K. Aghapoor et al. / Journal of Organometallic Chemistry 743 (2013) 170e178
171
NH2
NH2
O
O
R'
N
N
R'
BiCl /SiO2 (5 mol%)
3
+
CH OH / RT
3
R
Z
R''
R
Z
R''
1a - r
Z = CH, N
1
1
1
1
1
1
1
a: R=H;
b: R=Me;
c: R=Cl;
d: R=NO
e: R=H;
f: R=Ph-CO;
g: R=COOH;
R'=R"=Ph; Z=CH
1h: R=H;
R'=R"=4-(MeO)-Ph; Z=CH
R'=R"=4-(MeO)-Ph; Z=CH
R'=R"=4-(MeO)-Ph; Z=CH
R'=R"=4-(MeO)-Ph; Z=CH 1q: R=NO
R'=R"=4-(MeO)-Ph; Z=N
1r: R=H;
1n: R=H;
1o: R=Me;
1p: R=Cl;
R'=Ph; R"=H; Z=CH
R'=Ph; R"=H; Z=CH
R'=Ph; R"=H; Z=CH
R'=Ph; R"=H; Z=CH
R'=Ph; R"=H; Z=N
R'=R"=Ph; Z=CH 1i: R=Me;
R'=R"=Ph; Z=CH 1j: R=Cl;
R'=R"=Ph; Z=CH 1k: R=NO
R'=R"=Ph; Z=N
R'=R"=Ph; Z=CH 1m: R=Ph-CO; R'=R"=4-(MeO)-Ph; Z=CH
R'=R"=Ph; Z=CH
2
;
2
;
2
;
1l: R=H;
3 2
Scheme 1. Condensation of 1,2-dicarbonyls with 1,2-diamines catalyzed by BiCl /SiO .
Fisons instrument. Substrates are commercially available and used
1H, COOH); 13C NMR (125 MHz, CDCl
3
)
d
128.22 (2C), 128.23,
without further purification.
128.93, 129.11, 129.76, 129.79 (2C), 131.92, 132.05, 138.63, 140.41,
þ
143.04,154.17,154.76,167.77; MS (EI), m/z (rel. intensity %) 326 (M ,
100), 178 (40), 103 (65), 77 (40).
2.2. Preparation of BiCl
3 2
/SiO catalyst
2
.4.3. 6-Benzoyl-2,3-bis(4-methoxyphenyl)quinoxaline (1m)
A total of 30 g of silica gel (300e400 mesh) were activated by
refluxingwith 150mLof6mol L hydrochloricacidunderstirringfor
1
ꢀ1
H NMR (500 MHz, CDCl
3
) d 3.82 (s, 3H), 3.85 (s, 3H), 6.87 (t, 4H),
7.49e7.55 (m, 6H), 7.60e7.63 (t, 1H), 7.89 (d, 2H), 8.21 (s, 2H), 8.47
2
4 h. Then the activated silica gel was filtered and washed with
13
ꢁ
(s, 1H); C NMR (125 MHz, CDCl3)
2C), 129.37 (2C), 129.41 (2C), 130.05, 131.11, 131.16, 131.35 (2C),
32.27 (2C), 132.64, 137.26, 137.71, 139.91, 142.81, 154.06, 154.59,
d 55.26 (2C), 113.81 (3C), 128.42
doubly distilled water to neutral and dried under vacuum at 70 C for
(
1
2
4 h.
Bismuth(III) chloride (1.575 g, 5 mmol) was added to a sus-
pension of activated silica gel (17.5 g) in toluene (30 mL). The
mixture was stirred at room temperature overnight and filtered off.
þ
160.39, 160.54, 195.71; MS (EI), m/z (rel. intensity %) 446 (M , 10),
3
41 (10), 208 (15), 133 (35), 105 (100), 77 (50).
The solid was washed with ethanol and filtered off. The obtained
ꢁ
2.4.4. 6-Chloro-2-phenylquinoxaline (1ptrans)
solid was dried at 120 C under vacuum for 5 h to furnish BiCl
3
/SiO
2
1
3
H NMR (500 MHz, CDCl ) d 7.51e7.58 (m, 3H), 7.71 (dd, J 2.3 and
as a white free-flowing powder (6.1 wt% of eOeBiOCl species as
determined by TGA and 5.0 mol% of Bi as determined by Atomic
Absorption Spectrophotometry). Characterization details of the
catalyst are given in our previous work [17].
8
9
.95 Hz,1H), 8.07 (d, J 8.8 Hz,1H), 8.10 (d, J 3.15 Hz,1H), 8.17 (m, 2H),
.31 (s, 1H); C NMR (CDCl , 125 MHz): d 127.4 (2C), 128.0, 129.1
3
13
(
(
2
2C), 130.4, 130.7, 131.2, 135.2, 136.3, 140.7, 141.7, 144.0, 151.8; MS
EI), m/z (rel. intensity %) 240 (M , 100), 241 (M , 25), 242 (M , 35),
13 (12), 178 (15), 77 (10).
þ
þ
þ
2.3. General procedure for the acid-catalyzed benzo[N,N]-
heterocyclic condensation
2
.4.5. 7-Chloro-2-phenylquinoxaline (1pcis)
1
H NMR (500 MHz, CDCl
3
) d 7.47e7.54 (m, 3H), 7.60 (dd, J 2.2 and
A mixture of arene-1,2-diamine (1.2 mmol), 1,2-dicarbonyl
8
9
.9 Hz, 1H), 7.97 (d, J 8.9 Hz, 1H), 8.06 (d, J 2.2 Hz, 1H), 8.13 (m, 2H),
(
3 2
1 mmol), and 0.20 g of BiCl /SiO (5 mol %) was taken in meth-
13
3
.22 (s, 1H); C NMR (CDCl , 125 MHz): d 127.4 (2C), 128.3, 129.0
anol (5 mL) and stirred at room temperature for the appropriate
reaction time (Scheme 1). After completion of the reaction (moni-
tored by TLC using ethyl acetate/hexane (2:8 v/v) or GC),
dichloromethane was added to the reaction mixture and the cata-
lyst was recovered by filtration. The organic medium was removed
with rotary evaporator under reduced pressure. The crude products
were purified by column chromatography using ethyl acetate/
hexane (2:8 v/v) [dichloromethane/ethanol (9:1 v/v) for products
(
(
2
2C), 130.1, 130.2, 130.4, 135.8, 136.0, 139.8, 142.4, 143.1, 152.1; MS
EI), m/z (rel. intensity %) 240 (M , 100), 241 (M , 27), 242 (M , 38),
13 (12), 178 (15), 77 (10).
þ
þ
þ
2.5. Crystal structure analyses of compounds 1otrans, 1pcis, 1qtrans
and 1rcis
1
he1m] to afford pure products for analytical measurements. The
The selected crystals of 6-methyl-2-phenylquinoxaline (1otrans),
-chloro-2-phenylquinoxaline (1pcis), 6-nitro-2-phenylquinoxaline
1qtrans) and 3-phenylpyrido[2,3-b]pyrazine (1rcis) were covered
products were identified by comparison of their NMR and mass
spectra with authentic samples.
7
(
with perfluorinated oil and mounted on the top of a glass capillary
under a flow of cold gaseous nitrogen. The orientation matrix and
the unit cell dimensions were determined (Table 1) from ca. 1173
(1otrans, Stoe IPDS I), 7000 (1pcis, Stoe IPDS II), 2524 (1qtrans, Stoe
IPDS I) and 2530 (1rcis, Stoe IPDS I) reflections (graphite-mono-
2
2
.4. Selected spectroscopic data
.4.1. 6-Benzoyl-2,3-diphenylquinoxaline (1f)
1
3
H NMR (500 MHz, CDCl ) d 7.32e7.64 (m, 13H), 7.90 (d, 2H),
13
8
d
.25e8.30 (AB quartet, 2H), 8.54 (s, 1H); C NMR (125 MHz, CDCl
128.31 (3C), 128.46 (2C), 129.10, 129.24, 129.63, 129.77 (2C), 129.81,
29.84 (2C), 130.18 (2C),132.40,132.75,137.14,138.24,138.55,138.59,
3
)
chromated Mo-K
a
radiation (
l
¼ 71.073 pm). The intensities were
corrected for Lorentz and polarizations effects. In addition, ab-
sorption corrections were applied for 1pcis (numerical). The struc-
tures were solved by direct methods for all compounds using
SHELXS-97 for 1pcis and SIR-92 for 1otrans, 1qtrans and 1rcis. The
1
140.14, 142.93, 154.53, 155.07, 195.67; MS (EI), m/z (rel. intensity %)
þ
3
86 (M , 65), 385 (70), 309 (40), 152 (35), 105 (100), 77 (95).
2
structures were refined against F by full-matrix least-squares us-
2
.4.2. 6-Carboxylic acid-2,3-diphenylquinoxaline (1g)
ing the program SHELXL-97. All hydrogen atoms in all compounds
were calculated for ideal positions and were refined with a com-
mon displacement parameter. Programs used were SHELXS-97 [28],
1
3
H NMR (500 MHz, DMSO/CDCl ) d 7.30e7.36 (m, 6H), 7.50e7.51
(
d, 4H), 8.16e8.17 (d, 1H), 8.34e8.36 (d, 1H), 8.89 (s, 1H), 11.25 (br s,