Synthesis of 4-(phenylamino)quinazoline-2(1H)-selones and diselenides from isoselenocyanates: Dimroth rearrangement of an intermediate

Article abstract of DOI:10.1002/hlca.200490166

The reaction of anthranilonitriles 8 with phenyl isoselenocyanates (1a) in dry pyridine under reflux gave 4-(phenylamino)quinazoline-2(1H)-selones 9 (Scheme 2). They are easily oxidized and converted to diselenides of type 11. The analogous reaction of 8a

Full text of DOI:10.1002/hlca.200490166

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Synthesis of 4-(Phenylamino)quinazoline-2(1H)-selones and Diselenides
from Isoselenocyanates:
Dimroth Rearrangement of an Intermediate
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 anthranilonitriles 8 with phenyl isoselenocyanates (1a) in dry pyridine under reflux gave 4-
(phenylamino)quinazoline-2(1H)-selones 9 (Scheme 2). They are easily oxidized and converted to diselenides
of type 11. The analogous reaction of 8a with phenyl isothiocyanate (1b) yielded the quinazoline-2(1H)-thione
10 (Scheme 2). A reaction mechanism via a Dimroth rearrangement of the primarily formed intermediate is
presented in Scheme 3. The molecular structures of 10 and 11a have been established by X-ray crystallography.
Unexpectedly, no selone or diselenide was obtained in the case of the reaction with 3-aminobenzo[b]furan-2-
carbonitrile (14). The only product isolated was the selenide 16 (Scheme 4), the structure of which has been
established by X-ray crystallography.
1. Introduction. In recent years, the interest in the chemistry of Se-containing
compounds has increased remarkably due to their chemical properties [1 4] and
biological activities [5 7] (see also refs. cit. in [8 12]). Selenium, for a long time
recognized as dietary antioxidant [13], is now known to be an essential component of
the active sites of several enzymes, including glutathione peroxidase [14] and
thioredoxin reductase [15], which catalyze reactions essential for the protection of
cellular components against oxidative and free radical damage. This is a good basis for
the development of novel pharmaceutical agents that contain selenium or that target
specific aspects of selenium metabolism. Among them are orally active antihyperten-
sive, anticancer, antiviral, and immunosupressive organoselenium compounds, as well
as those that reduce oxidative tissue damage and endema [16]. Hatfield [17] discussed a
large body of evidence that indicates that selenium is a cancer-chemopreventive agent.
Further evidence points to its role in preventing heart disease, and other cardiovascular
and muscle disorders, and in delaying the progression of AIDS in HIV-infected
patients.
For these reasons, the design and synthesis of organoselenium compounds,
especially Se-containing heterocycles, are of current interest [18 26]. It has been
shown that isoselenocyanates are versatile Se reagents for the preparation of
selenaheterocycles, e.g., benzo[b]selenophenes [27], 1,2,3-selenadiazoles [28][29],
selenapentalenes [30], 1,3-diselenol-2-imines [31], and 1,3-selenazoles [32]. In some
other cases, heteropolycyclic selones were the products [33][34]. Recently, we have
shown that aryl isoselenocyanates 1 are convenient precursors for the introduction of
Se into four- (2) [11], five- (3) [10], and six-membered selenaheterocycles (4) [9]
1
)
Part of the Ph.D. Thesis of P. K. A., Universit‰t Z¸rich, 2004.

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(Scheme 1). Furthermore, N-arylbenzimidoyl isoselenocyanates 5a on treatment with
primary or secondary amines gave 6H-[5,1,3]benzoselenadiazocines 6 [12], whereas N-
(4-nitrobenzyl)benzimidoyl isoselenocyanates 5b underwent a base-catalyzed cycliza-
tion and an oxidative dimerization to yield di(imidazol-5-yl) diselenides 7 [8] (Scheme 1).
Scheme 1
In the present paper, we report on the reaction of phenyl isoselenocyanate (1a) with
anthranilonitriles (2-aminobenzonitriles). The analogous reaction of anthranilonitrile
with phenyl isothiocyanate to give 1,2-dihydro-4-(phenylamino)quinazoline-2-thione
has already been reported by Taylor and Ravindranathan [35] and by Pazdera et al.
[36].
2. Results and Discussion. To a solution of the corresponding 2-aminobenzonitrile
8 in anhydrous pyridine, ca. 1 equiv. of freshly prepared phenyl isoselenocyanate (1a)
was added, and the mixture was heated to reflux for 2.5 h. After evaporation of the
solvent, the residue was triturated with MeOH, and a yellowish crystalline product was
obtained in the cases of 9a 9c (Scheme 2). The analogous reaction of 8a with phenyl
isothiocyanate (1b) led to the corresponding thione 10, which has been described
previously [35]. The structures of 9 and 10, i.e., 4-(phenylamino)quinazoline-2(1H)-

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Scheme 2
selones and 4-(phenylamino)quinazoline-2(1H)-thione, respectively, were confirmed
by their NMR, MS, and IR data, and elemental analyses. In the case of 10, the structure
was established by X-ray crystallography (Fig. 1).
The asymmetric unit contains one molecule of 10 and one MeOH molecule. The
entire molecule of 10 is almost completely planar, with the largest deviation from the
least-squares plane being 0.062(2) ä for C(14). The N(1)H group in the six-membered
ring forms an intermolecular H-bond with the S-atom of an adjacent molecule 10. This
interaction links pairs of 10 into centrosymmetric dimers, which have a graph set motif
[38] of R22(8). The exocyclic N(4)H group forms an intermolecular H-bond with the O-
atom of MeOH, which, in turn, forms a H-bond with the S-atom of a different molecule
of 10. These interactions link the moieties into centrosymmetric tetramers composed of
two molecules 10 and two MeOH molecules. The tetramers have a graph set motif of
R44(16). The combination of all H-bonding interactions results in extended chains,
which run parallel to the [101] direction, where the links in the chain are alternately the
dimeric and the tetrameric units.
All attempts to obtain single crystals of the selone 9a failed. During recrystallization
from MeCN, oxidative dimerization to give diselenide 11a occurred in almost
quantitative yield (Scheme 2). It is worth mentioning that the formation of 11b from
9b took place more slowly; the conversion was realized in good yield by bubbling O2
through a solution of 9b in pyridine at room temperature. The S analogue 10 was even
more stable, and no disulfide was obtained after treatment with O2. Finally, the
oxidation was successful when a solution of 10 in pyridine was treated with I2 at room
temperature.

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Fig. 1. ORTEP Plot [37] of the molecular structure of 10 (arbitrary numbering of the atoms; 50% probability
ellipsoids)
The structure of 11a was again established by X-ray crystallography (Fig. 2). Single
crystals of 11a were obtained by crystallization from MeCN. In one of several attempts,
a single crystal of a minor product (< 5%) was also isolated. The structure of this
product was established as triselenide 13 (Fig. 2).
The asymmetric unit of 11a contains one diselenide molecule and two MeOH
molecules. The bond lengths within the pyrimidine ring, plus the exocyclic CÀN bond
indicate significant delocalization of the p-electrons in these regions of the molecule.
The coordination about N(4) and N(20) is trigonal planar rather than tetrahedral, and
the torsion angles N(3)ÀC(4)ÀN(4)ÀC(11) and N(19)ÀC(20)ÀN(20)ÀC(27) are
5.9(5) and 5.5(5)8, respectively. However, the Ph rings at N(4) and N(20) are twisted
significantly out of the plane of the heterocycle (the torsion angles
C(4)ÀN(4)ÀC(11)ÀC(12) and C(20)ÀN(20)ÀC(27)ÀC(32) are À 32.1(5) and
38.4(5)8, resp.). The two heterocyclic moieties of 11a are almost orthogonal to each
other, with the mean planes of the fused-ring systems intersecting at an angle of
81.88(9)8. This is the result of the torsion angle of the diselenide bond
C(2)ÀSe(1)ÀSe(2)ÀC(18) being À 91.4(1)8. Turns of ca. 908 about chalcogenic bonds
are quite common for both oligosulfides [39] and oligoselenides. A search of the
January 2004 issue of the Cambridge Structural Database [40] revealed reliable
structures (R < 0.075) for 80 neutral acyclic organic oligoselenides from which 92
independent structural fragments of the type XÀSeÀSeÀX (X ˆ any element,
including a further Se-atom) were obtained. The absolute value of the XÀSeÀSeÀX

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Fig. 2. ORTEP Plots [37] of the molecular structure of a) 11a and b) 13 (arbitrary numbering of the atoms; 50%
probability ellipsoids)

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torsion angle is clearly clustered around 908 with 70 of the 92 fragments lying in the
range 72 1058. Another eleven conformations have torsion angles close to 180. Each of
the two NH groups, N(4)H and N(20)H, of 11a forms an intermolecular H-bond with a
different symmetry-independent neighboring MeOH molecule. These MeOH mole-
cules, in turn, form intermolecular H-bonds with N(17) and N(1), respectively, of the
pyrimidine rings of other diselenide molecules. Considering the route through one of
the symmetry-independent MeOH molecules, the H-bonding interactions link 11a and
the MeOH molecule alternately into extended chains, which run parallel to the z-axis
and have a graph set motif of C(11). The route through the other MeOH molecule
forms identical chains, but these chains run parallel to the y-axis. The combination of all
H-bonding interactions links the molecules into an infinite two-dimensional network
that lies parallel to the yz-plane.
The molecules of 13 possess crystallographic C2 symmetry with the twofold axis
passing through the central Se-atom, and the asymmetric unit includes one H2O
molecule. Although 13 is achiral, the compound has crystallized in a non-centrosym-
metric polar space group, and the absolute structure has been determined confidently
by refinement of the absolute structure parameter. Similar to the disulfide 11a, the two
heterocyclic moieties of 13 are almost orthogonal to each other, with the mean planes
of the fused-ring systems intersecting at an angle of 74.34(7)8. As discussed above for
11a, the XÀSeÀSeÀX torsion angles (equal by symmetry) are again close to 908
(C(2)ÀSe(2)ÀSe(1)ÀSe(2') À 84.98(7)8). Each NH group of 13 forms an intermo-
lecular H-bond with the O-atom of an adjacent H2O molecule, so that one molecule of
13 interacts with two H2O molecules. In turn, the H2O molecule acts as a donor for two
intermolecular H-bonds, one involving the ring-bonded Se-atom of a second molecule
of 13, while the other involves one of the ring N-atoms from a third molecule of 13. The
NÀH ¥¥¥ OÀH ¥¥¥ N interactions, combined with the twofold symmetry of 13, link the
molecules into infinite two-dimensional networks. The NÀH ¥¥¥ OÀH ¥¥¥ Se interac-
tions cross-link these two dimensional networks to form a three-dimensional H-bonded
framework overall.
In analogy to the formation of 4-(phenylamino)quinazoline-2(1H)-thione (10)
[35][36], a reaction mechanism for the formation of the Se-analogues 9 is proposed in
Scheme 3. Addition of the NH2 group of 8 to 1a leads to the selenourea derivative A,
which undergoes a ring closure to give B (or its tautomer). The S analogues of A and B
have been described as products of the reaction of 8a and 1b at 508 (without solvent)
and in boiling benzene, respectively [35][36]2). An isomerization via ring opening to C
2
)
In these two references, divergent observations are reported. Some results described in [35], e.g., the
formation of the S-analogue of A, could not be reproduced [36].

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Scheme 3
and a new ring closure leads to D, which tautomerizes to give 9, similar to the Dimroth
rearrangement [41]. Whereas the analogous isomerization has been reported by Taylor
and Ravindranathan [35], it did not occur under similar conditions according to
Pazdera et al. [36]. The latter authors obtained the imino derivative of type B as a
stable compound. On the other hand, the reaction of 8a and 1b in refluxing pyridine,
carried out by us, led exclusively to 10, the structure of which has unequivocally been
established by X-ray crystallography.
Recently, Sangapure and Mulagi reported that the reaction of phenyl isothiocyanate
(1b) with 3-aminobenzo[b]furane-2-carbonitrile (14) [42] gave the benzofuro[3,2-d]-
pyrimidine derivative 15 [43] (Scheme 4). When we carried out the reaction of 14 with
phenyl isoselenocyanate (1a) in refluxing pyridine, we obtained only one product,
‡
which showed an [M ‡ 1] peak at m/z 601 (ESI-MS). The NMR spectra indicated a
symmetrical structure with two benzofuro[3,2-d]pyrimidine rings. Finally, an X-ray
crystal-structure determination established structure 16 (Fig. 3). In both halves of the
molecule, the pyrimidine ring bears a PhNH group. Therefore, a Dimroth rearrange-
ment of the initially formed product with an imino and an N-phenyl group had
occurred, similar to the reaction sequence depicted in Scheme 3. The most remarkable
feature of the structure is the presence of only one Se atom. Although we are not able
to offer a convincing reaction mechanism for the formation of 16, SeÀC Bond
formation according to F or G could be proposed. Another possibility is the

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Scheme 4
Fig. 3. ORTEP Plot [37] of the molecular structure of 16 (arbitrary numbering of the atoms, 50% probability
ellipsoids, only one conformation of the disordered Ph ring is shown)

Helvetica Chimica Acta Vol. 87 (2004)
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nucleophilic addition of F to the isoselenocyanate H, which is proposed as an
intermediate of the Dimroth rearrangement (see C in Scheme 3), to give I, and
subsequent cyclization and elimination of H2Se.
The asymmetric unit of 16 contains one molecule of 16 plus two DMF molecules.
The Ph group at N(23) is disordered over two approximately equally occupied
orientations, which differ by a rotation of the ring plane by ca. 258 about the ipso-NÀC
bond. The mean planes of the fused-ring systems of 16 intersect at an angle of
55.79(5)8. Each NH group forms an intermolecular H-bond with the O-atom of an
adjacent DMF molecule.
Finally, phenyl isoselenocyanate (1a) has been reacted with 4-(dimethylamino)ani-
line (17a) and 4-methoxyaniline (17b) in toluene in the presence of Et3N. The reactions
at room temperature and at 508 gave the corresponding selenourea derivatives 18a and
18b, respectively, in good yields (Scheme 5). Whereas 18a is a new compound, 18b has
been prepared previously [44] from the corresponding urea derivative and H2Se, which
is extremely toxic and inconvenient.
Scheme 5
In conclusion, we have shown that the reactions of 8 with phenyl isoseleno- and
isothiocyanates (1a and 1b, resp.) proceed in an analogous manner leading to

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quinazoline derivatives of type 9 and 10, respectively. The selones of type 9 can be
converted smoothly to diselenides 11 by oxidation with O2. The analogous oxidation of
thione 10 required more-drastic conditions; it was carried out by treatment with I2. On
the other hand, the reaction of 14 with phenyl isoselenocyanate (1a) led to a completely
different product, i.e., the selenide 16, compared with the product obtained from the
reaction with phenyl isothiocyanate (1b). Finally, the preparation of selenoureas of
type 18 is more convenient than the method described in the literature.
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.
Experimental Part
1. General. See [29]. IR Spectra in KBr, absorptions in cmÀ1; NMR spectra in (D6)DMSO unless otherwise
stated, d in ppm; 13C-signal multiplicity from DEPT spectra; ESI-MS on a Finnigan TSQ-700 instrument.
2. Starting Materials. The phenyl isoselenocyanates 1a 1c were prepared according to the protocol
described in [45]. 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 over 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, then the filtrate was concentrated and chromatographed (SiO2; hexane).
Phenyl Isoselenocyanate (1a) [45]: from 4.84 g (40 mmol) of N-phenylformamide. Yield: 3.24 g (45%). 3-
Aminobenzofuran-2-carbonitrile (14) was prepared according to the protocol described in [42]. 1H-NMR
((D6)DMSO): 7.92 (d-like, 1 arom. H); 7.55 7.46 (m, 2 arom. H); 7.34 7.29 (t-like, 1 arom. H); 6.64 (s, NH2).
13C-NMR ((D6)DMSO): 154.1, 142.4, 120.9, 114.3, 106.4 (5s, 4 arom. C, CN); 129.1, 122.6, 121.2, 111.7
(4d, 4 arom. CH).
3. Synthesis of 4-(Phenylamino)quinazoline-2(1H)-selones 9. 3.1. 4-(Phenylamino)quinazoline-2(1H)-
selone (9a). Freshly prepared 1a (0.6 g, 3.30 mmol) was added to a stirred soln. of 2-aminobenzonitrile (8a;
0.39 g, 3.30 mmol) in dry pyridine at r.t., and the mixture was heated to reflux for 2.5 h. The solvent was removed
under reduced pressure, the remaining oil was dissolved in MeOH, and yellow-greenish crystals of 9a formed,
which were recrystallized from MeCN. Yield of 9a: 0.8g (81.6%). M.p. 225 240 8 (MeCN). IR: 2962m, 1606s,
1563s, 1521s, 1450s, 1426s, 1375s, 1352s, 1334s, 1279s, 1249s, 1183s, 1129m, 1080m. 1H-NMR ((D6)DMSO): 13.19,
10.13 (2s, 2 NH); 8.42 (d, J ˆ 8.1, 1 arom. H); 7.89 7.21 (m, 8arom. H). 1D-NOESY: Irradiation of H ÀC(8)
increased the intensity of the peak of HÀN(1), and irradiation of HÀC(5) increased the intensities of the signals
of NH and the ortho-H-atoms of the PhN group. 13C-NMR ((D6)DMSO): 177.5 (s, SeC); 153.1 (s, C(4)); 141.3,
137.9, 110.4 (3s, 3 arom. C); 134.5, 128.4, 124.9, 124.2, 123.8, 123.2, 115.8 (7d, 9 arom. CH). ESI-MS: 324 (100,
‡
[M ‡ Na] ). Anal. calc. for C14H11N3Se (300.22): C 56.01, H 3.69, N 14.00; found: C 55.80, H 3.84, N 14.22.
3.2. 7-Methyl-4-(phenylamino)quinazoline-2(1H)-selone (9b). The reaction was performed as described in
Sect. 3.1 with 2-amino-4-methylbenzonitrile (8b; 0.44 g, 3.30 mmol) and 1a (0.6 g, 3.30 mmol). Yield of 9b: 0.7 g
(49.3%). M.p. 217.0 219.08 (MeOH). Pale yellow crystals. IR: 3404w, 3075m, 3021m, 2957m, 2915m, 2860m,
1625s, 1604s, 1567s, 1536s, 1493s, 1448s, 1398m, 1370s, 1342s, 1282s, 1251m, 1226m, 1187s, 1146m, 1101w, 1079m.
1H-NMR ((D6)DMSO): 13.10, 10.04 (2s, 2 NH); 8.30 (d, J ˆ 8.3, 1 arom. H); 7.89 (d, J ˆ 7.9, 2 arom. H); 7.46
7.20 (m, 6 arom. H); 2.43 (s, Me). 13C-NMR ((D6)DMSO): 177.4 (s, SeC); 153.1 (s, C(4)); 145.3, 141.5, 138.1,
108.4 (4s, 4 arom. C); 128.4, 125.7, 124.8, 123.7, 123.1, 115.3 (6d, 8arom. CH); 21.5 ( q, Me). CI-MS: 316 (84,
‡
[M ‡ 1] ). Anal. calc. for C15H13N3Se (314.24): C 57.33, H 4.17, N 13.37; found: C 56.29, H 4.14, N 12.91.
3.3. 7-Chloro-4-(phenylamino)quinazoline-2(1H)-selone (9c). The reaction was performed as described in
Sect. 3.1 with 2-amino-4-chlorobenzonitrile (8c; 0.84 g, 5.50 mmol) and 1a (1.00 g (5.50 mmol). Yield of 9c: 0.7 g
(38.3%). M.p. 192.1 194.08 (MeOH). Brownish crystals. IR: 3065m, 3014m, 2899m, 1606s, 1557s, 1528s, 1484s,
1448s, 1393s, 1353s, 1306m, 1289m, 1273m, 1235m, 1180s, 1145m, 1095m, 1071m, 1030w. 1H-NMR ((D6)DMSO):
13.18, 10.22 (2s, 2 NH); 8.45 (d, J ˆ 8.8, 1 arom. H); 7.86 (d-like, 2 arom. H); 7.80 7.09 (m, 5 arom. H).
13C-NMR ((D6)DMSO): 178.5 (s, SeC); 152.6 (s, C(4)); 142.2, 139.1, 137.8, 109.4 (4s, 4 arom. C); 128.5, 126.2,
125.1, 124.3, 123.2, 115.0 (6d, 8arom. CH).
4. Synthesis of 4-(Phenylamino)quinazoline-2(1H)-thione (10). The reaction was performed as described in
Sect. 3.1 with 8a (0.87 g, 7.40 mmol) and 1b (1.00 g, 7.40 mmol). Yield of 10: 1.46 g (78.0%). M.p. 243.0 244.08

Helvetica Chimica Acta Vol. 87 (2004)
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(MeCN). Yellowish crystals. IR: 3035m, 1622s, 1607s, 1528s, 1493s, 1451s, 1425m, 1353s, 1335s, 1281m, 1188s,
1
1160m, 1132m, 1087m. H-NMR ((D6)DMSO): 12.72, 10.00 (2s, 2 NH); 8.41 (d, J ˆ 8.2, 1 arom. H); 7.90 7.19
(m, 8arom. H). 13C-NMR ((D6)DMSO): 180.2 (s, CS); 154.5 (s, C(4)); 141.2, 138.1, 110.0 (3s, 3 arom. C); 134.3,
‡
128.3, 124.7, 123.6, 123.4, 123.2, 115.5 (7d, 9 arom. CH). ESI-MS: 254 (100, [M ‡ 1] ). Anal. calc. for C14H11N3S
(253.32): C 66.38, H 4.38, N 16.59; found: C 66.03, H 4.36, N 17.25.
5. Synthesis of Bis[4-(phenylamino)quinazolin-2-yl] Diselenides 11. 5.1. Bis[4-(phenylamino)quinazolin-2-
yl] Diselenide (11a). A soln. of 9a (0.6 g, 2.0 mmol) in MeCN (15 20 ml) was concentrated a little and allowed
to stand at r.t. for several h. Pale-yellow crystals of 11a formed, and they were separated by filtration: 0.54 g
(90.0%) of 11a. M.p. 158.0 158.58. IR: 3624w, 3423w, 3374m, 3100w, 3055m, 1617s, 1602s, 1560s, 1518s, 1488s,
1447s, 1440s, 1400s, 1358m, 1339s, 1312m, 1299m, 1280s, 1246m, 1193s, 1153m, 1124m, 1112w, 1081m. 1H-NMR
((D6)DMSO): 9.85 (s, 2 NH); 8.52 (d, J ˆ 8.0, 1 arom. H); 7.94 6.90 (m, 16 arom. H). 13C-NMR ((D6)DMSO):
161.3, 157.1, 150.3, 138.5, 113.3 (5s, 10 arom. C); 133.6, 128.0, 126.5, 125.6, 123.5, 123.3, 121.8 (7d, 18arom. CH).
‡
ESI-MS: 601 (100, [M ‡ 1] ). Anal. calc. for C28H20N6Se2 (598.42): C 56.20, H 3.37, N 14.04; found: C 56.00, H
3.50, N 14.25.
Suitable crystals for an X-ray crystal-structure determination of 11a were obtained from MeOH. During
attempts to grow crystals of 9a, one crystal of the triselenide 13 with m.p. 114.1 115.28 was obtained from
MeCN.
5.2. Bis{4-[(4-methylphenyl)amino]quinazolin-2-yl} Diselenide (11b). O2 was bubbled through a soln. of 9b
(0.3 g, 95 mmol) in pyridine (10 15 ml) for 2 h. The solvent was removed i.v., and the remaining oil was treated
with MeOH to give pale-yellow crystals of 11b. Yield: 0.2 g (66.0%). M.p. 222.2 224.18 (MeOH). Pale-yellow
crystals. IR: 3628m, 3427m, 3320m, 3050w, 2914w, 1622s, 1601m, 1560s, 1514s, 1488s, 1447s, 1406s, 1341m, 1310m,
1296m, 1283s, 1251m, 1229m, 1203m, 1135w, 1081m. 1H-NMR ((D6)DMSO): 9.77 (s, 2 NH); 8.41 (d, J ˆ 8.5,
2 arom. H); 7.95 (d, J ˆ 7.7, 4 arom. H); 7.52 6.91 (m, 12 arom. H); 2.49 (s, 2 Me). 13C-NMR ((D6)DMSO):
161.2, 157.0, 150.5, 144.0, 138.7, 111.2 (6s, 12 arom. C); 128.0, 127.3, 125.8, 123.4, 123.0, 121.6 (6d, 16 arom. CH);
‡
21.2 (q, 2 Me). ESI-MS: 629 (100, [M ‡ 1] ).
6. Synthesis of Bis[4-(phenylamino)quinazolin-2-yl] Disulfide (12). To a soln. of 10 (1.0 g, 3.95 mmol) in
pyridine (20 25 ml) was added 0.55 equiv. of I2, and the mixture was stirred at r.t. for 1 h. The soln. was poured
into H2O, extracted with CH2Cl2, and the org. layer 1 was separated. The aq. layer was mixed with NaHCO3 and
extracted again with CH2Cl2, and the org. layer 2 was separated. The solvent of org. layer 1 was evaporated i.v.
The residue was treated with an aq. soln. of Na2S2O3 and extracted with CH2Cl2. This org. layer was combined
with layer 2, and the soln. was concentrated i.v. Pale-yellow crystals of 12 formed. Yield: 0.71 g (71.3%). M.p.
89.1 90.18 (CH2Cl2). IR: 3745w, 3422m, 3059w, 2924w, 1616s, 1601s, 1563s, 1520s, 1490s, 1448s, 1406s, 1364m,
1339m, 1307m, 1283s, 1249m, 1194m, 1127w, 1081m, 1031w. 1H-NMR ((D6)DMSO): 9.92 (s, 2 NH); 8.55 (d, J ˆ
8.2, 2 arom. H); 7.90 6.92 (m, 16 arom. H). 13C-NMR ((D6)DMSO): 164.5, 157.4, 150.3, 138.5, 113.3
(5s, 10 arom. C); 133.6, 128.0, 126.5, 125.4, 123.4, 123.2, 121.6 (7d, 18arom. CH). ESI-MS: 505 (100, [ M ‡
‡
1] ). Anal. calc. for C28H20N6S2 (504.63): C 66.64, H 3.99, N 16.65; found: C 65.77, H 4.06, N 16.53.
7. Synthesis of Bis[4-(phenylamino)benzofuro[3,2-d]pyrimidin-2-yl] Selenide (16). The reaction was
carried out as described in Sect. 3.1 with 3-amino[1]benzofuran-2-carbonitrile (14, 0.58g, 3.67 mmol) and 1a
(0.6 g, 3.30 mmol). Yield of 16: 0.3 g (27.3%). M.p. 158.0 158.28 (MeCN). Yellowish crystals. IR: 3408m,
3347m, 3056m, 2923w, 2852w, 2253w, 1634s, 1613s, 1581s, 1563s, 1514s, 1497s, 1461m, 1437s, 1382m, 1332m,
1299m, 1284s, 1267s, 1223m, 1200m, 1145m, 1133m, 1095m, 1079w, 1031w, 1010w. 1H-NMR ((D6)DMSO): 10.29
(s, 2 PhNH); 8.14 (d, J ˆ 7.8, 2 arom. H); 7.91 6.81 (m, 18arom. H). 13C-NMR ((D6)DMSO): 159.5, 156.0,
147.1, 146.3, 138.7, 133.9 (6s, 14 arom. C); 130.7, 128.0, 124.3, 122.9, 121.6, 120.2, 112.7 (7d, 18arom. CH). ESI-
‡
MS: 601 (100, [M ‡ 1] ). Anal. calc. for C32H20N6O2Se (599.50): C 64.11, H 3.36, N 14.02; found: C 62.95, H 3.62,
N 14.87.
Suitable crystals for the X-ray crystal-structure determination were grown from DMF.
8. Preparation of N,N'-Diarylselenoureas 18. 8 .1. N-[4-(Dimethylamino)phenyl]-N'-phenylselenourea (18a).
To a stirred soln. of 4-(dimethylamino)aniline (0.45 g, 3.30 mmol) in toluene (20 25 ml) at r.t. were added 1a
(0.6 g, 3.30 mmol) and 3 drops of Et3N. The mixture was stirred for 10 min at r.t. and 20 min at 508. The soln. was
concentrated i.v., and the product precipitated was isolated by filtration. Yield of 18a: 0.85 g (81.0%). M.p.
138.0 138.58 (toluene). Grey crystals. IR: 3567w, 3167s, 3000s, 2799m, 2037w, 1948w, 1897w, 1614m, 1599m,
1591m, 1578m, 1552s, 1494s, 1450m, 1323s, 1226s, 1188m, 1167m, 1131m. 1H-NMR (CDCl3): 8.70 7.80
(br. s, 2 NH); 7.35 6.64 (m, 7 arom. H); 6.62 (AA'BB', J ˆ 1.9, 2 arom. H); 2.90 (s, 2 Me). 13C-NMR (CDCl3)3):
3
)
Two singlets for arom. C are missing or overlap with other signals.

1884
Helvetica Chimica Acta Vol. 87 (2004)
179.0 (s, SeC); 150.0 (s, 1 arom. C); 129.1, 127.3, 127.0, 125.6, 112.7 (5d, 9 arom. CH); 40.3 (q, 2 Me). ESI-MS:
‡
320 (100, [M ‡ 1] ). Anal. calc. for C15H17N3Se (318.28): C 56.61, H 5.38, N 13.20; found: C 56.48, H 5.42, N
13.33.
8.2. N-(4-Methoxyphenyl)-N'-phenylselenourea (18b) [44]. In analogy to Sect. 8.1, 4-methoxyaniline (0.2 g,
1.65 mmol) and 1a (0.3 g, 1.65 mmol) were reacted at r.t. for 2 h. Yield of 18b: 0.3 g (60.0%). M.p. 176.0 176.58
(MeCN). Grey crystals. IR: 3457m, 3175s, 3035s, 3006s, 2838m, 2058w, 1957w, 1912w, 1610m, 1599m, 1589m,
1
1556s, 1527s, 1506s, 1467m, 1450m, 1417m, 1337s, 1296s, 1249s, 1220m, 1182m, 1169m, 1102m, 1034s. H-NMR
((D6)DMSO): 9.93 (br. s, 2 NH); 7.41 6.92 (m, 7 arom. H); 6.89 (AA'BB', J ˆ 7.2, 2 arom. H); 3.75 (s, Me).
13C-NMR ((D6)DMSO): 178.6 (s, SeC); 157.0, 139.6, 132.3 (3s, 3 arom. C); 128.3, 126.7, 125.0, 124.7, 113.7
‡
(5d, 9 arom. CH); 55.1 (q, Me). ESI-MS: 305 (100, [M ‡ 1] ). Anal. calc. for C14H14N2OSe (305.23): C 55.09, H
4.62, N 9.18; found: C 54.92, H 4.74, N 9.17.
9. X-Ray Crystal-Structure Determination of 10, 11a, 13, and 16 (see Table and Figs. 1 3)4). All
measurements were performed on a Nonius KappaCCD diffractometer [46] 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 3. Data reduction
was performed with HKL Denzo and Scalepack [47]. The intensities were corrected for Lorentz and
polarization effects, and absorption corrections were applied (multi-scan method [48] for 10 and a numerical
correction [49] for 11a, 13, and 16). Each structure was solved by direct methods with SHELXS97 [50] in the
cases of 10, 13, and 16, and SIR92 [51] in the case of 11a. The asymmetric unit in the structure of 10 contains one
molecule of the thione plus one MeOH molecule, while that of 11a contains one diselenide molecule plus two
MeOH molecules, and that of 13 contains one half of the triselenide molecule, which sits across a two-fold axis,
plus one H2O molecule. The asymmetric unit of 16 contains one molecule of the selenide plus two molecules of
DMF. In addition, the Ph group at N(23) of 16 is disordered over two orientations, which differ by a rotation of
the ring plane of ca. 258. Two positions were defined for each atom of this ring, and refinement of constrained
site occupation factors for the two orientations yielded a value of 0.51(2) for the major conformation. Bond-
length and similarity restraints were applied to all CÀC bonds within both orientations of the disordered ring,
and neighboring atoms within and between each conformation of the disordered ring were restrained to have
similar atomic displacement parameters.
The non-H-atoms in each structure were refined anisotropically. With the exception of the disordered H-
atoms at N(23) in 16, the amine H-atoms, as well as the OH H-atoms of any MeOH or H2O solvent molecules,
were placed in the positions indicated by difference-electron-density maps, and their positions were allowed to
refine together with individual isotropic displacement parameters. All remaining H-atoms in each structure
were placed in geometrically calculated positions, and each was assigned a fixed isotropic displacement
parameter with a value equal to 1.2 Ueq of its parent atom. Refinement of each structure was carried out on F (10,
11a, 13) or F2 (16) using full-matrix least-squares procedures, which minimized the function Sw(j Fo jÀj Fc j )2 or
Sw(Fo2 À Fc2)2, resp. A correction for secondary extinction was applied in the case of 11a. For 13, refinement of
the absolute structure parameter [52] yielded a value of À 0.010(9), which confidently confirms that the refined
model represents the true absolute structure. Neutral-atom-scattering factors for non-H-atoms were taken from
[53a], and the scattering factors for H-atoms were taken from [54]. Anomalous dispersion effects were included
in Fc [55]; the values for f ' and f '' were those of [53b]. The values of the mass-attenuation coefficients are those
of [53c]. All calculations for 10, 11a, and 13 were performed using the teXsan crystallographic software package
[56], while those for 16 employed the SHELXL97 program [57].
4
)
CCDC-230431-CCDC-230434 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 Center, 12 Union Road, Cambridge CB2 1EZ, UK (fax: ‡ 44-(0)1223-336033;
e-mail: deposit@ccdc.cam.ac.uk)).

Helvetica Chimica Acta Vol. 87 (2004)
1885
Table. Crystallographic Data of 10, 11a, 13, and 16
10
11a
13
16
Crystallized from
Empirical formula
MeOH
MeOH
MeCN
DMF
C14H11N3S ¥ CH4O C28H20N6Se2 ¥ 2 CH4O C28H20N6Se3 ¥ 2 H2O C32H20N6O2Se ¥ 2
C3H7NO
285.36
Formula weight [g molÀ1
Crystal color, habit
Crystal dimensions [mm]
Temp. [K]
Crystal system
Space group
]
662.39
pale-yellow, prism
713.24
745.64
colorless, plate
yellow, needle
0.05 Â 0.10 Â 0.25
160(1)
orthorhombic
P21212
yellow, prism
0.10 Â 0.12 Â 0.20
160(1)
0.02 Â 0.12 Â 0.22 0.10 Â 0.18 Â 0.25
160(1)
160(1)
monoclinic
P21/c
triclinic
triclinic
≈
≈
P1
P1
Z
2
4
2
2
Reflections for cell
determination
2q Range for cell
determination [8]
20094
130251
23666
75744
4
52
4
55
4
60
4 60
Unit-cell parameters a [ä] 6.8860(1)
b [ä] 9.9602(2)
12.5727(2)
13.8628(2)
16.7361(3)
90
102.2947(6)
90
2850.08(8)
1.544
2.632
17.3474(2)
18.1483(3)
4.3127(1)
90
90
90
1357.75(4)
1.744
4.100
f and w
60
7.6275(1)
11.4277(1)
20.8212(3)
74.2308(5)
83.6393(6)
76.9206(6)
1698.91(4)
1.457
c [ä] 10.1304(2)
a [8]
b [8]
g [8]
88.9010(9)
85.286(1)
85.2725(8)
V [ä3] 690.04(2)
Dx [g cmÀ3
]
1.373
0.233
m(MoKa) [mmÀ1
Scan type
]
1.160
f and w
60
w
f and w
55
2q(max) [8]
52
Transmission factors
(min; max)
0.914; 1.000
0.593; 0.789
0.471; 0.802
0.830; 0.905
Total reflections measured 11349
64492
6525
31729
3957
47492
9887
Symmetry-independent
reflections
2680
Reflections with I > 2s(I)
Parameters refined;
restraints
2126
193; 0
4892
378; 0
3422
190; 0
6807
523; 206
R(F) [I > 2s(I) reflections] 0.0432
0.0431
0.0291
0.0435
wR(F) [I > 2s(I)
reflections]
0.04480.0452
0.0291
0.1142 (on
F2,
all reflections)
a
Weights: p in
0.005
1.955
0.015
0.015
1.147
)
w ˆ [s2(Fo) ‡ (pFo)2]À1
Goodness of fit
Secondary extinction
coefficient
1.755
2.2(7) Â 10À7
1.039
Final Dmax /s
D1 (max; min) [e ¥ äÀ3
0.0001
0.24; À 0.23
0.0005
0.76; À 0.54
0.001
0.57; À 0.43
0.001
0.58; À 0.74
]
a) w ˆ [s2(Fo2) ‡ (0.0526P)2 ‡ 0.4229P]À1, where P ˆ (Fo2 ‡ 2Fc2)/3.
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Received February 11, 2004