Synthesis and Reactivity of 2-Acyl-1,3-selenazoles

Article abstract of DOI:10.1055/s-2003-44348

2-Acyl-1,3-selenazoles were prepared in two steps from α- bromoketones and seleno amides. The base mediated fragmentation of these compounds afforded 2-unsubstituted 1,3-selenazoles. The reaction of 2-acyl-1,3-selenazoles with hydroxylamine hydrochloride

Full text of DOI:10.1055/s-2003-44348

PAPER
97
Synthesis and Reactivity of 2-Acyl-1,3-selenazoles
S
ynthesis andRea
a
c
tivity of
2
r
Acyl-1,3
l
-selena
h
zoles einz Geisler,* Andreas Künzler, Harald Below, Ehrenfried Bulka, Wolf-Diethard Pfeiffer, Peter Langer*
Institut für Chemie und Biochemie, Ernst-Moritz-Arndt-Universität Greifswald, Soldmannstr. 16, 17487 Greifswald, Germany
Fax +49(3834)864346; E-mail: peter.langer@uni-greifswald.de
Received 8 July 2003; revised 7 October 2003
Reflux
Ar1
Ar1
O
Ar2
Abstract: 2-Acyl-1,3-selenazoles were prepared in two steps from
-bromoketones and seleno amides. The base mediated fragmenta-
tion of these compounds afforded 2-unsubstituted 1,3-selenazoles.
The reaction of 2-acyl-1,3-selenazoles with hydroxylamine hydro-
chloride afforded oximes which were transformed into 2-carba-
moyl-1,3-selenazoles by a regioselective Beckmann rearrangement.
H2N
EtOH
N
Ar2
+
_
_
H2O
HBr
R
Se
2a-e
Se
R
Br
1a-c
3a-m
Scheme 1 Synthesis of 2-arylmethyl-1,3-selenazoles 3a–m
Table 1 Products and Yields
Key words: cyclization, fragmentation, selenium heterocycles, re-
arrangement, 1,3-selenazoles
3
Ar2
Ar1
R
Yield Mp
(%)a [°C]b
1,3-Selenazoles are of pharmacological relevance, due to
their antibiotic and cancerostatic activity.1 A prominent
example is the antibiotically active C-glycosyl selenazole
selenazofurin.1a 1,3-Selenazoles have been mainly pre-
pared by application of the Hantzsch procedure.2,3 How-
ever, the scope of this approach is limited, since a number
of selenazole derivatives, such as 2-unsubstituted or 2-
acyl-1,3-selenazoles, can not be directly prepared. There-
fore, only a few 2-unsubstituted 1,3-selenazoles are
known to date and the methods available for their prepa-
ration have a number of drawbacks, such as low yields or
a limited preparative scope.4,5
a
b
c
d
e
f
C6H5
C6H5
H
91
77
100
88
88
60
71
73
67
78
86
86
81
99.5–100.0
100.0–101.0
C6H5
4-MeC6H4
4-BrC6H4
4-O2NC6H4
C6H5
H
C6H5
H
127.5–129.0
122.0–123.5
121.5–123.0
108.0–110.0
140.5–141.5
128.0–129.0
134.0–135.0
120.5
C6H5
H
C6H5
C6H5
H
4-ClC6H4
4-ClC6H4
4-ClC6H4
4-ClC6H4
4-O2NC6H4
4-O2NC6H4
4-O2NC6H4
4-O2NC6H4
C6H5
g
h
i
4-MeC6H4
4-BrC6H4
4-O2NC6H4
C6H5
H
H
In a preliminary communication, we have recently report-
ed two new and convenient methods for the synthesis of
2-unsubstituted 1,3-selenazoles. The first method relies
on the direct cyclisation of -bromoketones with seleno-
formamide. So far, only one selenazole has been prepared
by this approach. In fact, the cyclization seems to be high-
ly dependent on the substrate and further studies have to
be carried out. In addition, selenoformamide is very diffi-
cult to prepare in pure form and requires much experience.
Our second approach to 2-unsubstituted 1,3-selenazoles
relies on the fragmentation of 2-acyl-1,3-selenazoles.6
Herein, we wish to report full details of this method which
is more robust, but requires more synthetic steps. In addi-
tion, we wish to report other synthetic applications of 2-
acyl-1,3-selenazoles.7 This includes a new approach to 2-
carbamoyl-1,3-selenazoles which relies on the reaction of
2-acyl-1,3-selenazoles with hydroxylamine hydrochlo-
ride to give ketoximes. The latter underwent a regioselec-
tive Beckmann rearrangement upon treatment with
phosphorous pentachloride.
H
j
H
k
l
4-MeC6H4
4-BrC6H4
4-O2NC6H4
H
94.5
H
167.0–169.0
162.0–164.0
m
H
a Yields of isolated products.
b Uncorrected.
The cyclisation of -bromoacetophenone (1a) with sele-
nophenylacetic amide (2a), prepared from phenylacetoni-
trile and P2Se5,8 afforded 2-benzyl-4-phenyl-1,3-
selenazole (3a) in 99% yield (Scheme 1, Table 1). A vari-
ety of 2-arylmethyl-1,3-selenazoles 3a–m were prepared
in good to very good yields by cyclization of the -bro-
moketones 1a–c with seleno amides 2a–e.
K2Cr2O7, AcOH
Ar1
R
Ar1
R
or
N
Se
Ar2
N
Se
Ar2
SeO2, Dioxane
O
3a-m
4a-m
SYNTHESIS 2004, No. 1, pp 0097–0105
Advanced online publication: 19.11.2003
x
x
.
x
x
.2
0
0
3
Scheme 2 Synthesis of 2-acyl-1,3-selenazoles 4a–m
DOI: 10.1055/s-2003-44348; Art ID: T06503SS.pdf
© Georg Thieme Verlag Stuttgart · New York

98
K. Geisler et al.
PAPER
Table 2 Products and Yields
Ar1
R
Ar1
R
N
Ar2
NaOH
N
Se
A
Ar2
O _
4
a
Ar2
Ar1
R
Yield (%)a mp [°C]
Na+
Se
EtOH
H2O
O
HO
Ab
64
–
Bb
70
74
4
C6H5
C6H5
H
76.0–77.0
94.5–95.0
b
c
d
e
f
C6H5
4-MeC6H4
4-BrC6H4
4-O2NC6H4
C6H5
H
Ar1
R
Ar1
N
O
O
_
O
C6H5
H
60
76
70
45
79
50
62
53
42
57
82
80 143.5–145.0
70 192.0–193.5
N
+
_
Ar2
O
Na+
Se
R
Na+
Se
C6H5
H
(0%)
5a-e
C6H5
C6H5
H
–
135.5–136.5
Scheme 3 Synthesis of 2-unsubstituted 1,3-selenazoles 5a–e
Table 3 Products and Yields
4-ClC6H4
4-ClC6H4
4-ClC6H4
4-ClC6H4
C6H5
84 135.0–136.0
84 132.5–135.0
g
h
i
4-MeC6H4
4-BrC6H4
4-O2NC6H4
H
Educt 5
Ar1
R
Yield
(%)a
2-Hb
5-Hb
H
–
171.5–173.0
H
72 241.0
4a
4f
a
a
a
b
c
C6H5
H
84
60
84
90
83
71
77
10.16
10.16
10.16
10.15
10.15
10.23
10.13c
8.69
10.16
10.16
8.60
8.76
9.06
–
j
4-O2NC6H4 C6H5
H
72 151.0–153.0
83 187.0–189.0
60 211.0–213.0
58 258.0–260.0
C6H5
H
k
l
4-O2NC6H4 4-MeC6H4
4-O2NC6H4 4-BrC6H4
4-O2NC6H4 4-O2NC6H4
H
4j
C6H5
H
H
4b
4c
4d
4e
4-MeC6H4
4-BrC6H4
4-NO2C6H4
C6H5
H
m
H
H
a Yields of isolated products.
b A: K2Cr2O7, HOAc; B: SeO2, 1,4-dioxane.
d
e
H
C6H5
The oxidation of 3a with K2Cr2O7 in glacial HOAc (Meth-
od A) afforded 2-benzoyl-4-phenyl-1,3-selenazole (4a) in
64% yield. The yield could be improved by the use of
SeO2 in 1,4-dioxane (Method B).8 A variety of novel 2-
acyl-1,3-selenazoles 4a–m were successfully prepared by
oxidation of 3a–m (Scheme 2, Table 2). The application
of Method B gave generally better results than Method A
(except for 4d,e,m).
a Isolated yields.
b 1H NMR (DMSO-d6) [ppm].
c CDCl3: 9.86 ppm.
The fragmentation of the 2-acyl-1,3-selenazoles 4a,f,j
gave the 2-unsubstituted 1,3-selenazole 5a. The best
yields (84%) were obtained for the starting materials 4a
and 4j (Ar2 = C6H5, 4-O2NC6H4). The use of 4f (Ar2 = 4-
ClC6H4) was less efficient (60% yield). The substituents
Ar1 and R were also varied. The 2-unsubstituted 1,3-sel-
enazoles 5a–e were prepared in good yields from 2-ben-
zoyl-1,3-selenazoles 4a–e (Table 3). Low field
resonances in the range of = 10.13 (5e)–10.23 (5d) ppm
were observed for protons 2-H (DMSO-d6).
Treatment of an EtOH solution of 4a with NaOH (reflux)
afforded the 2-unsubstituted 1,3-selenazole 5a in 84%
yield (58% overall yield from 1a). In addition, benzoic
acid was isolated in stoichiometric amounts. Selenazole
5a was formed by attack of NaOH onto the carbonyl
group to give the tetrahedral intermediate A (Scheme 3)
which subsequently underwent a heterolytic fragmenta-
tion.9 The formation of 4-phenyl-1,3-selenazole-2-car-
boxylic acid was not observed. The regioselectivity can be
explained by stabilization of the negative charge in a 1,3-
selenazolyl carbanion (by interaction of the electrons with
the unoccupied selenium orbitals). The concentration,
The reaction of 2-acyl-1,3-selenazoles with carbon and ni-
trogen nucleophiles was studied next. The reaction of 4a
with dicyanomethane and thiosemicarbazide afforded the
functionalized 1,3-selenazoles 6a and 6b (Figure 1) in
67% and 68% yields, respectively.
temperature, reaction time and solvent proved to be im- The reaction of 2-acyl-1,3-selenazoles 4a,f,j with hy-
droxyamine hydrochloride gave the novel ketoximes 7a–
c in good yields (Scheme 4). Treatment of 7a,b with PCl5
portant parameters during the optimization of the frag-
mentation. No conversion was observed when the
concentration of NaOH was too low or when the reaction
was carried out at room temperature. The system NaOH–
EtOH gave optimal results. Other solvents proved to be
less effective. A minimum reaction time of 1 h was re-
quired in order to isolate 5a in good yield. However, ex-
tended reaction times led to significant decomposition.
Ph
Ph
N
N
Ph
Ph
CN
Se
Se
N
NH
NC
6a
NH2
S
6b
Figure 1
Synthesis 2004, No. 1, 97–105 © Thieme Stuttgart · New York

PAPER
Synthesis and Reactivity of 2-Acyl-1,3-selenazoles
99
MS (70 eV): m/z = 298 (68) [M+], 182 (100), 102 (93), 91 (22), 89
(12), 77 (7), 66 (6), 32 (12), 28 (61).
resulted in a Beckmann rearrangement to give the 2-car-
bamoyl-1,3-selenazoles 8a,b. The rearrangement pro-
ceeded with very good regioselectivity by exclusive Anal. Calcd for C16H13NSe (298.25): C, 64.44; H, 4.39; N, 4.70.
Found: C, 6.40; H, 4.20; N, 4.79.
migration of the aryl rather than the selenazolyl group.
The formation of the regioisomeric product 10 was not
observed. The structure of 8a was independently con-
2-Benzyl-4-tolyl-1,3-selenazole (3b)
Yield: 77%; colorless needles (EtOH); mp 100–101 °C.
firmed by the synthesis of 10. The cyclization of
selenourea10 with phenacyl bromide afforded the 2-ami-
IR (KBr): 820 (s), 890 (w), 1040 (s), 1130 (s), 1310 (w), 1320 (w),
1430 (m), 1460 (s), 1510 (s), 2930 (w), 3030 (m), 3120 (m) cm–1.
no-1,3-selenazole 9 which was transformed into 10 by
1H NMR (300 MHz, CDCl3): = 2.36 (s, 3 H, Me), 4.33 (s, 2 H,
treatment with benzoyl chloride.
CH2), 7.19–7.78 (m, 9 H, ArH), 7.89 (s, 2JSeH = 47.20 Hz, 1 H, 5-H,
Hetar).
[NH3(OH)]Cl
EtOH, H2O
Ph
Ph
13C NMR (75 MHz, CDCl3): = 21.35 (Me), 43.29 (CH2, Bn),
118.01 (5-C, Hetar), 126.52 (Ar), 127.32 (Ar), 128.86 (Ar), 129.28
(Ar), 129.38 (Ar), 132.82 (Ar), 137.52 (Ar), 138.39 (Ar), 155.84 (4-
C, Hetar), 172.79 (1J2-C–Se = 106.23 Hz, 2-C, Hetar).
N
R1
N
Se
R1
Se
reflux, 1 h
O
NOH
7a-c
4a,f,j
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 735.6.
PCl5
EtOH
reflux
(R1 = Ph)
MS (70 eV): m/z = 314 (86) [M+], 233 (4), 219 (21), 197 (100), 196
(58), 195 (88), 194 (67), 193 (60), 176 (12), 162 (13), 127 (4), 115
(95), 91 (65), 78 (14),66 (29), 43 (25), 39 (18).
Ph
N
NHR1
Anal. Calcd for C17H15NSe (312.27): C, 65.39; H, 4.84; N, 4.48.
Found: C, 65.40; H, 5.30; N, 4.54.
Se
O
R1
Ph
N
8a (R1 = C6H5): 80%
8b (R1 = 4-ClC6H4): 92%
O
N
2-Benzyl-4-(4-bromophenyl)-1,3-selenazole (3c)
Yield: 100%; colorless needles; mp 100–101 °C.
Se
H
10 (R1 = C6H5): 59%
IR (KBr): 820 (s), 890 (w), 1040 (s), 1130 (s), 1310 (m), 1320 (m),
1425 (m), 1470 (s), 1510 (s), 2220 (w), 3030 (w), 3120 (m) cm–1.
R1COCl
1H NMR (200 MHz, DMSO-d6): = 4.35 (s, 2 H, CH2, Bn), 7.32–
Se
7.91 (m, 9 H, ArH), 8.55 (s, 2JSeH = 47.1 Hz, 1 H, 5-H, Hetar).
EtOH
reflux
Ph
N
H2N
Ph
NH2
Br
13C NMR (50 MHz, DMSO-d6): = 42.03 (CH2, Bn), 120.70 (Ar),
121.41 (5-C, Hetar), 127.09 (CH, Ar), 128.22 (CH, ArH), 128.75
(CH, Ar), 131.66 (CH, Ar), 134.22 (Ar), 138.42 (Ar), 153.10 (4-C,
Hetar), 177.77 (2-C, Hetar).
+
NH2
Se
O
9 (87%)
Scheme 4 Synthesis and reactions of ketoximes 7a–c. 7a (R1
C6H5): 87%, 7b (R1 = 4-ClC6H4): 77%, 7c (R1 = 4-O2NC6H4): 76%
=
MS (70 eV): m/z = 377 (100) [M+], 375 (48), 262 (58), 260 (73), 258
(34), 207 (6), 182 (23), 180 (23), 127 (5), 101 (23), 91 (28), 89 (25),
77 (4), 76 (12), 65 (11), 51 (11), 28 (11).
Anal. Calcd for C16H12NBrSe (377.15): C, 50.95; H, 3.21; N, 3.71.
Found: C, 50.10; H, 3.00; N, 3.79.
In summary, the synthesis of the first 2-acyl-1,3-selena-
zoles was reported. These compounds represent useful
building blocks for the synthesis of 2-unsubstituted 1,3-
selenazoles and 2-carbamoyl-1,3-selenazoles.
2-Benzyl-4-(4-nitrophenyl)-1,3-selenazole (3d)
Yield: 88%; colorless needles; mp 121.5–123 °C.
IR (KBr): 705 (m), 731 (m), 754 (w), 774 (w), 827 (w), 848 (m), 860
(m) 1037 (w), 1109 (s), 1318 (m), 1341 (s), 1422 (w), 1506 (s), 1518
(s), 1596 (s), 3089 (w) cm–1.
Synthesis of 2-Arylmethyl-1,3-selenazoles (3); General Proce-
dure
An EtOH solution (20 mL) of the substituted -bromoacetophenone
1 (1.0 mmol) and the arylselenoacetic amide 2 (1.0 mmol) was re-
fluxed for 5 min. After cooling to 20 °C, the precipitate was filtered
off and recrystallized from EtOH to give 3 as colorless needles.
1H NMR (200 MHz, CDCl3): = 4.34 (CH2, Bn), 7.35–8.23 (m, 9
H, ArH), 8.27 (s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 43.20 (s, 2 H, CH2, Bn), 122.80 (5-
C, Hetar) 124.15 (CH, Ar), 127.06 (CH, Ar), 127.54 (CH, Ar),
128.99 (CH, Ar), 129.21 (CH, Ar) 137.89 (Ar), 141.21 (Ar), 146.91
(Ar), 153.42 (4-C, Hetar), 179.11 (2-C, Hetar).
2-Benzyl-4-phenyl-1,3-selenazole (3a)
MS (70 eV): m/z = 344 (100) [M+], 298 (5), 227 (62), 197 (21), 181
Yield: 0.29 g (99%); mp 99.5–100 °C.
(17), 169 (9), 127 (6), 117 (9), 89 (53), 77 (5), 76 (10), 66 (11), 28
(3).
IR (KBr): 885 (w), 1042 (s), 1125 (s), 1310 (w), 1320 (w), 1330 (w),
1420 (m), 1465 (m), 1520 (s), 3050 (w), 3080 (w) cm–1.
1H NMR (300 MHz, CDCl3): = 4.34 (s, 2 H, CH2), 7.31–7.90 (m,
Anal. Calcd for C16H12NO2Se (343.18): C, 55.99; H, 3.52; N, 8.16.
Found: C, 55.60, H, 3.20; N, 8.19.
10 H, Ar), 7.96 (s, 2JSeH = 51.3 Hz, 1 H, 5-H, Hetar).
13C NMR (75 MHz, CDCl3): = 43.28 (CH2, Bn), 118.86 (1J5-C–Se
106.6 Hz, 5-C, Hetar), 126.62 (Ar), 127.33 (Ar), 127.75 (Ar),
128.70 (Ar), 128.87 (Ar), 129.27 (Ar), 135.51 (Ar), 138.34 (Ar),
155.78 (4-C, Hetar), 177.95 (2-C, Hetar).
=
2-Benzyl-4,5-diphenyl-1,3-selenazole (3e)
Yield: 88%; colorless needles (EtOH–H2O); mp 121.5–123 °C.
IR (KBr): 835 (m), 1040 (s), 1130 (s), 1305 (w), 1320 (w), 1330
(w), 1420 (m), 1465 (m), 1515 (s), 3050 (w), 3080 (w) cm–1.
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 738.79.
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K. Geisler et al.
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2-(4-Chlorobenzyl)-4-(4-nitrophenyl)-1,3-selenazole (3i)
1H NMR (200 MHz, CDCl3): = 4.22 (s, 2 H, CH2, Bn), 7.12–7.43
(m, 15 H, ArH).
Yield: 67%; yellow needles (EtOH); mp 134–135 °C.
13C NMR (50 MHz, CDCl3): = 43.41 (CH2, Bn), 127.37 (CH, Ar)
127.44 (CH, Ar), 127.66 (CH, Ar), 128.19 (CH, Ar), 128.50 (CH,
Ar), 128.89 (CH, Ar), 129.24 (CH, Ar), 129.36 (CH, Ar), 129.64
(CH, Ar), 134.30 (Ar), 135.51 (Ar), 138.38 (Ar), 140.34 (5-C,
Hetar), 149.69 (4-C, Hetar), 176.21 (2-C, Hetar).
MS (70 eV): m/z = 375 (51) [M+], 258 (49), 256 (27), 178 (100), 151
(10), 126 (3), 117 (4), 91 (15), 77 (8), 28 (4).
IR (KBr): 850 (s), 880 (w), 1020 (m), 1040 (m), 1100 (m), 1120
(m), 1340 (s), 1520 (s), 1605 (s), 3080 (w), 3120 (w) cm–1.
1H NMR (200 MHz, CDCl3): = 4.35 (s, 2 H, CH2) 7.26–8.30 (m,
9 H, ArH, Hetar).
13C NMR (50 MHz, CDCl3): = 42.46 (CH2), 122.91 (5-C, Hetar),
124.14 (CH, Ar), 127.05 (CH, Ar), 129.11 (CH, Ar), 130.53 (CH,
Ar), 133.45 (Ar), 136.25 (Ar), 141.05 (Ar), 146.92 (Ar), 153.50 (4-
C, Hetar), 177.94 (2-C, Hetar).
Anal. Calcd for C22H17NSe (374.35): C, 70.59; H, 4.58; N, 3.74.
Found: C, 70.60; H, 4.30; N, 3.66.
MS (70 eV): m/z = 378 (100) [M+], 332 (4), 297 (3), 227 (46), 197
(11), 181 (10), 125 (19), 101 (6), 89 (39), 75 (7), 51 (4).
2-(4-Chlorobenzyl)-4-phenyl-1,3-selenazole (3f)
Yield: 60%; colorless rods (EtOH); mp 108.5–110 °C.
Anal. Calcd for C16H11N2O2ClSe (377.69): C, 50.88; H, 2.94; N,
7.42. Found: C, 50.72; H, 2.98; N, 7.19.
IR (KBr): 840 (s), 885 (w), 920 (m), 940 (m), 1100 (s), 1130 (s),
1410 (w), 1420 (w), 1515 (s) cm–1.
2-(4-Nitrobenzyl)-4-phenyl-1,3-selenazole (3j)
Yield: 78%; colorless needles (EtOH); mp 120.5 °C.
1H NMR (300 MHz, CDCl3): = 4.30 (s, 2 H, CH2), 7.31–7.89 (m,
9 H, ArH), 7.92 (s, 2JSeH = 49.20 Hz, 1 H, 5-H, Hetar).
IR (KBr): 860 (m), 885 (w), 1040 (m), 1090 (m), 1120 (m), 1190
(w), 1355 (s), 1430 (w), 1440 (m), 1480 (m), 1530 (s), 1605 (s),
3110 (m) cm–1.
13C NMR (75 MHz, CDCl3): = 42.53 (CH2, Bn), 118.98 (1J5-C–Se
105.99 Hz, 5-C, Hetar), 126.60 (Ar), 127.83 (Ar), 128.71 (Ar),
128.99 (Ar), 130.57 (Ar), 133.23 (Ar), 135.34 (Ar), 136.68 (Ar),
155.86 (4-C, Hetar), 176.79 (1J2-C–Se = 134.30 Hz, 2-C).
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 739.6.
MS (70 eV): m/z = 333 (70) [M+] (70), 330 (13), 182 (100), 180
=
1H NMR (300 MHz, CDCl3): = 4.47 (s, 2 H, CH2), 7.30–8.24 (m,
9 H, ArH), 8.03 (s, 2JSeH = 47.7 Hz, 1 H, 5-H, Hetar).
13C NMR (75 MHz, CDCl3): = 42.80 (CH2), 119.29 (5-C, Hetar),
124.03 (Ar), 126.61 (Ar), 128.00 (Ar), 128.76 (Ar), 130.02 (Ar),
135.09 (Ar), 145.30 (Ar), 147.20 (Ar), 156.06 (4-C, Hetar), 174.02
(2-C, Hetar).
(50), 125 (20), 115 (13), 102 (88), 89 (20), 77 (10), 51 (7), 28 (2).
Anal. Calcd for C16H12NSeCl (332.69): C, 57.76; H, 3.64; N 4.21.
Found: C, 57.81; H, 4.01: N, 3.98.
77Se (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 742.80.
MS (70 eV): m/z = 344 (56) [M+], 182 (87), 102 (100), 89 (16), 77
(9), 51 (5), 28 (22).
2-(4-Chlorobenzyl)-4-tolyl-1,3-selenazole (3g)
Yield: 71%; colorless needles (EtOH); mp 140.5–141.5 °C.
Anal. Calcd for C16H12N2O2Se (343.23): C, 55.97; H, 3.50; N, 8.16.
Found: C, 56.00, H, 3.80; N, 8.28.
IR (KBr): 830 (m), 885 (w), 1020 (m), 1040 (m), 1100 (m), 1125
(s), 1410 (w), 1420 (m), 1515 (s), 2930 (w), 3035 (w), 3120 (w)
cm–1.
2-(4-Nitrobenzyl)-4-(4-tolyl)-1,3-selenazole (3l)
Yield: 86%; colorless needles (EtOH); mp 94.5 °C.
1H NMR (200 MHz, CDCl3): = 2.38 (s, 3 H, Me), 4.31 (s, 3 H,
CH2), 7.20–7.80 (m, 9 H, ArH), 7.93 (s, 2JSeH = 47.1 Hz, 1 H, 5-H,
Hetar).
IR (KBr): 830 (m), 860 (m), 890 (w), 1030 (m), 1080 (m), 1120 (s),
1330 (m), 1355 (s), 1515 (s), 1605 (m), 3030 (w), 3080 (w), 3130
(w) cm–1.
1H NMR (300 MHz, CDCl3): = 2.36 (s, 3 H, Me), 4.46 (s,
3JSe–CH2 = 40.2 Hz, 2 H, CH2), 7.17–8.20 (m, 8 H, ArH), 7.94 (s,
2JSeH = 47.80 Hz, 1 H, 5-H, Hetar).
13C NMR (75 MHz, CDCl3): = 21.24 (Me), 42.76 (CH2), 118.46
(1J5-C–Se = 135 Hz, 5-C, Hetar), 123.97 (Ar), 126.52 (Ar), 128.78
(Ar), 129.44 (Ar), 130.02 (Ar), 132.82 (Ar), 145.36 (Ar), 147.14
(Ar), 156.08 (4-C, Hetar), 174.05 (2-C, Hetar).
13C NMR (50 MHz, CDCl3): = 21.24 (Me), 42.42 (CH2, Bn),
118.11 (5-C, Hetar), 126.47 (CH, Ar), 128.96 (CH, Ar), 129.38
(CH, Ar), 130.57 (CH, Ar) 132.61 (Ar), 133.19 (Ar), 136.71 (Ar),
137.63 (Ar), 155.89, (4-C, Hetar), 176.68 (2-C, Hetar).
MS (70 eV): m/z = 347 (77) [M+], 251 (5), 198 (19), 196 (100), 194
(54), 125 (27), 116 (49), 115 (76), 89 (21), 77 (3), 64 (9), 28 (2).
Anal. Calcd for C17H12NClSe (344.69): C, 59.24; H, 3.51; N, 4.06.
Found: C, 58.94; N, 4.22; N, 4.19.
77Se (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 739.7.
2-(4-Chlorobenzyl)-4-(4-bromophenyl)-1,3-selenazole (3h)
Yield: 73%; colorless needles (EtOH); mp 128–129 °C.
MS (70 eV): m/z = 358 (77), 196 (100), 194 (55), 110 (59), 114 (93),
89 (17), 77 (3), 28 (41), 28 (41).
IR (KBr): 840 (s), 850(s), 890 (w), 1010 (s), 1100 (s), 1125 (s), 1315
(w), 1405 (w), 1515 (s), 1630 (m), 3120 (w) cm–1.
Anal. Calcd for C17H14N2O2Se (357.27): C, 57.15; H, 3.95, N, 7.84.
Found: C, 57.20; H, 3.98, N, 7.64.
1H NMR (200 MHz, CDCl3): = 4.30 (s, 2 H, CH2), 7.32–7.29 (m,
8 H, ArH), 8.00 (s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar).
4-(4-Nitrobenzyl)-4-(4-bromophenyl)-1,3-selenazole (3m)
Yield: 86%; colorless needles (EtOH); mp 167–169 °C.
13C NMR (50 MHz, CDCl3): = 42.00 (CH2), 119.44 (5-C), 121.76
(Ar) 128.13 (CH, Ar) 129.04 (CH, Ar), 130.55 (CH, Ar), 131.79
(CH, Ar), 133.31 (Ar), 134.21 (Ar), 136.52 (Ar), 154.66 (4-C,
Hetar), 177.24 (2-C, Hetar).
MS (70 eV): m/z = 411 (100) [M+], 372 (2), 260 (99), 180 (36), 148
(2), 125 (12), 101 (30), 89 (29), 75 (13), 63 (6), 51 (7).
IR (KBr): 835 (m), 860 (m), 885 (w), 1010 (m), 1035 (m), 1070 (m),
1120 (m), 1135 (m), 1190 (w), 1320 (m), 1350 (s), 1400 (w), 1430
(w), 1515 (s), 1605 (m), 3105 (w) cm–1.
1H NMR (300 MHz, CDCl3): = 4.46 (s, 2 H, CH2), 7.51–8.25 (m,
8 H, ArH), 8.04 (s, 2JSeH = 47.20 Hz, 1 H, 5-H, Hetar).
Anal. Calcd for C16H11NClSe (411.59): C, 46.69; H, 2.69: N, 3.40.
Found: C, 46.71; H, 2.79; N, 3.27.
13C NMR (75 MHz, CDCl3): = 42.78 (CH2), 119.75 (5-C, Hetar),
121.96 (Ar), 124.08 (Ar), 128.17 (Ar), 130.03 (Ar), 131.86 (Ar),
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Synthesis and Reactivity of 2-Acyl-1,3-selenazoles
101
134.00 (Ar), 145.14 (Ar), 147.26 (Ar), 154.90 (4-C, Hetar), 174.44
(2-C, Hetar).
77Se (38.18 MHz, CDCl3, Me2Se): = 752.4.
MS (70 eV): m/z = 423 (90) [M+], 262 (77), 260 (100), 181 (41), 180
(52), 127 (5), 101 (41), 89 (52), 76 (19), 64 (16), 30 (15), 28 (7).
13C NMR (75 MHz, CDCl3): = 21.28 (Me) 126.00 (CH), 126.56
(CH), 128.35 (CH), 129.55 (Ar), 131.41 (CH), 133.54 (Ar), 134.51
(Ar), 138.31 (Ar), 158.80 (4-C, Hetar), 174.84 (2-C, Hetar), 184.61
(C=O).
MS (70 eV): m/z = 327 (25) [M+], 299 (3), 196 (7), 114 (14), 105
(100), 77 (55), 51 (11), 28 (2).
Anal. Calcd for C16H11N2O2SeBr (422.12): C, 45.50; H, 2.60, N,
6.63. Found: C, 45.80; H, 2.60; N 6.56.
Anal. Calcd for C17H13NOSe (326.25): C, 62.59; H, 4.01; N, 4.29.
Found: C, 62.75; H, 3.66; N, 4.56.
2-(4-Nitrobenzyl)-4-(4-nitrobenzyl)-1,3-selenazole (3n)
Yield: 81%; orange needles (EtOH); mp 162–164 °C.
2-Benzoyl-4-(4-bromophenyl)-1,3-selenazole (4c)
Yield (Method A): 60%, (Method B): 80%; yellow needles (EtOH);
mp 143.5–145 °C.
IR (KBr): 840 (m), 860 (s), 1110 (s), 1130 (m), 1340 (s), 1410 (m),
1515 (s), 1600 (m), 3090 (w), 3115 (w) cm–1.
IR (KBr): 845 (m), 905 (s), 1015 (m), 1085 (m), 1110 (m), 1190
(w), 1270 (s), 1298 (s), 1470 (s), 1501 (s), 1605 (m), 1630 (s) cm–1.
1H NMR (300 MHz, DMSO-d6): = 4.62 (s, 2 H, CH2), 7.70–8.30
(m, 8 H, ArH), 8.93 (s, 2JSeH = 45.20 Hz, 1 H, 5-H, Hetar).
1H NMR (200 MHz, CDCl3): = 7.52–8.60 (m, 9 H, ArH), 8.52 (s,
13C NMR (75 MHz, DMSO-d6): = 46.5 (CH2), 119.85 (5-C,
Hetar), 128.97 (Ar), 129.37 (Ar), 131.07 (Ar), 132.27 (Ar), 135.57
(Ar), 145.95 (Ar), 151.12 (Ar), 151.52 (Ar), 157.43 (4-C, Hetar),
180.98 (2-C, Hetar).
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
772.7.
2JSeH = 42 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 122.45 (Ar), 127.10 (5-C, Hetar),
128.18 (CH, Ar) 128.42 (CH, Ar) 131.34 (CH, Ar), 132.02 (CH,
Ar), 133.70 (CH, Ar) 133.7 (Ar), 134.35 (Ar), 157.48 (4-C, Hetar),
175.34 (2-C, Hetar), 184.51 (C=O).
=
MS (70 eV): m/z = 391 (26), 363 (3), 260 (3), 207 (2), 180 (3), 127
(3), 118 (8), 105 (100), 77 (35), 51 (4).
MS (70 eV): m/z = 389 (100) [M+], 386 (46), 344 (13), 227 (44), 197
(18), 182 (34), 117 (14), 102 (40), 89 (67), 77 (8), 64 (10), 28 (58).
Anal. Calcd for C16H10NBrOSe (391.11): C, 49.14; H, 2.58; N,
3.58. Found: C, 49.20; H, 2.37; N, 3.41.
Anal. Calcd for C16H11N3O4Se (388.2): C, 49.50; H, 2.26; N, 10.82.
Found: C, 49.30; H, 2.31; N 10.83.
2-Benzoyl-4-(4-nitrophenyl)-1,3-selenazole (4d)
Yield (Method A): 76%, (Method B): 70%; yellow needles (EtOH);
mp 192–193.5 °C.
Synthesis of 2-Acyl-1,3-selenazoles (4); General Procedure
Method A: To a solution of 3 (5.0 mmol) in HOAC (50 mL) was
added potassium dichromate (2.94 g, 10.0 mmol) with stirring. The
mixture was refluxed for 1 h. After cooling to 20 °C, the solution
was poured into ice water (100 mL) to give a crystalline precipitate.
The latter was filtered off, washed (water), dried in vacuo and re-
crystallized (EtOH) to give 4 as yellow needles.
IR (KBr): 860 (m), 1030 (m), 1120 (s), 1190 (w), 1345 (s), 1425
(w), 1475 (s), 1530 (s), 1605 (s), 3115 (s) cm–1.
1H NMR (200 MHz, CDCl3): = 7.49–8.60 (m, 9 H, ArH), 8.12 (s,
2JSeH = 44 Hz, 1 H, 5-H).
Method B: To a dioxane solution (20 mL) of 3 (5.0 mmol) was add-
ed SeO2 (0.55 g, 5.0 mmol) with stirring. The mixture was heated
(water bath) at 40 °C for 3 h. The hot solution was filtered, cooled,
and poured into ice water (50 mL). The work up was carried out as
described for Method A.
13C NMR (75 MHz, CDCl3): = 124.34 (CH), 127.23 (CH), 128.59
(CH), 130.08 (CH), 131.30 (CH), 133.94 (CH), 134.53 (Ar), 134.13
(Ar), 140.55 (Ar), 147.39 (Ar), 156.14 (4-C, Hetar), 174.81 (2-C,
Hetar), 184.39 (C=O).
Anal. Calcd for C16H10N2O3Se (357.2): C, 53.80; H, 2.82; N, 7.84.
Found: C, 53.46; H, 2.92; N, 7.56.
2-Benzoyl-4-phenyl-1,3-selenazole (4a)
Yield: 1.00 g (64%); mp 76–77 °C.
2-Benzoyl-4,5-diphenyl-selenazole (4e)
IR (KBr): 840 (m), 901 (m), 1025 (w), 1050 (w), 1075 (w), 1110
(w), 1190 (m), 1270 (s), 1298 (s), 1430 (s), 1465 (s), 1505 (s) cm–1.
Yield (Method A): 70%; beige needles (EtOH); mp 135.5–136.5 °C.
IR (KBr): 8.20 (m), 885 (s), 930 (w), 960 (w), 1010 (w), 1030 (w),
1080 (w), 1120 (m), 1190 (s), 1225 (m), 1295 (s), 1430 (s), 1460 (s),
1495 (m), 1503 (s), 1590 (m), 1605 (s), 1630 (s), 3090 (w) cm–1.
1H NMR (300 MHz, CDCl3): = 7.38–8.62 (m, 10 H, ArH), 8.54
(s, 2JSeH = 50 Hz, 1 H, 5-H).
13C NMR (75 MHz, CDCl3): = 119.87 (5-C, Hetar), 126.71 (Ar),
126.77 (Ar), 128.43 (Ar), 128.93 (Ar), 131.45 (Ar), 133.63 (Ar),
134.53 (Ar), 134.92 (Ar), 158.70 (4-C, Hetar), 175.08 (2-C), 184.67
(C=O).
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 807.31.
MS (70 eV): m/z = 312 (24) [M+], 299 (3), 285 (2), 182 (10), 105
1H NMR (300 MHz, CDCl3): = 7.30–8.62 (m, 15 H, ArH).
13C NMR (75 MHz, CDCl3): = 127.93 (CH, Ar), 128.28 (CH, Ar),
128.36 (CH, Ar), 128.69 (CH, Ar), 128.80 (CH, Ar), 129.41 (CH,
Ar), 129.59 (CH, Ar), 131.37 (CH, Ar), 133.48 (CH, Ar), 133.65
(Ar), 134.50 (Ar), 149.39 (Ar), 153.01 (4-C, Hetar), 172.53 (2-C,
Hetar), 184.74 (C=O).
(100), 102 (17), 77 (63), 51 (16), 28 (14).
MS (70 eV): m/z = 389 (34) [M+], 361 (6), 258 (14), 204 (3), 178
(31), 151 (3), 105 (100), 77 (66), 51 (13), 28 (13).
Anal. Calcd for C16H11NOSe (312.22): C, 61.55; H, 3.55; N, 4.49.
Found: C, 61.80; H, 3.90; N, 4.29.
Anal. Calcd for C22H15NOSe (388.32): C, 68.05; H, 3.89; N, 3.61.
Found: C, 68.28; H, 3.78; N, 3.50.
2-Benzoyl-4-tolyl-1,3-selenazole (4b)
Yield (Method B): 74%; golden prisms (EtOH); mp 94.5–95.5 °C.
2-(4-Chlorobenzoyl)-4-phenyl-selenazole (4f)
Yield (Method A): 45%, (Method B): 84%; yellow needles (EtOH);
mp 135–136 °C.
IR (KBr): 830 (s), 900 (s), 1060 (m), 1120 (m), 1190 (m), 1270 (s),
1298 (s), 1470 (s), 1510 (s), 1660 (s), 2930 (w) cm–1.
IR (KBr): 840 (s), 902 (s), 1020 (m), 1030 (m), 1070 (m), 1099 (s),
1120 (m), 1190 (s), 1270 (s), 1298 (s), 1430 (s), 1468 (m), 1495 (s),
1590 (w), 1598 (s), 1580 (m), 1598 (s), 1630 (s), 3025 (w) cm–1.
1H NMR (200 MHz, CDCl3): 2.41 (s, 3 H, Me), 7.21–8.62 (m, 9 H,
ArH), 8.47 (s, 2JSeH = 44 Hz, 1 H, 5-H).
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1H NMR (200 MHz, CDCl3): = 7.33–8.59 (m, 9 H, ArH), 8.54 (s,
Anal. Calcd for C16H9N2O3ClSe (391.64): C, 49.07; H, 2.32; N,
7.15. Found: C, 49.00; H, 2.35; N, 6.88.
2JSeH = 47 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 126.63 (CH, Ar), 127.12 (5-C,
Hetar), 128.52 (CH, Ar), 128.75 (CH, Ar), 128.95 (CH, Ar), 132.80
(CH, Ar), 134.71 (Ar), 140.28 (Ar), 158.78 (4-C, Hetar), 174.65 (2-
C, Hetar), 183.32 (C=O).
2-(4-Nitrobenzoyl)-4-phenyl-1,3-selenazole (4j)
Yield (Method A): 53%, (Method B): 72%; yellow needles (EtOH);
mp 151–153 °C.
IR (KBr): 830 (s), 870 (m), 902 (w), 1045 (m), 1095 (m), 1110 (m),
1190 (w), 1270 (m), 1297 (m), 1345 (s), 1430 (w), 1520 (s), 1608
(s), 3120 (w) cm–1.
MS (70 eV): m/z = 347 (19) [M+], 319 (4), 207 (3), 182 (8), 141
(28), 139 (100), 111 (50), 102 (16), 89 (5), 77 (4), 76 (8), 75 (18),
51 (4).
1H NMR (300 MHz, CDCl3): = 7.41–8.76 (m, 9 H, ArH), 8.64 (s,
Anal. Calcd for C16H10NOClSe (346.69): C, 55.43; H, 2.91; N, 4.04.
Found: C, 55.69; H, 2.69; N, 4.24.
2JSeH = 45.3 Hz, 1 H, 5-H, Hetar).
13 C NMR (75 MHz, CDCl3): = 123.43 (5-C, Hetar), 126.69 (Ar),
128.91 (Ar), 129.07 (Ar), 132.35 (Ar), 134.47 (Ar), 139.50 (Ar),
150.49 (Ar), 159.26 (4-C, Hetar), 173.63 (2-C, Hetar), 183.24
(C=O).
2-(4-Chlorobenzoyl)-4-(4-tolyl)-1,3-selenazole (4g)
Yield (Method A): 79%; (Method B): 84%; yellow needles (EtOH);
mp 132.5–135 °C.
IR (KBr): 830 (m), 840 (s), 902 (s), 1015 (s), 1080 (m), 1095 (s),
1112 (m), 1190 (s), 1160 (s), 1195 (s), 1440 (s), 1495 (s), 1580 (s),
1598 (s), 1630 (s), 3110 (m) cm–1.
77Se NMR (38.18 MHz, CDCl3, MeSe): = 816.78.
MS (70 eV): m/z = 358 (40) [M+], 330 (6), 182 (24), 149 (100), 120
(21), 104 (51), 92 (26), 77 (44), 50 (14), 28 (8).
1H NMR (200 MHz, CDCl3): = 2.40 (s, 3 H, Me), 7.24–8.60 (m,
Anal. Calcd for C16H10N2O3Se (357.23): C, 53.79; H, 2.82; N, 7.84.
Found: C, 54.79; H, 3.61; N, 7.64.
8 H, ArH), 8.48 (s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 21.29 (Me), 126.35 (5-C, Hetar),
126.53 (CH, Ar), 128.72 (CH, Ar), 129.60 (CH, Ar), 132.03, 132.80
(CH, Ar) 138.45 (Ar), 140.21 (Ar), 158.88 (4-C, Hetar), 174.47 (2-
C, Hetar), 183.30 (C=O).
2-(4-Nitrobenzoyl-4-tolyl-1,3-selenazole (4k)
Yield (Method A): 42%, (Method B): 83%; golden lamella; mp 187–
189 °C.
MS (70 eV): m/z = 361 (31), 251 (2), 196 (10), 139 (100), 110 (38),
28 (19).
IR (KBr): 830 (s), 871 (m), 901 (s), 1011 (w), 1071 (w), 1109 (s),
1190 (m), 1272 (s), 1295 (s), 1325 (s), 1351 (s), 1439 (s), 1501 (s),
1525 (s), 1605 (s), 1661 (s), 3120 (w) cm–1.
Anal. Calcd for C17H12NClOSe (360.69): C, 56.61; H, 3.35; N, 3.88.
Found: C, 56.54; H, 3.86; N, 3.89.
1H NMR (300 MHz, DMSO-d6): = 2.36 (s, 3 H, Me), 7.30–8.66
(m, 8 H, ArH), 9.20 (s, 2JSeH = 45.1 Hz, 1 H, 5-H, Hetar).
2-(4-Chlorobenzoyl)-4-(4-bromophenyl)-1,3-selenazole (4h)
Yield (Method A): 50%; yellow needles (EtOH); mp 171.5–173 °C.
13C NMR (75 MHz, DMSO-d6): = 21.15 (Me), 123.89 (5-C,
Hetar), 126.79 (Ar), 129.96 (Ar), 130.10 (Ar), 131.80 (Ar), 137.47
(Ar), 138.49 (Ar), 139.71 (Ar), 150.39 (Ar), 158.29 (4-C, Hetar),
173.56 (5-C, Hetar), 184.08 (C=O).
IR (KBr): 840 (s), 901 (s), 970 (w), 1010 (m), 1060 (m), 1090 (s),
1098 (s), 1190 (s), 1270 (s), 1295 (s), 1298 (s), 1401 (m), 1435 (s),
1493 (s), 1592 (m), 1596 (s), 1640 (s), 3110 (w) cm–1.
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
=
1H NMR (200 MHz, DMSO-d6): = 7.63–8.46 (m, 8 H, ArH), 9.26
815.3.
(s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar).
MS (70 eV): m/z = 371 (57) [M+], 344 (4), 196 (34), 194 (16), 149
(100), 120 (26), 104 (57), 92 (28), 77 (43), 50 (10), 28 (15).
13C NMR (50 MHz, DMSO-d6,): = 121.26 (5-C, Hetar), 128.14
(CH, Ar), 128.14 (CH, Ar), 129.87 (Ar), 131.48 (CH, Ar) 132.18
(CH, Ar), 132.55 (Ar), 133.32 (Ar), 138.66 (Ar), 156.07 (4-C,
Hetar), 173.92 (2-C, Hetar), 180.27 (C=O).
Anal. Calcd for C17H12N2O3Se (371.23): C, 55.00; H, 3.26; N, 7.54.
Found: C, 54.79; H, 3.61; N, 7.64.
MS (70 eV): m/z = 425 (29) [M+], 260 (2), 207 (4), 180 (3), 139
(100), 111 (44), 75 (12), 50 (3).
2-(4-Nitrobenzoyl)-4-(4-bromophenyl)-1,3-selenazole (4l)
Yield (Method A): 57%, (Method B): 60%; yellow needles (HOAc);
mp 211–213 °C.
Anal. Calcd for C16H9NOClBrSe (425.57): C, 45.16; H, 2.13; N,
3.29. Found: C, 45.22; H, 2.21; N, 3.01.
IR (KBr): 830 (s), 870 (m), 905 (s), 1010 (m), 1061 (m), 1081 (m),
1112 (s), 1191 (m), 1271 (s), 1298 (s), 1331 (m), 1345 (s), 1431 (s),
1501 (s), 1528 (s), 1608 (s), 1661 (s), 3120 (w) cm–1.
2-(4-Chlorobenzoyl)-4-(4-nitrophenyl)-1,3-selenazole (4i)
Yield (Method A): 62%, (Method B): 72%; yellow needles (C6H6);
mp 241 °C.
1H NMR (300 MHz, DMSO-d6): = 7.37–8.64 (m, 8 H, ArH), 9.36
(s, 2JSeH = 44.5 Hz, 1 H, 5-H, Hetar).
IR (KBr): 830 (s), 865 (s), 904 (s), 970 (w), 1015 (m), 1075 (w),
1101 (s), 1190 (m), 1280 (s), 1299 (s), 1330 (m), 1345 (s), 1405 (m),
1441 (m), 1490, 1520 (s), 1605 (s), 1645 (s), 3110 (w) cm–1.
MS (70e V): m/z = 436 (50) [M+], 260 (8), 207 (4), 180 (8), 150
(100), 120 (10), 104 (36), 76 (26), 50 (8).
Anal. Calcd for C16H9N2O3BrSe (436.09): C, 44.07; H, 2.08; N,
6.42. Found: C, 44.09; H, 2.15; N, 6.61.
1H NMR (200 MHz, DMSO-d6) = 7.62–8.25 (m, 8 H, ArH), 9.52
(s, 2JSeH = 46 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, DMSO-d6): = 124.06 (5-C, Hetar), 127.34
(CH, Ar), 128.67 (CH, Ar), 132.48 (CH, Ar), 133.54 (CH, Ar),
138.92 (Ar), 140.04 (Ar), 146.85 (Ar), 154.98 (5-C, Hetar), 174.64
(2-C, Hetar), 183.15 (C=O).
MS (70 eV): m/z = 392 (12) [M+], 364 (7), 207 (2), 141 (30), 139
(100), 111 (30), 77 (2), 76 (4), 75 (11), 50 (3).
2-(4-Nitrobenzoyl)-4-(4-nitrophenyl)-1,3-selenazole (4m)
Yield (Method A): 82%, (Method B): 58%; yellow lamella (EtOAc);
mp 258–260 °C.
IR (KBr): 830 (s), 861 (m), 905 (m), 1020 (w), 1071 (m), 1110 (s),
1270 (s), 1298 (s), 1320 (s), 1345 (s), 1435 (m), 1515 (s), 1625 (s),
1655 (m), 3120 (w) cm–1.
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1H NMR (300 MHz, DMSO-d6): = 7.15–8.66 (m, 8 H, ArH), 9.57
(s, 2JSeH = 43.80 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 118.9 (5-C, Hetar), 121.97 (Ar),
128.21 (CH, Ar), 131.87 (CH, Ar), 133.96 (Ar), 155.78 (4-C,
Hetar), 158.68 (2-C, Hetar).
MS (70 eV): m/z = 287 (100) [M+], 289 (80) [M+], 260 (59), 262
(50), 180 (39), 130 (3), 117 (3), 104 (16), 101 (42), 99 (24), 75 (26),
63 (6), 51 (12).
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
=
1241.0.
MS (70 eV): m/z = 402 (26) [M+], 41 (14), 375 (7), 149 (100), 120
(15), 104 (36), 92 (18), 77 (22), 50 (6), 28 (13).
Anal. Calcd for C9H6NBrSe (287.02): C, 37.66; H, 2.10; N, 4.86.
Found: C, 37.32; H, 1.67; N, 4.84.
Anal. Calcd for C16H9N3O3Se (402.18): C, 47.78; H, 2.25; N, 10.45.
Found: C, 10.45; H, 2.27; N, 10.12.
4-(4-Nitrophenyl)-1,3-selenazole (5d)
Yield: 71%; beige needles (EtOH–H2O); mp 158–161 °C.
Synthesis of 2-Unsubstituted 1,3-Selenazoles (5); General Pro-
cedure
An EtOH solution (30 mL) of 4 (3.2 mmol) and NaOH (0.24 g, 6.4
mmol) was refluxed for 1 h. After cooling to 20 °C, the sodium ben-
zoate formed was filtered off and the solution was poured into ice
water to give a precipitate. The latter was filtered off, dried (P4O10)
and recrystallized from petroleum ether (bp 40–70 °C) to give 5 as
colorless needles.
IR (KBr): 820 (s), 870 (s), 897 (m), 1030 (w), 1110 (m), 1180 (m),
1295 (m), 1348 (s), 1445 (m), 1520 (s), 1608 (s), 3110 (w) cm–1.
1H NMR (200 MHz, DMSO-d6): = 8.25–8.26 (m, 4 H, ArH), 9.05
(s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar), 10.21 (s, 2JSeH = 47.1 Hz, 1 H, 2-
H, Hetar).
13C NMR (50 MHz, DMSO-d6): = 123.67 (5-C, Hetar), 125.34
(CH, Ar), 127.15 (CH, Ar), 140.89 (Ar), 146.39 Ar), 153.39 (4-C,
Hetar), 153.39 (2-C, Hetar).
MS (70 eV): m/z = 254 (100) [M+], 227 (24), 224 (16), 208 (8), 197
(16), 181 (24), 169 (12), 128 (4), 117 (4), 101 (11), 89 (62), 75 (18),
63 (12), 51 (10).
4-Phenyl-1,3-selenazole (5a)
The reaction of 4f and 4j with NaOH afforded 5a in 60% and 84%
yields, respectively. Yield: 0.55 g (84%); mp 66–67 °C.
IR (KBr): 815 (s), 890 (s), 931 (m), 1021 (m), 1030 (m), 1080 (w),
1181 (s), 1235 (w), 1291 (m), 1305 (m), 1445 (m), 1495 (s), 3111
(m) cm–1.
Anal. Calcd for C9H6N2O2Se (253.12): C, 42.71; H, 2.39; N, 11.07.
Found: C, 42.64; H, 2.12; N, 11.21.
1H NMR (200 MHz, CDCl3): = 7.34–7.79 (m, 5 H, ArH), 8.19 (s,
2
2JSeH = 47.1 Hz, 1 H, 5-H, Hetar), 9.93 (s, JSeH = 47.1 Hz, 1 H, 2-
4,5-Diphenyl-1,3-selenazole (5e)
Yield: 77%; beige needles (petroleum ether); mp 73–74 °C.
H, Hetar).
13C NMR (50 MHz, CDCl3,): = 118.44 (5-C, Hetar), 126.71 (CH,
Ar), 127.99 (CH, Ar), 128.24 (CH, Ar), 135.03 (Ar), 156.90 (4-C,
Hetar), 158.38 (2-C, Hetar).
MS (70 eV): m/z = 209 (77) [M+] 77), 207 (39) 182 (73), 141 (3),
129 (3), 117 (4), 102 (100), 77 (22), 64 (15), 51 (19), 28 (4).
IR (KBr): 875 (m), 945 (w), 1030 (w), 1080 (w), 1170 (w), 1190
(w), 1270 (w), 1330 (w), 1445 (s), 1495 (m), 1502 (m), 1605 (m),
3080 (m) cm–1.
1H NMR (200 MHz, CDCl3): = 7.30–7.56 (m, 10 H, ArH), 9.86
(s, 2JSeH = 57.26 Hz, 1 H, 2-H, Hetar).
Anal. Calcd for C9H7NSe (208.10): C, 51.90; H, 3.39: N, 6.73.
Found: C, 51.75; H, 3.73; N, 6.75.
13C NMR (50 MHz, CDCl3): = 127.59 (Ar), 128.0 (Ar), 128.34
(Ar), 128.66 (Ar), 129.35 (Ar), 129.84 (Ar), 133.96 (Ar), 135.25
(Ar), 149.18 (5-C, Hetar), 150.85 (4-C, Hetar), 156.78 (2-C, Hetar).
4-Tolyl-1,3-selenazole (5b)
Yield: 90%; colorless needles (petroleum ether); mp 66–68.5 °C.
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 806.24.
MS (70 eV): m/z = 285 (60) [M+], 257 (13), 204 (15), 178 (100), 170
(21), 105 (55), 77 (42).
IR (KBr): 810 (s), 891 (s), 1010 (w), 1024 (w), 1110 (w), 1171 (m),
1125 (m), 1230 (w), 1280 (w), 1300 (m), 1315 (m), 1445 (s), 1495
(s), 2930 (w), 3030 (w), 3070 (w), 3109 (m) cm–1.
Anal. Calcd for C15H11NSe (284.22): C, 63.39; H, 3.90; N, 4.93.
Found: C, 63.21; H, 3.94; N, 4.93.
1H NMR (200 MHz, CDCl3): = 2.35 (s, 3 H, Me), 7.20–7.87 (m,
4 H, ArH), 8.12 (s, 2JSeH = 44 Hz, 1 H, 5-H, Hetar), 9.90 (s, 2JSeH
=
48 Hz, 1 H, 2-H, Hetar).
Synthesis of 1,1-Dicyano-2-phenyl-2-(4-phenyl-selenazol-2-
yl)ethene (6a); Typical Procedure
13C NMR (50 MHz, CDCl3): = 21.22 (Me), 115.57 (5-C, Hetar),
126.58 (CH, Ar), 129.44 (CH, Ar), 132.32 (Ar), 137.81 (Ar), 156.92
(4-C, Hetar), 158.23 (2-C, Hetar).
MS (70 eV): m/z = 223 (84) [M+], 196 (57), 194 (31), 193 (21), 116
(48), 114 (100), 91 (16), 89 (18), 77 (6), 64 (16), 28 (11).
A pyridine solution (15 mL) of 4a (1.65 g, 5.0 mmol) and dicya-
nomethane (0.33 g, 5.0 mmol) was refluxed for 2.5 h. After cooling
to 20 °C, the solution was poured into ice water to give a precipitate.
The latter was filtered off, dried (P4O10) and recrystallized from
EtOH to give 6a as yellow needles (1.20 g, 67%); mp 199.5–200.5
°C.
Anal. Calcd for C10H9NSe (222.15): C, 54.05; H, 4.08; N, 6.30.
Found: C, 54.27; H, 3.77; N, 6.13.
IR (KBr): 810 (w), 1070 (w), 1280 (w), 1330 (m), 1430 (m), 2230
(m), 23.90 (m) cm–1.
4-(4-Bromophenyl)-1,3-selenazole (5c)
Yield: 83%; beige needles (petroleum ether); mp 75–76.5 °C.
1H NMR (300 MHz, CDCl3): = 7.40–8.07 (m, 10 H, ArH), 8.73
(s, 2JSeH = 46.9 Hz, 1 H, 5-H, Hetar).
IR (KBr): 807 (s), 850 (m), 890 (m), 1011 (s), 1120 (m), 1080 (s),
1178 (s), 1295 (m), 1310 (w), 1401 (w), 1490 (s), 3090 (w), 3120
(w) cm–1.
1H NMR (200 MHz, CDCl3): = 7.53–7.85 (m, 4 H, ArH), 8.40 (s,
2JSeH = 47 Hz, 1 H, 5-H, Hetar), 9.92 (s, 2J (SeH) = 47.2 Hz, 1 H, 2-
H, Hetar).
13C NMR (75 MHz, CDCl3): = 80.86, 113.68, 113.75, 127.03
(Ar), 129.09 (Ar), 129.18 (Ar), 129.37 (Ar), 130.25 (Ar), 132.3.
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 828.6.
MS (70 eV): m/z = 361 (59) [M+], 360 (50), 323 (43), 213 (29), 211
(45), 187 (21), 185 (35), 182 (37), 180 (19), 144 (17), 102 (100), 77
(11), 51 (7), 28 (47).
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104
K. Geisler et al.
PAPER
Anal. Calcd for C19H11N3Se (360.28): C, 63.34; H, 3.08; N, 11.66.
Found: C, 63.70; H, 3.10; N, 11.87.
77Se NMR (DMSO-d6, Me2Se): = 844.
MS (70 eV): m/z = 362 (80) [M+], 332 (56), 297 (21), 203 (16), 182
(25), 139 (13), 102 (100), 77 (11), 51 (12), 28 (10).
Synthesis of Phenyl-(4-phenyl-selenazol(-2-yl)-ketone-thiosemi-
carbazone (6b); Typical Procedure
Anal. Calcd for C16H11N2OClSe (361.68): C, 53.14; H, 3.07; N,
7.74. Found: C, 53.18; H, 3.11; N, 7.77.
Selenazole 4a (0.62 g, 2.0 mmol) was dissolved in EtOH (20 mL).
Thiosemicarbazide (0.27 g, 3.0 mmol) was dissolved in a mixture
of H2SO4 (2 mL, 96%) and H2O (3 mL). The solutions were com-
bined and refluxed for 2.5 h. After cooling to 20 °C, a solid precip-
itated. The latter was filtered off and recrystallized from benzene to
give 6b as yellow needles (0.50 g, 68%); mp 201–202 °C.
4-Nitrophenyl-(4-phenyl-selenazol-2-yl)-ketoxime (7c)
Yield: 76%; yellow prisms (EtOH–H2O); mp 205–207 °C.
IR (KBr): 861 (s), 910 (s), 1096 (s), 1136 (m), 1356 (s), 1435 (s),
1491 (s), 1521 (s), 3210 (m).
1H NMR (300 MHz, DMSO-d6): = 7.30–8.36 (m, 9 H, ArH), 9.02
IR (KBr): 840 (m), 890 (m), 955 (m), 1080 (s), 1190 (w), 1290 (s),
1450 (s), 1495 (s), 1610 (s), 3190 (m), 3295 (s) cm–1.
(s, 2JSeH = 42.5 Hz, 1 H, 5-H, Hetar), 13.80 (br s, OH).
1H NMR (300 MHz, DMSO-d6): = 7.43–8.34 (m, 10 H, ArH),
8.81 (s, 1 H, NH), 9.06 (s, 2JSeH = 21.1 Hz, 1 H, 5-H, Hetar), 13.96
(s, 2 H, NH2).
13C NMR (75 MHz, DMSO-d6):
126.48, 128.90, 130.92, 131.18, 134.87, 141.51, 150.35, 154.06,
156.69.
= 120.29, 123.02, 125.52,
13C NMR (75 MHz, DMSO-d6):
127.74, 128.93, 129.49, 129.85, 130.08, 137.55, 146.18, 155.67,
167.10, 178.82.
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
808.5.
MS (70 eV): m/z = 386 (36) [M+], 331 (17), 298 (72), 277 (37), 217
(11), 191 (9), 182 (24), 169 (27), 116 (16), 89 (23), 102 (100), 89
(23), 77 (42), 61 (43), 51 (16), 28 (35).
= 125.40, 125.58, 126.33,
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
642.1.
MS (70 eV): m/z = 373 (43) [M+], 343 (15), 297 (5), 217 (6), 195
(5), 182 (27), 180 (13), 102 (100), 77 (17), 51 (7), 28 (21).
=
=
Anal. Calcd for C16H11N3O3Se (372.22): C, 51.63; H, 2.98; N,
11.33. Found: C, 51.58; H, 2.76; N, 11.33.
Synthesis of 2-Arylcarbamoyl-4-phenyl-1,3-selenazoles (8);
General Procedure
Anal. Calcd for C17H14N4SSe (385.35): C, 52.99; H, 3.66; N, 14.54.
Found: C, 52.63; H, 3.27; N, 14.51.
The ketoxime 7 (5.0 mmol) was dissolved in anhyd Et2O (30 mL)
and an excess of PCl5 (3.00 g) was subsequently added. The mixture
was refluxed with stirring for 30 min. Et2O was removed by distil-
lation and the residue was washed with H2O and recrystallized from
EtOH to give 8.
Synthesis of Ketoximes (7); General Procedure
A water solution (5 mL) of hydroxyamine hydrochloride (0.70 g,
10.0 mmol) and NaOH (0.80 g, 20.0 mmol) was poured into an
EtOH solution (70 mL) of 4 and the solution was subsequently re-
fluxed 1 h. After cooling to 20 °C, the solution was poured into ice
water (100 mL) and was neutralized with an aq solution of HCl acid
(2 M) to give a precipitate. The latter was filtered off and recrystal-
lized (EtOH) to give 7.
2-Phenylcarbamoyl-4-phenyl-1,3-selenazole (8a)
Yield: 1.30 g, 80%; yellow needles; mp 140–141 °C.
IR (KBr): 880 (m) 901 (w), 1030 (w), 1066 (w), 1089 (w), 1198 (w),
1305 (s), 1575 (s), 1685 (s), 3080 (w) cm–1.
1H NMR (300 MHz, CDCl3): = 7.02–7.94 (m, 10 H, ArH), 8.32
Phenyl-(4-phenyl-1,3-selenazol-2-yl)-ketoxime (7a)
Yield: 1.40 g, 87%; beige needles; mp 160–162 °C.
(s, 2JSeH = 45.6 Hz, 1 H, 5-H,), 9.05 (br s, 1 H, NH).
13C NMR (50 MHz, CDCl3): = 119.83 (5-C, Hetar), 124.77 (CH,
Ar), 125.39 (CH, Ar), 126.62 (CH, Ar), 128.48 (CH, Ar), 128.84
(CH, Ar), 129.15 (CH, Ar), 134.51 (Ar), 137.01 (Ar), 157.15 (4-C,
Hetar), 158.53 (2-C, Hetar), 170.91 (C=O).
MS (70 eV): m/z = 328 (56) [M+], 326 (29), 286 (11), 234 (3), 209
(14), 182 (20), 127 (5) 102 (100), 77 (10), 66 (19), 28 (2).
IR (KBr): 890 (m), 910 (s), 990 (m), 1020 (w), 1060 (w), 1080 (w),
1145 (w), 1331 (m), 1466 (m), 1491 (m) cm–1.
1H NMR (300 MHz, CDCl3): = 7.38–7.98 (m, 12 H, ArH, 5-H,
Hetar).
13C NMR (75 MHz, CDCl3): = 126.77, 128.74, 128.93, 129.28,
129.50, 130.81, 131.63, 133.63, 134.53, 158.76, 175.08, 184.60.
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 807.2.
Anal. Calcd for C16H12N2OSe (327.23): C, 58.73; H, 3.70; N, 8.56.
Found: C, 58.81; H, 3.82; N, 8.72.
MS (70 eV): m/z = 328 (81) [M+], 326 (40), 218 (11), 217 (11), 218
(13), 191 (6), 182 (27), 169 (19), 127 (6), 116 (14), 77 (38), 51 (26),
28 (6).
2-(4-Chlorophenylcarbamoyl)-4-phenyl-selenazole (8b)
Yield: 92%; colorless needles (EtOH); mp 198–199 °C.
IR (KBr): 820 (s), 900 (m), 1056 (s), 1101 (m), 1190 (w), 1236 (m),
1401 (s), 1500 (s), 1536 (s), 1601 (s), 1691 (s), 3115 (m), 3382 (s)
cm–1.
Anal. Calcd for C16H12N2OSe (327.22): C, 58.73; H, 3.69; N, 8.56.
Found: C, 59.00; H, 3.40; N, 8.69.
1H NMR (300 MHz, CDCl3): = 7.35–7.95 (m, 9 H, ArH), 8.51 (s,
4-Chlorophenyl-(4-phenyl-selenazol-2-yl)-ketoxime (7b)
Yield: 77%; colorless needles (C6H6); mp 196–198.5 °C.
2JSeH = 45.6 Hz, 1 H, 5-H, Hetar), 9.10 (br s, 1 H, NH).
13C NMR (75 Hz, CDCl3): = 121.09 (5-C, Hetar), 125.65 (Ar),
126.68 (Ar), 128.62 (Ar), 128.92 (Ar), 129.26 (Ar), 129.86 (Ar),
134.50 (Ar), 135.65 (Ar), 157.37 (4-C, Hetar), 158.61 (2-C, Hetar),
170.59 (C=O).
IR (KBr): 831 (s), 881 (s), 905 (s), 981 (s), 1015 (m), 1100 (s), 1136
(m), 1280 (m), 1321 (m), 1401 (m), 1451 (m), 1491 (s), 1602 (m),
3200 (m) cm–1.
1H NMR (300 MHz, DMSO-d6): = 7.32–7.90 (m, 10 H, ArH),
8.95 (s, 2JSeH = 42.3 Hz, 1 H, 5-H, Hetar).
77Se NMR (38.18 MHz, CDCl3, 60% Me2Se in CDCl3): = 766.97.
13C NMR (75 MHz, DMSO-d6):
129.22, 131.82, 133.94, 134.18, 135.03, 135.20, 151.08, 151.19,
157.37.
= 125.48, 126.67, 128.36,
MS (70 eV): m/z = 361 (35) [M+], 327 (5), 236 (7), 209 (12), 182
(11), 127 (5), 102 (100), 77 (5), 28 (2).
Synthesis 2004, No. 1, 97–105 © Thieme Stuttgart · New York

PAPER
Synthesis and Reactivity of 2-Acyl-1,3-selenazoles
105
Anal. Calcd for C16H11N2OClSe (361.68): C, 53.14; H, 3.07; N,
7.74. Found: C, 53.21; H, 3.12; N, 7.95.
References
(1) (a) Goldstein, B. M.; Kennedy, S. D.; Hennen, W. J. J. Am.
Chem. Soc. 1990, 112, 8265; and references cited therein.
(b) Shafiee, A.; Khashayarmanesh, Z.; Kamal, F. J. Sci.,
Islamic Repub. Iran 1990, 1, 11. (c) Shafiee, A.; Shafaati,
A.; Khamench, B. H. J. Heterocycl. Chem. 1989, 26, 709.
(d) For cancerostatic activity of 1,3-selenazoles
Synthesis of 2-Amino-5-phenyl-1,3-selenazole (9); Typical Pro-
cedure
An EtOH solution (30 mL) of selenourea (1.23 g, 10.0 mmol) and
phenacyl bromide (1.99 g, 10.0 mmol) was briefly refluxed and the
hot solution was filtered. After cooling of the filtrate to 20 °C, an aq
solution of NH3 (2 mL, concd) and H2O (20 mL) were added. The
precipitate was recrystallized from EtOH–H2O to give 9 as colorless
needles (1.94 g, 87%); mp 131–132 °C.
see:Srivastava, P. C.; Robins, R. K. J. Med. Chem. 1983, 26,
445. (e) Also see:Shafiee, A.; Mazloumi, A.; Cohen, V. J. J.
Heterocycl. Chem. 1979, 16, 1563.
(2) (a) Larsen, R. 1,3-Selenazoles In Comprehensive
Heterocyclic Chemistry II, Vol. 3; Katritzky, A.; Rees, C.
W.; Scriven, E. F. V., Eds.; Elsevier Science: Oxford, 1996,
Chap. 8. (b) Wirth, T. In Modern Developments in Organic
Synthesis, Organoselenium Chemistry; Springer: Berlin,
2000. (c) Koketsu, M.; Nada, F.; Ishihara, H. Synthesis 2002,
195. (d) Kaminski, R.; Glass, R. S.; Skowronska, A.
Synthesis 2001, 1308. (e) Ishihara, H.; Koketsu, M.; Fukuta,
Y.; Nada, F. J. Am. Chem. Soc. 2001, 123, 8408.
(f) Koketsu, M.; Fukuta, Y.; Ishihara, H. Tetrahedron Lett.
2001, 42, 6333. (g) Zhang, P.-F.; Chen, Z.-C. Synthesis
2000, 9, 1219. (h) Maeda, H.; Kambe, N.; Sonoda, N.;
Fujiwara, S.-I.; Sini-ike, T. Tetrahedron 1997, 53, 13667.
(i) Lai, L.-L.; Reid, D. H. Synthesis 1993, 870. (j) Ogawa,
A.; Miyaka, J.; Karasaki, Y.; Murai, S.; Sonoda, N. J. Org.
Chem. 1985, 50, 384. (k) Cohen, V. J. Synthesis 1978, 668.
(3) Geisler, K.; Pfeiffer, W.-D.; Müller, C.; Nobst, E.; Bulka, E.;
Langer, P. Synthesis 2003, 1215.
(4) 4-Methylselenazole was prepared by reaction of HCN, H2Se
and chloroacetone in 3% yield: Haginiwa, J. Yakugaku
Zasshi 1948, 68, 191.
(5) The reaction of ethyl iso-cyanoacetate with iso-
selenocyanates is limited to the synthesis of 4,5-
disubstituted and arylamino substituted selenazoles:Maeda,
H.; Kambe, N.; Sonoda, N.; Fujiwara, S.-I.; Sini-ike, T.
Tetrahedron 1997, 53, 13667; and references cited therein.
(6) Geisler, K.; Künzler, A.; Bulka, E.; Pfeiffer, W.-D.; Langer,
P. Synlett 2003, 1195.
IR (KBr): 825 (s), 900 (m), 1198 (m), 1325 (s), 1571 (s), 1608 (s),
1665 (s), 3130 (m), 3376 (m), 3478 (m) cm–1.
1H NMR (300 MHz, DMSO-d6): = 7.41–7.69 (m, 6 H, ArH, 5-H,
Hetar), 9.00 (br s, NH2).
13C NMR (75 MHz, DMSO-d6):
= 126.02, 129.13, 129.27,
130.12, 139.29, 174.22, 201.14.
77Se NMR (38.18 MHz, DMSO-d6, 60% Me2Se in CDCl3):
=
556.4.
MS (70 eV): m/z = 224 (86) [M+], 182 (82), 102 (100), 80 (19), 77
(14), 51 (13), 28 (26).
Anal. Calcd for C9H8N2Se1 (223.14): C, 48.45; H, 3.61; N, 12.55.
Found: C, 48.51; H, 3.72; N, 12.62.
Synthesis of 2-Benzoylamino-4-phenyl-selenazole (10); Typical
Procedure
A pyridine solution (20 mL) of 9 (1.10 g, 5.0 mmol) and of benzoyl
chloride (0.70 g, 5.0 mmol) was refluxed for 15 min. After cooling
to 20 °C, the mixture was poured into ice water to give a crystalline
precipitate. The latter was crystallized from EtOH to give 10 as col-
orless needles (0.95 g, 59%); mp 165.5 °C.
IR (KBr): 901 (w), 1030 (w), 1066 (w), 1089 (w), 1198 (w), 1305
(s), 1575 (s), 1685 (s), 3080 (w) cm–1.
1H NMR (200 MHz, CDCl3): = 2.17 (s, 1 H, NH), 7.31–7.78 (m,
10 H, ArH), 7.82 (s, 2JSeH = 47 Hz, 1 H, 5-H, Hetar).
13C NMR (50 MHz, CDCl3): = 113.26 (5-C, Hetar), 126.22 (CH,
Ar), 127.30 (CH, Ar), 127.71 (CH, Ar), 128.58 (CH, Ar), 128.73
(CH, Ar), 131.78, 132.72, 135.23, 150.61, 160.75 (C), 165.41
(C=O).
MS (70eV): m/z = 328 (34) [M+], 326 (17), 182 (6), 105 (100), 77
(75), 51 (16), 28 (2).
(7) For 2-benzoyl-1,3-benzoselenazole, see: Mbuyi, M.; Evers,
M.; Tihange, G.; Luxen, A.; Christiaens, L. Tetrahedron
Lett. 1983, 5873.
(8) Geisler, K.; Jacobs, A.; Künzler, A.; Mattes, M.; Girrleit, I.;
Zimmermann, B.; Bulka, E.; Pfeiffer, W.-D.; Langer, P.
Synlett 2002, 1983.
(9) 2-Unsubstituted 1,3-thiazoles have been prepared by
decarboxylation of 1,3-thiazolyl-2-carboxylic acids, see for
example: (a) Sarodnick, G.; Kempter, G. Pharmazie 1983,
38, 829. (b) Pirotte, B.; Delarge, J. J. Chem. Res., Miniprint
1990, 7, 1634. (c) Strehlke, P. Chem. Ber. 1973, 106, 721.
(d) Sarodnick, G.; Kempter, G. Z. Chem. 1979, 19, 21. (e)
For the hydroxide mediated fragmentation of
Anal. Calcd for C16H12N2OSe (327.23): C, 58.73; H, 3.70; N, 8.56.
Found: C, 58.81; H, 3.82; N, 8.72.
Acknowledgment
Financial support from the Deutsche Forschungsgemeinschaft is
gratefully acknowledged.
benzophenones, see: Montagne, P. I. Recl. Trav. Chim.
Pays-Bas 1908, 27, 327.
(10) (a) Dunbar, R. E.; Painter, E. P. J. Am. Chem. Soc. 1947, 69,
1833. (b) Hope, H. Acta Chem. Scand. 1964, 18, 1800.
(c) Badillo, R.; Breccia, R. Ric. Sci. 1966, 36, 335.
Synthesis 2004, No. 1, 97–105 © Thieme Stuttgart · New York