Synthesis of 1,3-selenazol-2(3H)-imines

Article abstract of DOI:10.1002/hlca.200900452

The reaction of N,N′-diarylselenoureas 16 with phenacyl bromide in EtOH under reflux, followed by treatment with NH₃ , gave N,3-diaryl-4-phenyl-1,3-selenazol-2(3H)-imines 13 in high yields (Scheme 2). A reaction mechanism via formation of the corresponding Se-(benzoylmethyl) isoselenoureas 18 and subsequent cyclocondensation is proposed (Scheme 3). The N,N′-diarylselenoureas 16 were conveniently prepared by the reaction of aryl isoselenocyanates 15 with 4-substituted anilines. The structures of 13a and 13c were established by X-ray crystallography.

Full text of DOI:10.1002/hlca.200900452

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Synthesis of 1,3-Selenazol-2(3H)-imines
by Plamen K. Atanassov1), Anthony Linden, and Heinz Heimgartner*
Organisch-Chemisches Institut der Universitꢀt Zꢁrich, Winterthurerstrasse 190, CH-8057 Zꢁrich
(phone: þ 41-44-635 4282; fax: þ 41-44-635 6812; e-mail: heimgart@oci.uzh.ch)
Dedicated to Prof. Ludmila L. Rodina, Saint Petersburg, on the occasion of her 70th birthday
The reaction of N,N’-diarylselenoureas 16 with phenacyl bromide in EtOH under reflux, followed by
treatment with NH3, gave N,3-diaryl-4-phenyl-1,3-selenazol-2(3H)-imines 13 in high yields (Scheme 2).
A reaction mechanism via formation of the corresponding Se-(benzoylmethyl)isoselenoureas 18 and
subsequent cyclocondensation is proposed (Scheme 3). The N,N’-diarylselenoureas 16 were conveniently
prepared by the reaction of aryl isoselenocyanates 15 with 4-substituted anilines. The structures of 13a
and 13c were established by X-ray crystallography.
Introduction. – Since the discovery of the importance of Se as a microelement in
bacteria and animals [1], and the function of the selenoenzyme glutathione peroxidase
(GPx) as an antioxidant [2], the interest in organoselenium compounds has increased
significantly. As a result, a large series of organoselenium compounds was prepared as
GPx mimics, e.g., diorgano di- and triselenides 1 and 2 [3 – 5], and selenaheterocycles
3 – 6 [6][7]. In recent years, isoselenocyanates have been shown to be useful building
blocks for the synthesis of Se-containing heterocycles [8].
As continuation of our studies toward the use of isoselenocyanates in the synthesis
of 1,3-selenazole derivatives [9 – 14] and with the aim of preparing 1,3-selenazol-
1
)
Postdoctoral stay at the University of Zꢁrich (04. – 12.2004).
ꢂ 2010 Verlag Helvetica Chimica Acta AG, Zꢁrich

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2(3H)-imines, we investigated the reaction of selenourea derivatives, which are easily
accessible from isoselenocyanates, with phenacyl bromide. Whereas the analogous
synthesis of 1,3-thiazol-2(3H)-imines 9 via the reaction of thioureas 7 with phenacyl
bromides 8, i.e., the Hantzsch condensation reaction [15], is well-known [16 – 21]
(Scheme 1), no synthesis of the corresponding 1,3-selenazol-2(3H)-imines has been
reported so far.
Scheme 1
Very recently, Koketsu et al. and other groups reported on the synthesis of some 1,3-
selenazolidine-2-imines [22 – 25]. For example, N,N’-diisopropylselenourea (10) and 2-
bromo-2-methylpropanoyl bromide (11) in pyridine led to the 2-imino-1,3-selenazo-
lidin-4-one 12, the structure of which has been determined by X-ray crystallography
[22] (Scheme 1).
Here, we describe the synthesis of some N,3-diaryl-4-phenyl-1,3-selenazol-2(3H)-
imines 13 in a two step reaction from anilines 14, aryl isoselenocyanates 15, and
phenacyl bromide.
Results and Discussion. – The selenoureas 16 were prepared conveniently
according to the protocol reported in [26]. The reaction of 4-bromophenyl and 4-
chlorophenyl isoselenocyanate (15a and 15b, resp.) with 4-substituted anilines 14 in
tolouene in the presence of a catalytic amount of Et3N gave 16a – 16f in high yields as
crystalline materials (Scheme 2). Then, the solution of equimolar amounts of 16 and
phenacyl bromide in EtOH was heated to reflux for 2 h. The cooled mixture was
poured into H2O and treated with aqueous NH3 to convert the formed hydrobromides
17 to the free 1,3-selenazol-2(3H)-imines 13 (Scheme 2). The products were isolated in
good yield as colorless solids.
The structures of the products were determined on the basis of the spectroscopic
and analytical data, and, in the cases of 13a and 13c, they were established by X-ray
crystallography (Fig.). In both cases, the five-membered heterocycle is planar, but
none of the aryl rings is coplanar with it. In 13c, the 4-(dimethylamino)phenyl residue is
attached to the N-atom of the 1,3-thiazole ring, and the 4-bromophenyl moiety is
located at the imine N-atom.
According to the NMR spectra, only one product was formed in the reactions with
16a – 16c and 16e, i.e., the formation of 13b, 13c, and 13e occurred regioselectively. On
the other hand, the products of the reaction with 16d and 16f consisted of a ca. 4 :1

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397
Scheme 2
Figure. ORTEP Plot [27] of the molecular structure of 13a and 13c (50% probability ellipsoids, arbitrary
numbering of the atoms)
1
mixture of two isomeric compounds. For example, the H-NMR spectrum of the
product from 16d and phenacyl bromide showed singlets at 6.37 and 6.41 ppm for
HꢀC(5), and 2.27 and 2.32 ppm for Me, each with an intensity ratio of ca. 4 :1. We
assigned the structures 13d and 13d’ to these products.
Based on the presented results and in analogy to the Hantzsch thiazole synthesis, we
propose the following reaction mechanism (Scheme 3): nucleophilic substitution of Br
in phenacyl bromide by the Se-atom of selenourea 16 leads to the isoselenourea

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Scheme 3
derivative 18, which subsequently undergoes a cyclocondensation to give the hydro-
bromide of 13 (cf. [17]). The plausible intermediate is 19, formed via nucleophilic
addition of an N-atom of 18 onto the C¼O group.
In the case of 18c, the cyclization occurs selectively via the more nucleophilic N-
atom, bearing the 4-(dimethylamino)phenyl residue. The same selectivity was observed
in the cases of the reactions with 16b and 16e with a 4-methoxyphenyl substituent. The
formation of two isomers of type 13d and 13dꢀ in the reaction with 16d and 16f,
respectively, which bear a 4-methylphenyl substituent in addition to a 4-bromo- or 4-
chlorophenyl residue, can be explained with the smaller difference of the nucleophi-
licity of the two N-atoms due to the lower electron-donating properties of the Me group
in comparison with the Me2N and MeO groups.
In conclusion, a convenient synthesis of the little known 1,3-selenazol-2(3H)-imines
from diarylselenoureas and phenacyl bromide was developed. This approach can easily
be applied for the preparation of differently substituted analogues.
We thank the analytical units of our institute for spectra and analyses. Financial support of the work
by the Swiss National Science Foundation and F. Hoffmann-La Roche AG, Basel, is gratefully
acknowledged.

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Experimental Part
1. General. See [28]. M.p.: Mettler-FP-5 or Bꢀchi B-450 apparatus; uncorrected. IR Spectra: Perkin-
1
Elmer-781 or Perkin-Elmer-1600-FT-IR spectrophotometer. H- and 13C-NMR spectra: Bruker-AC-300
or Bruker-ARX-300 instrument (300 and 75.5 MHz, resp.), in (D6)DMSO or CDCl3; multiplicity of C-
atoms from DEPT spectra. MS: Finnigan MAT-90 or Finnigan SSQ-700 instrument (CI (NH3) or ESI).
Elemental analyses were performed by the Mikroanalytisches Laboratorium des Organisch-chemischen
Instituts der Universitꢀt Zꢁrich.
2. Starting Materials. 4-Bromophenyl isoselenocyanate (15a) and 4-chlorophenyl isoselenocyanate
(15b) were prepared according to the protocol described in [29], and N,N’-diarylselenoureas 16 were
prepared according to [26]. All other chemicals were commercially available.
3. Synthesis of N,N’-Selenoureas 16. 3.1. N,N’-Bis(4-bromophenyl)selenourea (16a) [30]. From 1.05 g
(4 mmol) of 15a and 0.69 g (4 mmol) of 4-bromoaniline (14a): 1.6 g (92%) of 16a. M.p. 222.6 – 224.08
(toluene). Creamy solid. IR: 3175s, 3021s, 2998s, 2832m, 1580m, 1552s, 1524s, 1485s, 1401m, 1333s, 1310s,
1
1271m, 1254m, 1236m, 1217m, 1171w, 1094w, 1072s, 1016s, 920m, 851m, 827s. H-NMR ((D6)DMSO):
10.25 (s, 2 NH); 7.52, 7.38 (AA’BB’, JAB ¼ 8.8, 8 arom. H). 13C-NMR ((D6)DMSO): 179.1 (s, CSe); 138.9,
117.5 (2s, 4 arom. C); 131.3, 126.7 (2d, 8 arom. CH). CI-MS: 437 (18), 435 (38, [M þ 1]þ), 433 (30), 431
(12), 357 (41), 356 (17), 355 (100), 354 (17), 352 (80). Anal. calc. for C13H10Br2N2Se (433.00): C 36.06, H
2.33, N 6.47; found: C 35.52, H 2.31, N 6.39.
3.2. N-(4-Bromophenyl)-N’-(4-methoxyphenyl)selenourea (16b). From 0.5 g (1.9 mmol) of 15a and
0.23 g (1.9 mmol) of 4-methoxyaniline (14b): 0.57 g (80.3%) of 16b. M.p. 188.8 – 190.38 (CH2Cl2/hexane).
IR: 3175s, 3000s, 2836m, 1608m, 1587w, 1553s, 1527m, 1505s, 1482m, 1463m, 1339s, 1297s, 1247s, 1218m,
1180m, 1166m, 1103m, 1068m, 1031m, 1015m, 921w, 851w, 833s. 1H-NMR ((D6)DMSO): 10.08, 9.94 (2s,
2 NH); 7.50, 7.37 (AA’BB’, JAB ¼ 8.8, 4 arom. H); 7.26, 6.9l (AA’BB’, JAB ¼ 8.9, 4 arom. H); 3.75 (s, MeO).
13C-NMR ((D6)DMSO): 178.8 (s, CSe); 157.0, 139.2, 132.1, 117.2 (4s, 4 arom. C); 131.1, 126.8, 126.6, 113.7
(4d, 8 arom. CH); 55.1 (q, MeO). CI-MS: 387 (3), 385 (4, [M þ 1]þ), 383 (2), 307 (41), 306 (17), 305
(100), 304 (13), 303 (60). Anal. calc. for C14H13BrN2OSe (384.13): C 43.77, H 3.41, N 7.29; found: C 43.83,
H 3.50, N 7.34.
3.3. N-(4-Bromophenyl)-N’-[4-(dimethylamino)phenyl]selenourea (16c). From 1.0 g (3.83 mmol) of
15a and 0.52 g (3.82 mmol) of 4-(dimethylamino)aniline (14c): 1.3 g (86%) of 16c. M.p. 171.3 – 174.08
(CH2Cl2/hexane). IR: 3172s, 3004s, 2884m, 2842m, 2800m, l611m, 1575w, 1551s, 1531s, 1515s, 1483m,
1444w, 1397w, 1329s, 1309s, 1247m, 1224m, 1184w, 1165w, 1128w, 1097w, 1064m, 1012m, 945m, 920m, 819s.
1H-NMR ((D6)DMSO): 10.01, 9.74 (2s, 2 NH); 7.48, 7.37 (AA’BB’, JAB ¼ 8.9, 4 arom. H); 7.13, 6.69
(AA’BB’, JAB ¼ 8.9, 4 arom. H); 2.89 (s, 2 Me). 13C-NMR ((D6)DMSO): 178.2 (s, CSe); 148.6, 139.4,
127.9, 117.1 (4s, 4 arom. C); 131.0, 126.9, 126.1, 112.2 (4d, 8 arom. CH); 40.1 (q, 2 Me). ESI-MS: 400 (100),
398 (86, [M þ 1]þ), 396 (48). Anal. calc. for C15H16BrN3Se (397.17): C 45.36, H 4.06, N 10.58; found: C
45.49, H 4.12, N 10.60.
3.4. N-(4-Bromophenyl)-N’-(4-methylphenyl)selenourea (16d). From 0.5 g (1.9 mmol) of 15a and
0.2 g (1.9 mmol) of 4-methylaniline (14d): 0.6 g (88.2%) of 16d. M.p. 195.2 – 197.0 (CH2Cl2/hexane). IR:
3167s, 3001s, 2919w, 2832w, 1581m, 1551s, 1530m, 1506m, 1484s, 1398w, 1380w, 1335s, 1238m, 1219m,
1
1175w, 1106w, 1098w, 1068m, 1014s, 921w, 844w, 822s. H-NMR ((D6)DMSO): 10.25, 10.10 (2s, 2 NH);
7.58, 7.45 (AA’BB’, JAB ¼ 8.8, 4 arom. H); 7.33, 7.22 (AA’BB’, JAB ¼ 8.3, 4 arom. H); 2.36 (s, Me). 13C-NMR
((D6)DMSO): 178.6 (s, CSe); 139.2, 136.7, 134.6, 117.2 (4s, 4 arom. C); 131.1, 129.0, 126.7, 124.6 (4d, 8
arom. CH); 20.4 (q, Me). CI-MS: 371 (4), 369 (6, [M þ 1]þ), 367 (3), 291 (37), 290 (16), 289 (100), 288
(14), 287 (66). Anal. calc. for C14H13BrN2Se (368.13): C 45.68, H, 3.56, N 7.61; found: C 45.60, H 3.64, N
7.60.
3.5. N-(4-Chlorophenyl)-N’-(4-methoxyphenyl)selenourea (16e). From 0.7 g (3.2 mmol) of 15b and
0.4 g (3.2 mmol) of 14b: 1.0 g (90.9%) of 16e. M.p. 187.9 – 189.18 (CH2Cl2/hexane). IR: 3177s, 3001s,
2836m, 1609m, 1587w, 1554s, 1525m, 1505s, 1486m, 1463m, 1441w, 1401w, 1336s, 1297s, 1248s, 1218m,
1
1180m, 1166m, 1102m, 1090m, 1031m, 1018m, 922w, 852w, 834s, 821m. H-NMR ((D6)DMSO): 10.07,
9.94 (2s, 2 NH); 7.42, 7.38 (AA’BB’, JAB ¼ 8.9, 4 arom. H); 7.26, 6.91 (AA’BB’, JAB ¼ 8.9, 4 arom. H); 3.75
(s, Me). 13C-NMR ((D6)DMSO): 178.8 (s, CSe); 157.0, 138.7, 132.1, 129.0 (4s, 4 arom. C); 128.1, 126.6,
126.5, 113.7 (4d, 8 arom. CH); 55.1 (q, Me). CI-MS: 343 (1), 341 (3, [M þ 1]þ), 339 (1), 263 (14), 262

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(11), 261 (73), 260 (18), 259 (100). Anal. calc. for C14H13ClN2OSe (339.68): C 49.50, H 3.86, N 8.25;
found: C 49.68, H 3.97, N 8.32.
3.6. N-(4-Chlorophenyl)-N’-(4-methylphenyl)selenourea (16f). From 0.7 g (3.2 mmol) of 15b and
0.34 g (3.2 mmol) of 14d: 0.9 g (88.2%) of 16f. M.p. 195.2 – 195.98 (CH2Cl2/hexane). IR: 3172s, 3002s,
2921m, 2832w, 1584m, 1553s, 1506m, 1489m, 1403w, 1380w, 1332s, 1238m, 1220w, 1175w, 1090s, 1017m,
921w, 849w, 824s. 1H-NMR ((D6)DMSO): 10.42, 10.29 (2s, 2 NH); 7.69, 7.62 (AA’BB’, JAB ¼ 8.9, 4 arom.
H); 7.52, 7.41 (AA’BB’, JAB ¼ 8.3, 4 arom. H); 2.54 (s, Me). 13C-NMR ((D6)DMSO): 178.7 (s, CSe); 138.7,
136.7, 134.6 (3s, 4 arom. C); 129.0, 128.2, 126.4, 124.6 (4d, 8 arom. CH); 20.4 (q, Me). CI-MS: 327 (3), 325
(5, [M þ 1]þ), 323 (3), 247 (14), 246 (12), 245 (74), 244 (19), 243 (100). Anal. calc. for C14H13ClN2Se
(323.68): C 51.95, H 4.05, N 8.65; found: C 51.99, H 4.09, N 8.75.
4. Reaction of N,N’-Diarylselenoureas 16 with Phenacyl Bromide. General Procedure. Approximately
2.5 ml of abs. EtOH were added to a mixture of equimolecular amounts (1 – 2 mmol) of 16 and phenacyl
bromide. The mixture was stirred for 2 h under reflux. Then, the soln. was cooled to r.t., poured into cold
H2O, and treated with aq. NH3. The solid obtained was filtered and dried (MgSO4). The mother liquor
was concentrated in vacuo, MeOH was added, and the white solid formed was again filtered and dried.
4.1. N,3-Bis(4-bromophenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13a). From 0.73 g (1.7 mmol) of
16a and 0.33 g (1.7 mmol) of phenacyl bromide: 0.7 g (77.8%) of 13a. M.p. 193.1 – 194.48 (CHCl3/
MeOH). White solid. IR: 3121w, 3103w, 3084w, 3055w, 1623s, 1574m, 1556m, 1484m, 1475m, 1445w,
1396w, 1349m, 1298m, 1249m, 1144m, 1093w, 1062m, 1013m, 1004m, 919m, 868m, 825m. 1H-NMR
(CDCl3): 7.44 – 7.41 (m, 4 arom. H); 7.40 – 7.22 (m, 3 arom. H); 7.21 – 7.06 (m, 4 arom. H); 6.94 (BB’ of
AA’BB’, JAB ¼ 8.6, 2 arom. H); 6.43 (s, HꢀC(5)). 13C-NMR (CDCl3): 141.4, 137.5, 132.4, 128.4, 121.8,
117.2 (6s, 5 arom. C, C(2), C(4)); 132.8, 132.2, 130.5, 128.61, 128.58, 128.4, 123.2 (7d, 13 arom. CH); 98.0
(d, C(5)). CI-MS: 539 (7), 538 (12), 537 (52), 536 (27), 535 (100, [M þ 1]þ), 534 (32), 533 (83), 532 (25),
531 (35), 530 (10). Anal. calc. for C21H14Br2N2Se (533.12): C 47.31, H 2.65, N 5.25; found: C 47.12, H 2.80,
N 5.24.
Suitable crystals of 13a for the X-ray crystal structure determination were obtained from Et2O by
slow evaporation of the solvent at 58.
4.2. N-(4-Bromophenyl)-3-(4-methoxyphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13b). From
0.3 g (0.78 mmol) of 16b, 0.15 g (0.78 mmol) of phenacyl bromide, and 15 – 20 ml of EtOH: 0.35 g
(92%) of 13b. M.p. 214.9 – 215.38 (CH2Cl2/MeOH). IR: 3097w, 3055w, 3010w, 2958w, 2928w, 2901w,
2830w, 1614s, 1602s, 1573s, 1557m, 1509s, 1490w, 1479s, 1462w, 1449w, 1434w, 1347m, 1300m, 1285w, 1248s,
1146s, 1096w, 1067m, 1028m, 1006m, 919w, 871m, 830m. 1H-NMR (CDCl3): 7.41, 6.96 (AA’,BB’, JAB ¼ 8.4,
4 arom. H); 7.25 – 7.08 (m, 7 arom. H); 6.80 (BB’ of AA’BB’, JAB ¼ 8.7, 2 arom. H); 6.41 (s, HꢀC(5)); 3.74
(s, MeO). 13C-NMR (CDCl3): 158.8, 142.1, 131.1, 116.7 (4s, 5 arom. C, C(2), C(4)); 132.6, 129.8, 128.6,
128.3, 128.0, 123.4, 114.3 (7d, 13 arom. CH); 97.5 (d, C(5)); 55.2 (q, MeO). CI-MS: 489 (14), 488 (20), 487
(78), 486 (28), 485 (100, [M þ l]þ), 484 (26), 483 (46), 482 (15), 481 (14). Anal. calc. for C22H17BrN2OSe
(484.25): C 54.57, H 3.54, N 5.78; found: C 54.15, H 3.59, N 5.75.
4.3. N-(4-Bromophenyl)-3-[4-(dimethylamino)phenyl]-4-phenyl-1,3-selenazol-2(3H)-imine (13c).
From 0.6 g (1.5 mmol) of 16c and 0.3 g (1.5 mmol) of phenacyl bromide: 0.55 g (73.3%) of 13c. M.p.
209.3 – 212.58 (CH2Cl2/MeOH). IR: 3106w, 2889w, 2861w, 2817w, 1608s, 1571s, 1557m, 1528s, 1489m,
1475s, 1443m, 1374w, 1338s, 1316w, 1289m, 1248m, 1232m, 1191w, 1138s, 1062s, 1000m, 918w, 860m, 825m,
809m. 1H-NMR (CDCl3): 7.40, 6.89 (AA’BB’, JAB ¼ 8.7, 4 arom. H); 7.26 – 7.04 (m, 7 arom. H); 6.63 (BB’
of AA’BB’, JAB ¼ 8.8, 2 arom. H); 6.29 (s, HꢀC(5)); 2.90 (s, 2 Me). 13C-NMR (CDCl3): 143.1, 133.9, 123.1,
116.2 (4s, 5 arom. C, C(2), C(5)); 133.3, 132.6, 129.5, 128.6, 128.5, 128.0, 123.2 (7d, 13 arom. CH); 95.7 (d,
C(5)); 40.7 (q, 2 Me). ESI-MS: 500 (46), 498 (100, [M þ 1]þ), 496 (40), 494 (24). Anal. calc. for
C23H20BrN3Se (497.29): C 55.55, H 4.05, N 8.45; found: C 55.73, H 4.08, N 8.38.
Suitable crystals of 13c for the X-ray crystal structure determination were obtained from Et2O by
slow evaporation of the solvent at 58.
5.4. N-(4-Bromophenyl)-3-(4-methylphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13d) and 3-(4-
Bromophenyl)-N-(4-methylphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13d’). From 0.3 g (0.81 mmol)
of 16d and 0.162 g (0.81 mmol) of phenacyl bromide: 0.3 g (78.9%) of 13d. M.p. 193.4 – 193.88 (CH2C12/
MeOH). IR: 3103w, 3051w, 3032w, 2918w, 1626s, 1604s, 1574m, 1508m, 1488m, 1478m, 1441w, 1350m,
1
1292m, 1246m, 1141m, 1065m, 1028w, 1006m, 916m, 868m, 826m. H-NMR (CDCl3; two isomers 4 :1):

Helvetica Chimica Acta – Vol. 93 (2010)
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7.40, 6.92 (AA’BB’, JAB ¼ 8.6, 4 arom. H); 7.30 – 7.05 (m, 9 arom. H); 6.41 (s, HꢀC(5), minor isomer); 6.37
(s, HꢀC(5), major isomer); 2.32 (s, Me, minor isomer); 2.27 (s, Me, major isomer). 13C-NMR (CDCl3):
142.0, 137.7, 135.9, 132.9, 116.8 (5s, 5 arom. C, C(2), C(4)); 132.5, 132.0, 130.4, 130.2, 129.6, 128.5, 128.4,
128.2, 128.1, 128.0, 123.2, 121.0 (12d, 13 arom. CH); 96.9 (d, C(5)); 21.2 (s, Me, major isomer); 21.0 (s, Me,
minor isomer). CI-MS: 473 (13), 472 (19), 471 (78), 470 (28), 469 (100, [M þ 1]þ), 468 (26), 467 (46),
466 (16), 465 (14). Anal. calc. for C22H17BrN2Se (468.25): C 56.43, H 3.66, N 5.98; found: C 56.33, H 3.64,
N 6.00.
4.5. N-(4-Chlorophenyl)-3-(4-methoxyphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13e). From 0.6 g
(1.77 mmol) of 16e and 0.35 g (1.76 mmol) of phenacyl bromide: 0.6 g (77.92%) of 13e. M.p. 200.0 –
200.78 (CH2Cl2/MeOH). IR: 3097w, 3052w, 3013w, 2956w, 2930w, 2903w, 2833w, 1614s, 1603s, 1577s,
1556m, 1509s, 1481s, 1463m, 1451m, 1442m, 1346m, 1309m, 1300m, 1285m, 1247s, 1168m, 1146s, 1087m,
1067m, 1029m, 1008m, 919w, 872m, 832s, 821m. 1H-NMR (CDCl3): 7.26, 6.97 (AA’BB’, JAB ¼ 8.7, 4 arom.
H); 7.19 – 7.10 (m, 7 arom. H); 6.79 (BB’ of AA’BB’, JAB ¼ 8.9, 2 arom. H); 6.35 (s, HꢀC(5)); 3.73 (s, Me).
13C-NMR (CDCl3): 158.8, 151.8, 142.0, 133.0, 131.4, 129.0 (6s, 5 arom. C, C(2), C(4)); 130.2, 130.0, 129.7,
128.7, 128.2, 128.1, 122.8, 114.3 (8d, 13 arom. C); 96.5 (d, C(5)); 55.3 (q, MeO). CI-MS: 445 (6), 444 (11),
443 (44), 442 (26), 441 (100, [M þ 1]þ), 440 (20), 439 (49), 438 (18), 437 (17). Anal. calc. for
C22H17ClN2OSe (439.80): C 60.08, H 3.90, N 6.37; found: C 60.01, H 3.95, N 6.38.
4.6. N-(4-Chlorophenyl)-3-(4-methylphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13f) and 3-(4-
Chlorophenyl)-N-(4-methylphenyl)-4-phenyl-1,3-selenazol-2(3H)-imine (13f’). From 0.5 g (1.5 mmol)
of 16f and 0.3 g (1.5 mmol) of phenacyl bromide: 0.6 g (92.3%) of 13f. M.p. 191.1 – 191.38 (CH2Cl2/
MeOH). IR: 3108w, 3051w, 3033w, 2918w, 2855w, 1630s, 1620s, 1606s, 1580s, 1509m, 1481s, 1441m, 1350m,
1307w, 1293m, 1246m, 1165w, 1141s, 1105w, 1087m, 1066m, 1028w, 1009m, 916m, 869m, 831m, 821m.
1H-NMR (CDCl3, 2 isomers 4 :1): 7.30 – 6.95 (m, 13 arom. H); 6.44 (s, HꢀC(5), minor isomer); 6.39 (s,
HꢀC(5), major isomer); 2.32 (s, Me, minor isomer); 2.27 (s, Me, major isomer). 13C-NMR (CDCl3):
142.1, 142.0, 137.5, 132.8 (4s, 5 arom. C, C(2), C(4)); 130.3, 130.2, 129.7, 129.3, 128.7, 128.6, 128.3, 128.1,
123.0, 121.4 (10d, 13 arom. H); 97.3 (d, C(5)); 21.2 (s, Me, major isomer); 21.0 (s, Me, minor isomer). CI-
MS: 429 (6), 428 (11), 427 (44), 426 (26), 425 (100, [M þ 1]þ), 424 (20), 423 (49), 422 (19), 421 (17).
Anal. calc. for C22H17ClN2Se (423.80): C 62.35, H 4.04, N 6.61; found: C 62.19, H 4.13, N 6.60.
5. X-Ray Crystal-Structure Determination of 13a and 13c (Table, and Figs. 1 and 2)2). All
measurements were performed on a Nonius KappaCCD diffractometer [31] using graphite-monochro-
mated MoKa radiation (l 0.71073 ꢃ) and an Oxford Cryosystems Cryostream 700 cooler. The data
collection and refinement parameters are given in the Table, and views of the molecules are shown in the
Figure. Data reduction was performed with HKL Denzo and Scalepack [32]. The intensities were
corrected for Lorentz and polarization effects, and absorption corrections based on the multi-scan
method [33] were applied. The structure of 13a was solved by direct methods using SIR92 [34], which
revealed the positions of all non-H-atoms. The structure of 13c was solved by heavy-atom Patterson
methods [35], which revealed the positions of the Br- and Se-atoms. All remaining non-H-atoms were
located in a Fourier expansion of the Patterson soln., which was performed by DIRDIF 94 [36]. The non-
H-atoms were refined anisotropically. All of the H-atoms were placed in geometrically calculated
positions and refined using a riding model where each H-atom was assigned a fixed isotropic
displacement parameter with a value equal to 1.2 Ueq of its parent atom (1.5 Ueq for Me groups). The
refinement of each structure was carried out on F2 using full-matrix least-squares procedures, which
minimized the function Sw(F2o – Fc2 )2). Corrections for secondary extinction were not applied. In the case
of 13c, several large peaks of residual electron density remain unaccounted for and cannot be associated
with any logical chemical species. It is presumed that they are artefacts caused by the inferior data quality.
Neutral atom scattering factors for non-H-atoms were taken from [37a], and the scattering factors for H-
atoms were taken from [38]. Anomalous dispersion effects were included in Fc [39]; the values for f’ and
f’’ were those of [37b]. The values of the mass-attenuation coefficients are those of [37c]. All calculations
were performed using the SHELXL97 [40] program.
2
)
CCDC-757788 and -757789 contain the supplementary crystallographic data for this article. These
data can be obtained free of charge from the Cambridge Crystallographic Data Centre via http://
www.ccdc.cam.ac.uk/data_request/cif.

402
Helvetica Chimica Acta – Vol. 93 (2010)
Table. Crystallographic Data for Compounds 13a and 13c
13a
13c
Crystallized from
Empirical formula
Formula weight
Et2O
C21H14Br2N2Se
533.06
Et2O
C23H20BrN3Se
497.24
Crystal color, habit
Crystal dimensions [mm]
Temperature [K]
Crystal system
colorless, needle
colorless, needle
0.02 ꢁ 0.05 ꢁ 0.27
160(1)
0.05 ꢁ 0.05 ꢁ 0.35
160(1)
monoclinic
P21/c
triclinic
¯
Space group
P1
Z
4
2
Reflections for cell determination
45874
64681
2q Range for cell determination [8]
4 – 50
4 – 55
Unit cell parameters a [ꢃ]
5.7698(2)
23.1139(8)
14.3302(5)
90
93.394(2)
90
1907.8(1)
1.856
6.176
5.9821(2)
10.9232(5)
15.9088(7)
100.029(2)
97.181(3)
99.019(3)
998.53(7)
1.654
b [ꢃ]
c [ꢃ]
a [8]
b [8]
g [8]
V [ꢃ3]
Dx [g cmꢀ1
]
m(MoKa) [mmꢀ1
Scan type
]
3.900
f and w
55
f and w
50
2q(max) [8]
Transmission factors (min; max)
Total reflections measured
Symmetry independent reflections
Reflections with I > 2s(I)
Reflections used in refinement
Parameters refined
0.522; 0.744
31960
3356
2501
3356
0.770; 0.928
22568
4556
3474
4556
235
255
Final R(F) [I > 2s(I) reflections]
0.0360
0.0769
0.0342; 1.1353
1.042
0.0812
0.2430
0.1645; 1.3205
1.089
wR(F2) (all data)
Weighting parameters [a; b]a)
Goodness of fit
Final Dmax/s
D1 (max; min) [e ꢃꢀ3
0.001
0.44; ꢀ 0.47
0.001
3.62; ꢀ 0.75
]
a) wꢀ1 ¼ s 2(F2o ) þ (aP)2 þ bP where P ¼ (Fo2 þ 2F2c )/3.
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Received December 16, 2009