyl-Nꢀ-p-toluoylselenourea 3a
was studied. An ORTEP drawing, depicted in Figure 1, shows the molec-
ular structure of 3a. The crystal was built up of cetrosymmetric Se and
O
Se
O
O
KSeCN
R1R2NH (2)
R1
R
N
H
N
R2
Acetone
Acetone
R
Cl
R
N C Se
1
3
SCHEME 1

The Preparation of Acylselenourea and Selenocarbamate
2701
TABLE I The Preparation of N-Acylselenourea 3
C
Se
Yield (%)
C O
Entry
1
Product (3)
(3)
13C NMR 13C NMR 77Se NMR
O
Se
quant.
78
166.7
166.8
181.0
181.0
344.1
351.0
N
H
N
H
H3C
3a
O
Se
N
H
N
H
2
3b
O
Se
N
H
N
H
3
4
5
6
71
63
166.2
165.7
171.0
179.3
181.0
180.9
180.6
180.9
338.2
356.9
326.4
333.7
H3CO
3c
O
Se
N
H
N
H
Cl
3d
O
O
Se
H3C
N
H
N
H
tracea
19a
3e
3f
Se
But
N
H
N
H
O
O
Se
Se
N
H
N
H
7
quant.
71
166.5
166.8
161.7
162.1
178.1
180.4
180.8
180.5
320.9
331.6
463.2
476.3
H3C
3g
3h
N
H
N
H
8
H3C
O
Se
N
H
N
9
64
O3i
H3C
O
Se
N
H
N
10
quant.
H3C
3j
aA product was generated in a reaction mixture in situ quantitatively. However, it
decomposed in the process of purification.

2702
M. Koketsu et al.
FIGURE 1 An ORTEP diagram (50% thermal ellipsoids) of compound 3a.
6
˚
˚
H N bonded dimmers. The bond lengths of C1A N2A (1.393(4) A),
˚
˚
N2A C3A (1.381(4) A), C3A N4A (1.317(4) A), C1B N2B (1.377(4) A),
N2B C3B (1.386(4) A), and C3B N4B (1.328(4) A) in 3a also were
shorter than the usual value of 1.47 A. The sums of the three angles
˚
˚
7
˚
around the C1A, C3A, C1B, and C3B were 360.0◦. The arrangement
of O1, C1, N2, C3, Se1, and N4 atoms was almost planarowing to the
result of the double bond character of the C1 N2, N2 C3, and C3 N4
bonds. These results can be attributed to the delocalization of the lone-
pair electrons on N2 and N4 to the C1( O1) N2 C3( Se1) N4. De-
localization of the electron is consistent with an observation of an NH
proton in a low field (δ11.5 for 3a) in 1H NMR.
Next, we investigated the reaction of p-toluoyl isoselenocyanates
with nucleophiles. For example, an anhydrous acetone solution of
in situ generated p-toluoyl isoselenocyanate was added to a solu-
tion of BuSe (5.0 equiv), which was freshly prepared by a re-
action of BuSeLi with an ether solution of hydrochloric acid in

The Preparation of Acylselenourea and Selenocarbamate
2703
O
Se
O
O
BuEH
or
Se, BuLi
KSeCN
R
N
H
EBu
Acetone
R
Cl
R
N C Se
R = 4-CH3C6H4
E=O, S
Yield: 79% (4, O)
58% (5, S)
1a
61% (6, Se)
SCHEME 2
dry THF under an argon atmosphere. After workup, Se-butyl N-p-
toluoyldiselenocarbamate 6 was obtained as orange needle crystals in a
61% yield (Scheme 2). Reactions with butanol or butanethiol also gave
the corresponding O-butyl N-p-toluoylselenocarbamate 4 or S-butyl N-
p-toluoylselenothiocarbamate 5 in 79% or 58% yields, respectively. Pre-
viously, the synthesis of Te-alkyl selenotellurocabamate was reported.8
Present reactions with nucleophiles also proceeded similarly.
Acylselenoureas are used as useful precursors for the synthesis
of heterocycles and N-selenocarbamoyl benzimidoyl chloride.9 In this
study, various kinds of acylselenoureas were prepared by reactions of
acyl isoselenocyanates with amines. Also acyl isoselenocyanates were
reacted with nucleophiles to give the corresponding acyl selenocaba-
mate ester. The compounds were characterized by spectral data, such
as 13C and 77Se NMR and X-ray diffraction.
EXPERIMENTAL
General
77Se chemical shifts were expressed in ppm deshielded with respect to
neat Me2Se in CDCl3.
The Synthesis of N-benzyl-N’-p-toluselenourea 3a
To a solution of KSeCN (0.28 g, 2 mmol) in acetone (5 mL) was added
p-toluoyl chloride 1a (0.13 mL, 1 mmol) in acetone (5 mL). The reaction
mixture was stirred at 25◦C for 10 min under an argon atmosphere.
Benzylamine 2a (0.22 mL, 2 mmol) in acetone (5 mL) was added to the
mixture, and the mixture was stirred for 15 min. The reaction mixture
was extracted with diethyl ether and washed with water. The organic
layer was dried over sodium sulfate and evaporated to dryness. The
residue was purified by flash column chromatography on silica gel using
n-hexane:diethyl ether (5:1) as an eluent to give 3a (0.35 g, quant). M.p.:
111.2–111.5◦C, IR (KBr): 1669, 1503 cm−1, 1H NMR (500 MHz, CDCl3):
δ 2.43 (3H, s, CH3), 4.96 (2H, d, J= 5.2 Hz,CH2), 7.30–7.41 (4H, m, Ar),

2704
M. Koketsu et al.
7.72 (2H, d, J= 8.6 Hz, Ar), 9.37 (1H, br, NH), 11.5 (1H, br, NH), 13C
NMR (100 MHz, CDCl3): δ 21.6, 53.0, 127.5, 128.0, 128.1, 128.3, 128.9,
129.8, 135.5, 144.9, 166.7, 181.0,77Se NMR (75 MHz, CDCl3): δ 344.1,
MS (CI): m/z= 333 [M+ + H]. Anal. calcd. for C16H16N2OSe: C, 58.01;
H, 4.87; N, 8.46. Found: C, 58.14; H, 5.02; N, 8.09.
X-ray Crystallographic Data
Single crystals were grown from a diethyl ether-hexane Crystal system
˚
Orthorhombic; space group Pna21; T = 190(2) K; a = 19.0835(19) A,
3
˚
˚
˚
b = 6.2335(6) A, c = 24.888(2) A, V = 2960.6(5) A , Z = 8; Dcalc = 1.486
g cm−3; crystal size 0.24 × 0.11 × 0.11 mm; θ range for data collection
3.3 to 27.5◦, Limiting indices −24 ≤ h≤ 24, −6 ≤ k≤ 8, −32 ≤l ≤ 32;
reflections collected: 35037, independent reflections: 6764 refinement
method: full-matrix least-squares on F2, goodness of fit on F2: 1.072, fi-
nal R indices [I > 2σ(I)]R1 = 0.0384, wR2 = 0.0785, R indices (all data)
R1 = 0.0505, wR2 = 0.0835, largest diff. peak and hole 1.777 and −0.415
−3
◦
˚
˚
e. A ; selected bond lengths (A) and angles ( ), Se(1A) C(3A): 1.851(3),
C(1A) O(1A): 1.217(4), C(1A) N(2A): 1.393(4), C(1A) C(12A):
1.490(5), N(2A) C(3A): 1.381(4), C(3A) N(4A): 1.317(4), N(4A) C(5A):
1.460(4), C(5A) C(6A): 1.525(5), Se(1B) C(3B): 1.833(3), O(1B) C(1B):
1.220(4), C(1B) N(2B): 1.377(4), C(1B) C(12B): 1.493(5), N(2B)
C(3B): 1.386(4), C(3B) N(4B): 1.328(4), N(4B) C(5B): 1.469(5),
C(5B) C(6B): 1.516(5), O(1A) C(1A) N(2A): 121.7(3), O(1A) C(1A)
C(12A): 122.6(3), N(2A) C(1A) C(12A): 115.7(3), C(3A) N(2A) C(1A):
127.4(3), N(4A) C(3A) N(2A): 117.8(3),N(4A) C(3A) Se(1A): 124.9(2),
N(2A) C(3A) Se(1A): 117.3(2), C(3A) N(4A) C(5A): 124.8(3), O(1B)
C(1B) N(2B): 122.9(3), O(1B) C(1B) C(12B): 121.3(3), N(2B)
C(1B) C(12B): 115.8(3), C(1B) N(2B) C(3B): 127.9(3), N(4B)
C(3B) N(2B): 117.1(3), N(4B) C(3B) Se(1B): 125.5(3), N(2B) C(3B)
Se(1B): 117.4(3), C(3B) N(4B) C(5B): 123.5(3) for all data.6
N-Benzoyl-N’-benzylselenourea 3b
1
M.p.: 114.8−115.2◦C, IR (KBr): 1675, 1528 cm−1, H NMR (500 MHz,
CDCl3): δ 4.95 (2H, s, CH2), 7.30–7.43 (5H, m, Ar), 7.49 (2H, t,
J= 7.75 Hz, Ar), 7.61 (1H, t, J= 7.45 Hz, Ar), 7.82 (2H, d, J= 7.45 Hz,
Ar), 9.43 (1H, br, NH), 11.5 (1H, br, NH), 13C NMR (125 MHz, CDCl3):
δ 52.9, 127.4, 127.9, 128.0, 128.8, 129.1, 133.7,166.8, 181.0, 77Se NMR
(75 MHz, CDCl3): δ 351.0, MS (CI): m/z= 319 [M+ + H]. Anal. calcd. for
C15H14N2OSe: C, 56.79; H, 4.45; N, 8.83. Found: C, 57.22; H, 4.62; N,
8.47.

The Preparation of Acylselenourea and Selenocarbamate
2705
N-Anisoyl-N’-benzylselenourea 3c
1
M.p.: 136.5−137.1◦C, IR (KBr): 1600, 1500 cm−1, H NMR (500 MHz,
CDCl3): δ 3.88 (3H, s, CH3O Ph), 4.96 (2H, d, J= 5.2 Hz, CH2), 6.97 (2H,
d, J= 8.6 Hz, Ar), 7.30–7.42 (5H, m, Ar), 7.81 (2H, d, J= 8.6 Hz, Ar),
9.32 (1H, br, NH), 11.6 (1H, br, NH), 13C NMR (100 MHz, CDCl3): δ 53.0,
55.6, 114.4, 123.1, 127.9, 128.1, 128.8, 129.7, 135.5, 164.0, 166.2, 181.0,
77Se NMR (75 MHz, CDCl3): δ 338.2, MS (CI): m/z= 349 [M+ + H].
N-Benzyl-N’-(4-chlorobenzoyl)selenourea 3d
1
M.p.: 112.0−112.9◦C, IR (KBr):1674, 1560 cm−1, H NMR (500 MHz,
CDCl3): δ 4.95 (2H, d, J= 5.8 Hz, CH2), 7.32–7.40 (5H, m, Ar), 7.49
(2H, d, J= 8.6 Hz, Ar), 7.78 (2H, d, J= 8.6 Hz, Ar), 9.43 (1H, br, NH),
11.6 (1H, br, NH), 13C NMR (100 MHz, CDCl3): δ 53.0, 128.0, 128.2,
128.9, 129.5, 135.4, 140.4, 165.7, 180.9, 77Se NMR (75 MHz, CDCl3): δ
356.9, MS (CI): m/z= 351 [M+ + H].
N-Acetyl-N’-benzylselenourea 3e
1
IR (KBr): 1699, 1541 cm−1, H NMR (500 MHz, CDCl3): δ 2.15 (3H, s,
CH3), 4.91 (2H, d, J= 5.2 Hz, CH2), 7.32–7.39 (5H, m, Ar), 9.27 (1H, br,
NH), 11.3 (1H, br, NH), 13C NMR (125 MHz, CDCl3): δ 24.3, 52.6, 127.9,
128.1, 128.9, 135.4, 171.0, 180.6, 77Se NMR (95 MHz, CDCl3): δ 326.4,
MS (CI): m/z= 257 [M+ + H].
N-Benzyl-N’-pivaloylselenourea 3f
1
M.p.: 111.2−112.0◦C, IR (KBr): 1678, 1548 cm−1, H NMR (500 MHz,
CDCl3): δ 1.26 (9H, s, t-Bu), 4.88 (2H, d, J= 5.2 Hz, CH2), 7.30–7.37
(5H, m, Ar), 8.81 (1H, br, NH), 11.4 (1H, br, NH), 13C NMR (125 MHz,
CDCl3): δ 26.8, 39.7, 53.0, 128.0, 128.1, 128.9, 135.3, 179.3, 180.9, 77Se
NMR (95 MHz, CDCl3): δ 333.7, MS (CI): m/z= 298 [M+ + H]. Anal.
calcd. for C13H18N2OSe: C, 52.53; H, 6.10; N, 9.42. Found: C, 52.36; H,
6.10; N, 8.92.
N-Cyclohexyl-N’-p-toluoylselenourea 3g
1
M.p.: 112.9−113.4◦C, IR (KBr):1666, 1521 cm−1, H NMR (500 MHz,
CDCl3): δ 1.23–1.80 (8H, m, CH), 2.05–2.19 (2H, m, CH), 2.43 (3H,
s, CH3), 4.34 (1H, m, CH), 7.29 (2H, d, J= 8.1 Hz, Ar), 7.73 (2H, d,
J= 8.1 Hz, Ar), 9.33 (1H, br, NH), 11.3 (1H, br, NH), 13C NMR (125

2706
M. Koketsu et al.
MHz, CDCl3): δ 21.4, 24.0, 25.0, 57.0, 127.3, 128.2, 129.5, 144.3, 166.5,
178.1,77Se NMR (95 MHz, CDCl3): δ 320.9, MS (CI): m/z= 325 [M+ + H].
N-Propyl-N’-p-toluselenourea 3h
M.p.: 88.5−90.0◦C, IR (KBr):1601, 1521 cm−1
,
1H NMR (500 MHz,
CDCl3): δ 1.04 (3H, t, J= 7.5 Hz, CH3), 1.78 (2H, six, J= 7.5 Hz, CH2),
2.43 (3H, s, CH3), 3.71 (2H, q, J= 6.9 Hz, CH3), 7.31 (2H, d, J= 8.6
Hz, Ar), 7.74 (2H, d, J= 8.1 Hz, Ar), 9.27 (1H, br, NH), 11.3 (1H, br,
NH), 13C NMR (125 MHz, CDCl3): δ 11.4, 21.5, 21.6, 50.6, 127.5, 128.4,
129.8, 144.7, 166.8, 180.4, 77Se NMR (95 MHz, CDCl3): δ 331.6, MS (CI):
m/z= 284 [M+ + H].
N-(Morpholinoselenocarbonyl)-p-toluamide 3i
1
M.p.: 155.3−155.9◦C, IR (KBr): 1666, 1525 cm−1, H NMR (500 MHz,
CDCl3): δ 2.43 (3H, s, CH3), 3.64 (2H, d, CH2), 3.80 (2H, t, J= 4.6 Hz,
CH2), 3.90 (2H, t, J= 4.9 Hz, CH2), 4.34 (2H, t, J= 4.6 Hz, CH2), 7.29
(2H, d, J= 8.0 Hz, Ar), 7.74 (2H, d, J= 8.6 Hz, Ar), 8.60 (1H, br, NH),
13C NMR (125 MHz, CDCl3): δ 21.6, 53.6, 55.3, 66.0, 66.2, 127.9, 129.2,
129.7, 144.2, 161.7, 180.8, 77Se NMR (95 MHz, CDCl3): δ 463.2, MS (CI):
m/z= 313 [M+ + H].
N,N-Diethyl-N’-p-toluselenourea 3j
1
M.p.: 126.0−127.6◦C, IR (KBr): 1641, 1527 cm−1, H NMR (500 MHz,
CDCl3): δ 1.31 (3H, t, J= 7.2 Hz, CH3), 1.42 (3H, t, J= 6.9 Hz, CH3),
2.43 (3H, s, CH3), 3.60 (2H, q, J= 6.9 Hz, CH2), 4.15 (2H, q, J= 6.9 Hz,
CH2), 7.29 (2H, d, J= 8.6 Hz, Ar), 7.74 (2H, d, J= 8.1 Hz, Ar), 8.50
(1H, br, NH), 13C NMR (125 MHz, CDCl3): δ 11.7, 12.8, 21.5, 48.4, 51.2,
127.9, 129.5, 129.6, 143.8, 162.1, 180.5, 77Se NMR (95 MHz, CDCl3): δ
476.3, MS (CI): m/z= 298 [M+ + H].
O-Butyl-N-p-toluselenocarbamate 4
To a solution of KSeCN (0.22 g, 1.3 mmol) in acetone (5 mL) was
added p-toluoyl chloride (0.13 mL, 1 mmol) in acetone (5 mL), and the
reaction mixture was stirred at 25◦C for 90 min under an argon atmo-
sphere. n-Butyl alcohol (0.46 mL, 5 mmol) was added to the mixture,
and the mixture was refluxed under for 24 h. The reaction mixture
was extracted with diethyl ether and washed with water. The organic
layer was dried over sodium sulfate and evaporated to dryness. The
residue was purified by flash column chromatography on silica gel us-
ing n-hexane:dichloromethane (1:1) as an eluent to give 4 (0.24 g, 79%).

The Preparation of Acylselenourea and Selenocarbamate
2707
M.p.: 62−63◦C, IR (KBr): 3167, 1686 cm−1, 1H NMR (270 MHz, CDCl3):
δ 0.98 (3H, t, J= 7.4 Hz, CH3), 1.52 (2H, six, J= 7.4 Hz, CH2), 1.85
(2H, quintet, J= 7.4 Hz, CH2), 2.42 (3H, s, CH3), 4.72 (2H, q, J= 7.4
Hz, CH2), 7.30 (2H, d, J= 8.2 Hz, Ar), 7.75 (2H, d, J= 8.2 Hz, Ar), 9.69
(1H, br, NH), 13C NMR (68 MHz, CDCl3): δ 13.6, 19.0, 21.6, 30.2, 78.0,
127.9, 129.7, 144.3, 161.4, 196.3.
S-Butyl-N-p-toluselenothiocarbamate 5
M.p.: 62−63◦C, IR (KBr): 3182, 1696 cm−1, 1H NMR (270 MHz, CDCl3):
δ 0.98 (3H, t, J= 7.3 Hz, CH3), 1.52 (2H, six, J= 7.4 Hz, CH2), 1.82 (2H,
quintet, J= 7.4 Hz, CH2), 2.43 (3H, s, CH3), 3.34 (2H, q, J= 7.4 Hz,
CH2), 7.32 (2H, d, J= 8.4 Hz, Ar), 7.81 (2H, d, J= 8.4 Hz, Ar), 10.6
(1H, br, NH), 13C NMR (68 MHz, CDCl3): δ 13.7, 21.7, 22.3, 29.1, 41.7,
127.8–144.6, 163.1, 207.7, Anal. calcd. for C13H17NOSSe: C, 49.67; H,
5.45. Found: C, 49.37; H, 5.58.
Se-Butyl-N-p-toludiselenocarbamate 6
To a solution of selenium (0.39 g, 5 mmol) in dry THF (5 mL) was
added 1.67 M solution of n-BuLi in n-hexane (3 mL, 5 mmol) at 0◦C
under an argon atmosphere, and the mixture stirred for 15 min. After
the mixture was cooled to −78◦C, 1M of HCl solution in diethyl ether
(6.5 mL, 6.5 mmol) was added, and the reaction mixture was stirred
at −78◦C for 15 min. To the resulting solution of n-BuSe the p-toluoyl
isoselenocyanate suspension (1 mmol) was added at −78◦C, and it was
stirred for 1 h. After the reaction mixture was warmed to 25◦C and
stirred at the same temperature for 1.5 h. The reaction mixture was
extracted with diethyl ether and washed with water. The organic layer
was dried over sodium sulfate and evaporated to dryness. The residue
was purified by flash column chromatography on silica gel using n-
hexane:dichloromethane (1:1) as an eluent to give 6 (0.22 g, 61%). M.p.:
1
73−75◦C, IR (KBr): 3134, 1693 cm−1, H NMR (270 MHz, CDCl3): δ
0.98 (3H, t, J= 7.4 Hz, CH3), 1.51 (2H, six, J= 7.4 Hz, CH2), 1.85 (2H,
quintet, J= 7.4 Hz, CH2), 2.44 (3H, s, CH3), 3.32 (2H, q, J= 7.4 Hz,
CH2), 7.33 (2H, d, J= 8.3 Hz, Ar), 7.83 (2H, d, J= 8.3 Hz, Ar), 10.96
(1H, br, NH), 13C NMR (68 MHz, CDCl3): δ 13.7, 21.7, 23.4, 29.7, 37.0,
127.8, 128.4, 130.0, 144.7, 163.8, 206.1, Anal. Calcd for C13H17NOSe2:
C, 43.21; H, 4.71. Found: C, 43.23; H, 4.67.
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