Selenium-containing heterocycles from isoselenocyanates: Synthesis of 1H-5-selena-1,3,6-triazaaceanthrylene derivatives

Article abstract of DOI:10.1002/hlca.200390263

The reaction of aryl isoselenocyanates 8 with methyl 3-amino-4-chloro-1-ethylpyrrolo[3,2-c]quinoline-2-carboxylate (6) in boiling pyridine leads to tetracyclic selenaheterocycles of type 9 in high yield (Scheme 3). A reaction mechanism via an intermediate

Full text of DOI:10.1002/hlca.200390263

Helvetica Chimica Acta Vol. 86 (2003)
3235
Selenium-Containing Heterocycles from Isoselenocyanates:
Synthesis of 1H-5-Selena-1,3,6-triazaaceanthrylene Derivatives
by Plamen K. Atanassov1), Anthony Linden, and Heinz Heimgartner*
Organisch-chemisches Institut der Universit‰t Z¸rich, Winterthurerstrasse 190, CH-8057 Z¸rich
The reaction of aryl isoselenocyanates 8 with methyl 3-amino-4-chloro-1-ethylpyrrolo[3,2-c]quinoline-2-
carboxylate (6) in boiling pyridine leads to tetracyclic selenaheterocycles of type 9 in high yield (Scheme 3). A
reaction mechanism via an intermediate selenoureido derivative A and cyclization via nucleophilic substitution
of Cl by Se is proposed (Schemes 3 and 5). The reaction of 6 with 4-bromophenyl isothiocyanate yields the
analogous thiaheterocycle 12 (Scheme 4). The molecular structures of 9c and 12 have been established by X-ray
crystallography.
1. Introduction. The current interest in the chemistry of Se-containing compounds
is well-documented (cf. [1 4] and refs. cit. in [5]). A series of recent papers deals with
biological activities and the pharmaceutical potential of Se compounds (e.g., [6 10]).
For example, some organo-selenium compounds are active as insecticides and
microbicides [11], as prooxidants [12], and antimycobacterial agents [13]. Recently,
Koketsu et al. published some novel syntheses of selenaheterocycles [13 15].
Within our own research project, we have used aroyl isoselenocyanates 1a and N-
phenylbenzimidoyl isoselenocyanates 1b as conveniently accessible, cheap, and safe Se
reagents for the preparation of 1,2,3-selenadiazoles 2 [16] and 1,3-selenazole derivatives
3 [17], respectively (Scheme 1). In the case of 1c, treatment with amines led to 6H-
[5,1,3]benzoselenadiazocines 4 [18], whereas the base-catalyzed cyclization of 1d
yielded bis(2,4-diarylimidazol-5-yl) diselenides 5 [5].
Although the chemistry of Se-containing compounds is often similar to that of the
corresponding S analogues, some significant differences are also known, and because of
the toxicity and instability of many Se compounds, the synthesis of Se heterocycles is
much less developed. Therefore, new approaches by using more stable, less toxic, and
easily accessible Se reagents are of high interest. For this reason, we have investigated
reactions of aryl isoselenocyanates as starting materials for the preparation of
selenaheterocycles.
In the present paper, we report the results of the reaction of aryl isoselenocyanates
with methyl 3-amino-4-chloro-1-ethylpyrrolo[3,2-c]quinoline-2-carboxylate (6). The
latter was used recently by Mekheimer to prepare fused tri- and tetracyclic quinoline
derivatives [19]. Among several transformations, he described the reaction with phenyl
and allyl isothiocyanate, which gave
according to his interpretation
the
corresponding 5-substituted methyl 1-ethyl-4-thioxo-3(4H)-1,3,5,6-tetraazaaceanthryl-
ene-2-carboxylate 7 (Scheme 2).
1
)
Part of the planned Ph.D. thesis of P. K. A., Universit‰t Z¸rich.

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Helvetica Chimica Acta Vol. 86 (2003)
Scheme 1
Scheme 2
2. Results and Discussion. To a solution of 6 in anhydrous pyridine, ca. 1.1 equiv.
of the freshly prepared aryl isoselenocyanate 8 was added, and the mixture was heated
under reflux for 5 h. After evaporation of the solvent, trituration of the residue with
MeOH, and recrystallization, the corresponding yellowish crystalline product 9 was
obtained (Scheme 3). According to the CI-MS and elemental analyses, these products
were formed by addition of 6 and 8, and elimination of HCl. The IR spectra (KBr)
showed absorptions at 3274 3244 and 1714 1692 cmÀ1 for NH and the ester CˆO
group, and the corresponding signals appeared at 10.40 10.06 and 162.8 161.4 ppm in
1
the H- and 13C-NMR spectra. Other characteristic signals were present for the EtN

Helvetica Chimica Acta Vol. 86 (2003)
3237
Scheme 3
and the MeO groups as well as for the C-atoms of the polycyclic skeleton in the
aromatic region.
As we expected that the formed products were Se analogues of 7 (Scheme 2), we
tried to form the corresponding diselenides by oxidation (cf. [5]), but all attempts
failed. Furthermore, methylation of 9b by treatment with NaH and MeI gave product
10, which was not a methylseleno derivative. The Me absorption at 3.63 ppm
(1H-NMR) clearly shows that 10 is an N-Me derivative.
In the case of the 4-bromophenyl derivative 9c, single crystals were obtained from
DMF, and the 1H-5-selena-1,3,6-triazaaceanthrylene structure of the molecule was
established by X-ray crystallography (Fig. 1).
The tetracyclic ring system of 9c is almost planar, and the ester group is coplanar
with the ring system. The 4-bromophenyl ring at N(2) is twisted out of the heterocyclic
plane by ca. 238 (torsion angles C(2)ÀN(2)ÀC(17)ÀC(18) À158.5(3)8,
C(2)ÀN(2)ÀC(17)ÀC(22) 23.9(4)8). The Et group at N(6) is almost orthogonal to
the ring skeleton (C(5)ÀN(6)ÀC(25)ÀC(26) À96.5(3)8). The NH group forms an
intermolecular H-bond with the O-atom of the ester CˆO group of a neighboring
molecule, thereby linking the molecules into infinite chains, which run in the [101]
direction and have a graph set motif [21] of C(8).

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Helvetica Chimica Acta Vol. 86 (2003)
Fig. 1. ORTEP Plot [20] of the molecular structure of 9c (arbitrary numbering of atoms; 50% probability
ellipsoids)
A reaction mechanism for the formation of 9 is proposed in Scheme 3. Nucleophilic
addition of the NH2 group of 6 to the isoselenocyanate 8 leads to the selenoureido
derivative A. The new selenaheterocycle is formed by nucleophilic substitution of Cl of
the 2-chloroquinoline residue via attack of the Se-atom, where B is an intermediate. As
the reaction is carried out in pyridine, a base catalysis of the ring closure is likely.
Because of the discrepancy between the reported reaction of 6 with isothiocyanates
(Scheme 2) and the reaction with isoselenocyanates (Scheme 3), we also carried out a
reaction with an aryl isothiocyanate. Treatment of 6 with 4-bromophenyl isothiocya-
nate in pyridine at room temperature gave 12 in 64% yield (Scheme 4). According to
the 1H- and 13C-NMR spectra in (D7)DMF, there are two tautomeric forms 12 and 12'
present in a ratio of ca. 2 :1. Crystals suitable for X-ray crystallography were obtained
from DMSO (Fig. 2). The molecular structure of 12 is very similar to that of the
corresponding Se analogue 9c. The main difference is that the 4-bromophenyl ring at
N(2) is almost coplanar with the heterocyclic ring system (torsion angles
C(2)ÀN(2)ÀC(17)ÀC(18) À177.0(2)8, C(2)ÀN(2)ÀC(17)ÀC(22) 2.8(3)8). The
asymmetric unit contains one molecule of 12 plus one molecule of DMSO. The NH
group forms an intermolecular H-bond with the O-atom of a neighboring DMSO
molecule. This interaction does not form an extended network and has a graph set motif
of D.
Scheme 4

Helvetica Chimica Acta Vol. 86 (2003)
3239
Fig. 2. ORTEP Plot [20] of the molecular structure of 12 (arbitrary numbering of atoms; 50% probability
ellipsoids)
In conclusion, we have shown that the reactions of 6 with aryl isoselenocyanates
and isothiocyanates proceed in a consistent manner, leading to the fused tetracyclic ring
systems 9 and 12, respectively. In both cases, the ring closure of the intermediate ureido
derivative of type A takes place by the nucleophilic attack of the Se- and S-atom
(Scheme 5). The alternative cyclization via the N-atom of the ureido derivatives, which
was postulated to lead to the heterocycles of type 7 [19], was not observed. Therefore,
the structures proposed in [19] have to be revised.
Scheme 5
We thank the analytical units of our institute for spectra and analyses. Financial support of this work by the
Swiss National Science Foundation and F. Hoffmann-La Roche AG, Basel, is gratefully acknowledged.

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Helvetica Chimica Acta Vol. 86 (2003)
Experimental Part
1. General. See [16]. The aryl isoselenocyanates 8a 8d were prepared according to the protocol described
in [22]. To a stirred soln. of the corresponding N-arylformamide (40 mmol) in abs. toluene (100 ml) in an ice
bath were added Et3N (16.2 g, 160 mmol) and Se black powder. Then, phosgene (30 g of a 20% soln. in toluene,
60 mmol) was added slowly within 30 min. An exothermic reaction took place. After complete addition, the
suspension was heated under reflux for 8 10 h (TLC control). The mixture was filtered and washed with several
portions of toluene, the filtrate was concentrated and fractionated by column chromatography (SiO2 ; hexane).
Phenyl isoselenocyanate (8a) [22]: 4.84 g (40 mmol) of N-phenylformamide. Yield: 3.24 g (45%). 4-
Chlorophenyl isoselenocyanate (8b) [22]: 6.22 g (40 mmol) of N-(4-chlorophenyl)formamide. Yield: 4.77 g
(55%). 4-Bromophenyl isoselenocyanate (8c): 8.00 g (40 mmol) of N-(4-bromophenyl)formamide. Yield: 6.05 g
(58%). 4-Methoxyphenyl isoselenocyanate (8d) [22]: 6.05 g (40 mmol) of N-(4-methoxyphenyl)formamide.
Yield: 3.56 g (42%). N-(4-Chlorophenyl)- and N-(4-bromophenyl)formamide were prepared according to [23]
by heating the corresponding aniline (20 mmol) in 95% HCOOH under reflux for 30 min. After workup, the
products were recrystallized from H2O. N-(4-Methoxyphenyl)formamide was prepared according to [24]. After
evaporation of the solvent, the residue was dissolved in AcOEt, and the soln. was washed with 5% aq. NaHCO3
and H2O. The org. layer was dried (MgSO4), the solvent was evaporated, and the crude product was used
without further purification. Methyl 3-amino-4-chloro-1-ethylpyrrolo[3,2-c]quinoline-2-carboxylate (6) was
synthesized according to the protocol in [19]. Cream-colored crystals. M.p. 185 1868 (acetone). IR: 3496m,
3384m, 3068w, 3016w, 2985w, 2956m, 2930w, 1692s, 1602s, 1573s, 1556m, 1534s, 1507s, 1472m, 1435s, 1409w, 1374s,
1356m, 1330m, 1298m, 1276s, 1255m, 1240s, 1180s, 1160s, 1102s. 1H-NMR (500 MHz, (D6)DMSO): 8.38 (dd, J ˆ
8.4, 0.9, 1 arom. H); 7.93 (dd, J ˆ 8.2, 1.3, 1 arom. H); 7.73 (td, J ˆ 8.2, 1.3, 1 arom. H); 7.67 (td, J ˆ 8.4, 1.4, 1 arom.
H); 6.04 (s, NH2); 4.84 (q, J ˆ 7.0, CH2); 3.90 (s, MeO); 1.47 (t, J ˆ 7.0, MeCH2). 13C-NMR ((D6)DMSO): 161.7
(s, CO); 145.1, 144.3, 137.4, 136.4, 116.9, 108.0, 106.8 (7s, 7 arom. C); 129.0, 128.8, 126.7, 122.6 (4d, 4 arom. CH);
‡
51.1 (q, MeO); 42.0 (t, CH2); 15.2 (q, MeCH2). CI-MS: 304 (100, [M ‡ 1] ). Anal. calc. for C15H14ClN3O2
(303.74): C 59.31, H 4.65, N 13.83; found C 59.15, H 4.63, N 13.84.
2. Preparation of 1H-5-Selena-1,3,6-triazaaceanthrylene-2-carboxylates 9a 9d. General Procedure. To a
soln. of 6 in anh. pyridine, the freshly prepared aryl isoselenocyanate 8 was added under stirring at r.t. The
mixture was heated under reflux for 5 h. After cooling, the solvent was evaporated i.v., and the remaining oily
residue was triturated with MeOH. The resulting solid product was collected by filtration and purified by
recrystallization from MeOH or CH2Cl2/hexane.
Methyl 1-Ethyl-4-(phenylamino)-1H-5-selena-1,3,6-triazaaceanthrylene-2-carboxylate (9a). From 0.5 g
(1.64 mmol) of 6 and 0.33 g (1.81 mmol) of 8a. Yield: 0.55 g (75.3%). Yellowish crystals. M.p. 256.1 257.08
(MeOH). IR: 3244w, 3191w, 3125w, 3047m, 3012m, 2974m, 2931m, 1714s, 1628s, 1590s, 1569s, 1557s, 1546s,
1496s, 1456m, 1438s, 1371m, 1354m, 1312m, 1295m, 1269m, 1244m, 1216m, 1199m, 1183m, 1163m, 1140w, 1111s.
1H-NMR (500 MHz, (D6)DMSO): 10.20 (s, NH); 8.33 (d, J ˆ 7.6, 1 arom. H); 8.09 (d, J ˆ 8.0, 2 arom. H); 7.91
(dd, J ˆ 8.2, 1.2, 1 arom. H); 7.68 (td, J ˆ 8.1, 1.1, 1 arom. H); 7.61 (td, J ˆ 8.3, 1.3, 1 arom. H); 7.39 (dd, J ˆ 8.4, 7.4,
2 arom. H); 7.08( t, J ˆ 7.3, 1 arom. H); 4.95 (q, J ˆ 7.0, CH2); 3.99 (s, MeO); 1.51 (t, J ˆ 7.0, MeCH2). 13C-NMR
((D6)DMSO): 161.4 (s, CO); 152.4, 147.6, 147.2, 140.4, 135.4, 131.1 (6s, 7 arom. C); 128.7, 128.6, 128.5, 125.9,
122.9, 122.5, 119.4 (7d, 9 arom. CH); 117.9, 105.0 (2s, 2 arom. C); 51.5 (q, MeO); 41.9 (t, CH2); 15.4 (q, MeCH2).
‡
CI-MS: 451 (100, [M ‡ 1] ). Anal. calc. for C22H18N4O2Se (449.36)2): C 58.80, H 4.04, N 12.47; found: C 56.84, H
4.25, N 11.95.
Methyl 4-[(4-Chlorophenyl)amino]-1-ethyl-1H-5-selena-1,3,6-triazaaceanthrylene-2-carboxylate (9b).
From 0.4 g (1.31 mmol) of 6 and 0.31 g (1.42 mmol) of 8b. Yield: 0.55 g (87.3%). Yellowish crystals. M.p.
271.0 272.18 (MeOH). IR: 3261w, 3190w, 3102m, 3055m, 2990m, 2950m, 1694s, 1605s, 1570s, 1549s, 1489s,
1461m, 1435s, 1420w, 1400m, 1373s, 1353m, 1308s, 1292s, 1263m, 1246m, 1223s, 1196m, 1180m, 1161m, 1135w,
1110s, 1094m. 1H-NMR ((D7)DMF): 10.62 (s, NH); 8 .62 (d, J ˆ 8.2, 1 arom. H); 8.50 (d, J ˆ 8.8, 2 arom. H); 8.18
(d, J ˆ 8.0, 1 arom. H); 7.95 7.82 (m, 2 arom. H); 7.71 (d, J ˆ 8.8, 2 arom. H); 5.26 (q, J ˆ 7.0, CH2); 4.35 (s,
MeO); 1.85 (t, J ˆ 7.0, MeCH2). 13C-NMR ((D7)DMF): 162.8( s, CO)3); 153.0, 148.5, 140.5, 132.0, 129.8, 129.3,
118.1 (7s, 10 arom. C); 129.1, 127.5, 126.5, 123.4, 121.5, 119.0 (6d, 8arom. CH); 52.2 ( q, MeO); 42.9 (t, CH2); 15.9
‡
(q, MeCH2). CI-MS: 485 (100, [M ‡ 1] ). Anal. calc. for C22H17ClN4O2Se (483.81): C 54.62, H 3.54, N 11.58;
found: C 53.88, H 3.65, N 11.41.
2
)
)
In all Se-containing products, the values for C were too low.
Signal overlaps with the signal of DMF.
3

Helvetica Chimica Acta Vol. 86 (2003)
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Methyl 4-[(4-Bromophenyl)amino]-1-ethyl-1H-5-selena-1,3,6-triazaaceanthrylene-2-carboxylate (9c). From
0.6 g (1.97 mmol) of 6 and 0.56 g (2.14 mmol) of 8c. Yield: 0.9 g (86.5%). Colorless crystals. M.p. 265 2678
(MeOH), 266.8 267.0 8 (CH2Cl2/hexane). IR: 3274m, 3186m, 3099m, 3050m, 2989m, 1694s, 1606s, 1586s, 1570s,
1546s, 1487s, 1461m, 1435m, 1395m, 1374m, 1354w, 1309s, 1294s, 1264m, 1246m, 1223s, 1197m, 1181m, 1160m,
1135w, 1111m. 1H-NMR ((D7)DMF): 10.40 (s, NH); 8.40 (d, J ˆ 8.1, 1 arom. H); 8.21 (d, J ˆ 8.5, 2 arom. H); 7.94
(d, J ˆ 8.1, 1 arom. H); 7.69 (t-like, 2 arom. H); 7.61 (d-like, 2 arom. H); 5.03 (q, J ˆ 7.0, CH2); 4.11 (s, MeO); 1.60
(t, J ˆ 7.0, MeCH2). 13C-NMR ((D7)DMF): 162.7 (s, CO)3); 153.1, 148.6, 148.5, 140.9, 136.0, 131.2, 119.0, 117.6,
115.2, 105.8(10 s, 10 arom. C); 132.3, 129.9, 129.1, 126.5, 123.4, 121.9 (6d, 8arom. CH); 52.2 ( q, MeO); 42.9 (t,
‡
CH2); 15.9 (q, MeCH2). CI-MS: 529 (100, [M ‡ 1] ). Anal. calc. for C22H17BrN4O2Se (528.26): C 50.02, H 3.24,
N 10.61; found C 49.33, H 3.43, N 10.50.
Methyl 1-Ethyl-4-[(4-methoxyphenyl)amino]-1H-5-selena-1,3,6-triazaaceanthrylene-2-carboxylate (9d).
From 0.4 g (1.31 mmol) of 6 and 0.36 g (1.69 mmol) of 8d. Yield: 0.5 g (79.4%). Yellowish crystals. M.p.
249.2 250.08 (CH2Cl2/hexane). IR: 3262w, 3198w, 3123w, 3062m, 2988m, 2949m, 2833w, 1692s, 1601s, 1569s,
1535m, 1508s, 1476m, 1460m, 1438m, 1414m, 1372m, 1354m, 1297m, 1279w, 1241s, 1218s, 1197m, 1179w, 1161m,
1136w, 1110m. 1H-NMR (500 MHz, (D6)DMSO): 10.06 (s, NH); 8.30 (br. d, J ˆ 8.0, 1 arom. H); 8.00 (br. d, J ˆ
8.8, 2 arom. H); 7.89 (dd, J ˆ 8.2, 1.2, 1 arom. H); 7.66 (td, J ˆ 8.2, 1.2, 1 arom. H); 7.58 (td, J ˆ 8.2, 1.2, 1 arom.
H); 6.94 (d-like, J ˆ 9.1, 2 arom. H); 4.93 (q, J ˆ 7.0, CH2); 3.97, 3.77 (2s, 2 MeO); 1.50 (t, J ˆ 7.0, MeCH2).
13C-NMR ((D6)DMSO): 161.3 (s, CO); 154.9, 152.4, 147.1, 135.6, 133.7, 131.0, 128.4, 115.9, 104.6 (9s, 10 arom. C);
128.5, 125.8, 122.5, 120.5, 117.7, 113.7 (6d, 8arom. CH); 55.2, 51.6 (2 q, 2 MeO); 41.8( t, CH2); 15.3 (q, MeCH2).
‡
CI-MS: 481 (100, [M ‡ 1] ). Anal. calc. for C23H20N4O3Se (479.39): C 57.62, H 4.21, N 11.69; found C 55.90, H
4.22, N 11.32.
Methyl 4-[(4-Chlorophenyl)(methyl)amino]-1-ethyl-1H-5-selena-1,3,6-triazaaceanthrylene-2-carboxylate
(10). To a soln. of 9b (0.2 g, 0.4 mmol) in dry pyridine (30 ml) was added a suspension of NaH in mineral oil
(ca. 1.5 equiv.) and 1.2 equiv. MeI. Usual workup and crystallization yielded 0.1 g (50%) of 10. Creamy-colored
crystals. M.p. 215.1 215.58 (CH2Cl2/hexane). IR: 3181w, 3048w, 2927m, 1695s, 1611m, 1596s, 1584s, 1567s, 1552s,
1489s, 1461s, 1435s, 1405m, 1373s, 1350m, 1314s, 1285s, 1263m, 1243m, 1222s, 1191s, 1158m, 1127m, 1110s, 1090m.
1H-NMR ((D7)DMF): 8.37 (d, J ˆ 8.3, 1 arom. H); 8.35 (d-like, 1 arom. H); 7.88 (d-like, 2 arom. H); 7.85 7.49
(m, 4 arom. H); 5.00 (q, J ˆ 6.8, CH2); 3.97 (s, MeO); 3.63 (s, MeN); 1.57 (t, J ˆ 7.0, MeCH2). CI-MS: 499 (100,
‡
[M ‡ 1] ).
3. Preparation of Methyl 4-[(4-Bromophenyl)amino]-1-ethyl-1H-5-thia-1,3,6-triazaaceanthrylene-4-carbox-
ylate (12). In analogy to the General Procedure (Sect. 2), 12 was prepared from 0.4 g (1.32 mmol) of 6 and 0.29 g
(1.35 mmol) of 4-bromophenyl isothiocyanate. Yield: 0.4 g (63.5%). Pale-yellow crystals. M.p. 286.1 286.58
(MeOH). IR: 3416w, 3305s, 3194m, 3120m, 3054w, 2946w, 2926w, 2852w, 1662s, 1601s, 1562s, 1540s, 1487s, 1468s,
1439m, 1395m, 1378m, 1353w, 1308s, 1293m, 1261m, 1249w, 1223s, 1199m, 1179m, 1157m, 1132m, 1116m.
1H-NMR ((D7)DMF)4): 12.93 (s, 0.33 NH); 10.43 (s, 0.66 NH); 8.61 8.59 (d-like, 0.33 arom. H); 8.39 8.37 (d-
like, 0.66 arom. H); 8.24 8.22 (m, 2 arom. H); 7.93 7.92 (d-like, 0.33 arom. H); 7.89 7.88 (d-like, 0.66 arom.
H); 7.70 7.53 (m, 4 arom. H); 5.04 (q, J ˆ 7, CH2); 4.09, 4.04 (2s, MeO); 1.59 (t, J ˆ 7, MeCH2). 13C-NMR
((D7)DMF)4): 162.4, 162.0 (2s, CO); 153.0, 151.6, 151.1, 148.5, 148.0, 140.8, 135.1, 132.8, 132.6, 119.2, 119.1, 116.1,
115.3, 107.1, 10.2 (15s, 10 arom. C); 132.3, 132.2, 129.9, 129.4, 129.2, 126.5, 126.2, 123.6, 123.4, 122.3, 122.2 (11d, 8
‡
arom. CH); 52.0, 51.9 (2q, MeO); 42.8( t, CH2); 15.9 (q, MeCH2). CI-MS: 483 (100, [M ‡ 1] ). Anal. calc. for
C22H17BrN4O2S (481.36): C 54.89, H 3.56, N 11.64; found: C 54.06, H 3.68, N 11.54.
4. X-Ray Crystal-Structure Determination of 9c and 12 (Table, and Figs. 1 and 2)5). All measurements were
performed on a Nonius KappaCCD diffractometer [25] with graphite-monochromated MoKa radiation (l
0.71073 ä) 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 Figs. 1 and 2. Data reductions were performed
with HKL Denzo and Scalepack [26]. The intensities were corrected for Lorentz and polarization effects, and, in
the case of 9c, a numerical absorption correction [27] was applied, whereas, in the case of 12, an absorption
correction based on the multi-scan method [28] was applied. The structures were solved by direct methods using
SIR92 [29], which revealed the positions of all non-H-atoms. In the case of 12, the asymmetric unit contains one
4
)
)
Two tautomeric forms of 12 are present in a ratio of ca. 1:2. Some of the signals overlap.
CCDC-211324 and 211325 contain the supplementary crystallographic data for this paper. These data can
be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB21EZ, UK (fax: ‡44-(0)1223 336033;
e-mail: deposit@ccdc.cam.ac.uk)).
5

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Helvetica Chimica Acta Vol. 86 (2003)
Table. Crystallographic Data of Compounds 9c and 12
9c
12
Crystallized from
Empirical formula
Formula weight
Crystal color, habit
Crystal dimensions [mm]
Temperature [K]
Crystal system
Space group
DMF
C22H17BrN4O2Se
528.21
colorless, plate
0.05 Â 0.20 Â 0.23
160(1)
monoclinic
P21/n
DMSO
C22H17BrN4O2S ¥ C2H6OS
559.49
pale yellow, plate
0.05 Â 0.15 Â 0.22
160(1)
monoclinic
P21/n
Z
4
4
Reflections for cell determination
2q Range for cell determination [8]
67221
55
41355
4 60
4
Unit cell parameters a [ä]
13.0270(3)
9.4013(3)
17.5241(5)
110.975(1)
2004.0(1)
1.751
11.5740(1)
9.1938(1)
22.3318(3)
92.7150(5)
2373.64(5)
1.565
b [ä]
c [ä]
b [8]
V [ä3]
Dx [g cmÀ3
m(MoKa) [mmÀ1
]
]
3.901
1.948
Transmission factors [min; max]
Scan type
2q(max) [8]
0.463; 0.852
f and w
55
0.728; 0.930
f and w
60
Total reflections measured
Symmetry-independent reflections
Reflections with I > 2s(I)
Reflections used in refinement
Parameters refined
42812
4560
3347
4560
58214
6912
4925
6912
278316
Final R(F) [I > 2s (I) reflections]
0.0369
0.0851
0.0340; 1.4557
1.0581.038
0.0021(3)
0.001
0.0382
0.0960
0.0434; 0.5372
wR(F2) (all data)
Weighting parameters [a; b]a)
Goodness-of-fit
Secondary extinction coefficient
Final Dmax/s
0.0037(6)
0.005
0.50; À0.41
D1 (max; min) [e äÀ3
]
0.66; À0.56
a) wÀ1 ˆ s 2(Fo2) ‡ (aP)2 ‡ bP where P ˆ (Fo2 ‡ 2Fc2)/3.
molecule of 12 plus one molecule of DMSO. The non-H-atoms were refined anisotropically. In both structures,
the NH-atom was placed in the position indicated by a difference-electron-density map, and its position was
allowed to refine together with an isotropic displacement parameter. All remaining H-atoms were placed in
geometrically calculated positions and refined by using a riding model where each H-atom was assigned a fixed
isotropic displacement parameter with a value equal to 1.2Ueq of its parent C-atom (1.5Ueq for the Me groups).
Refinements of the structures were carried out on F2 using full-matrix least-squares procedures, which
minimized the function Sw(Fo2 À Fc2)2. A correction for secondary extinction was applied in both cases. Neutral
atom scattering factors for non-H-atoms were taken from [30a], and the scattering factors for H-atoms were
taken from [31]. Anomalous dispersion effects were included in Fc [32]; the values for f ' and f '' were those of
[30b]. The values of the mass attenuation coefficients are those of [30c]. All calculations were performed using
the SHELXL97 program [33].

Helvetica Chimica Acta Vol. 86 (2003)
3243
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Received May 28, 2003