Furyl(aryl)methanes and their derivatives. Part 21: Cinnnoline derivatives from 2-aminophenylbisfurylmethanes

Article abstract of DOI:10.1016/S0040-4020(00)00780-8

(Z)-4-[4-(5-Methyl-2-furyl)-3-cinnolinyl]-3-buten-2-ones and (Z)-1-[4-(5-ethyl-2-furyl)-3-cinnolinyl]-1-penten-3-ones have been obtained from 2-aminoarylbisfurylmethanes under treatment with isoamyl nitrite/trimethylchlorosilane in dry acetonitrile. Intra

Full text of DOI:10.1016/S0040-4020(00)00780-8

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 8933±8937
Furyl(aryl)methanes and their Derivatives. Part 21:1 Cinnoline
Derivatives from 2-Aminophenylbisfurylmethanes
c
Vladimir T. Abaev,a Andrey V. Gutnov,a Alexander V. Butinb, and Valerij E. Zavodnik
*
aNorth-Ossetian State University, Vatutina 46, Vladikavkaz 362025, Russian Federation
bKuban State Technological University, Moskovskaya 2, Krasnodar 350072, Russian Federation
cKarpov Institute of Physical Chemistry, Vorontsovo pole 10, Moscow 103064, Russian Federation
Received 23 June 2000; revised 9 August 2000; accepted 23 August 2000
AbstractÐ(Z)-4-[4-(5-Methyl-2-furyl)-3-cinnolinyl]-3-buten-2-ones and (Z)-1-[4-(5-ethyl-2-furyl)-3-cinnolinyl]-1-penten-3-ones have
been obtained from 2-aminoarylbisfurylmethanes under treatment with isoamyl nitrite/trimethylchlorosilane in dry acetonitrile. Intra-
molecular cyclisation and furan oxidative ring opening follow the formation of an intermediate diazonium salt. X-Ray analysis proved
the cis-con®guration of the alkene side chain. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
isoamyl nitrite and trimethylchlorosilane. There was no
noticeable tar formation under these conditions, and after
the usual workup seven cinnoline derivatives 3a±g were
isolated in high yields (Scheme 2). We suppose that cinno-
line formation is a result of intramolecular electrophilic
attack of the diazonium group at one of the furan rings,
with its subsequent cleavage.
The use of furan derivatives as versatile synthons in organic
synthesis is well documented.2 As was shown by our group,
ortho-functionalised aryldifurylmethanes are convenient
precursors in the syntheses of various condensed heterocyc-
lic systems: benzofurans,3 oxazulenes,4 azaazulenes,5
indoles5,6 and benzothiazines.6 Carbazole derivatives were
obtained in the deoxygenation reaction of 2-nitrophenyldi-
furylmethanes with triethylphosphite.7
Structures 3a±g were con®rmed by elemental analysis,
along with the presence of CvO stretching IR-spectra at
1
1680 cm21 and vinyl proton signals in H NMR-spectra
Jones' and McKinley's earlier attempt7 to substitute an
amino-group for the azido-group in 2-aminophenyldifuryl-
methanes via diazotisation in aqueous H2SO4 failed due to
tar formation in the reaction mixture. We have found that
performance of the above-mentioned reaction under anhy-
drous conditions leads to cinnoline derivatives.6 In the
present paper, we wish to present our data about this new
cinnoline synthesis from furyl(aryl)methanes.
(Jˆ12.2 Hz). The value of the coupling constant indicates
that the alkene side chain has a cis-con®guration. For further
support of the structure X-ray analysis of the compound 3g
monocrystal was made, and its ORTEP drawings are shown
below (Fig. 1).
Cis-con®guration of the side chain is in accordance with the
elecrocyclic mechanism of the furan oxidative ring clea-
vage, as shown in Scheme 2.
Results and Discussions
Experimental
2-Nitrophenyldifurylmethanes 1a±g were obtained in good
yields by the condensation of the appropriate 2-nitrobenzal-
dehydes with 2-methyl- and 2-ethylfurans in dioxane in the
presence of HClO4. Reduction of the compounds with
NaBH4 in the presence of 5% Pd/C in methanol gave 2-
aminophenyldifurylmethanes 2a±g (Scheme 1).
General
1H NMR spectra were recorded with Bruker AC-200
(200 MHz), Bruker AM-300 (300 MHz) and Tesla BS-
467A (60 MHz) spectrometers. IR-spectra were recorded
on Specord-M80 spectrophotometer. Commercial 2-methyl-
furan and 2-ethylfuran was allowed to stand over powdered
NaOH overnight, with subsequent ®ltration and distillation.
Substituted 2-nitrobenzaldehydes were obtained via nitra-
tion of the appropriate aldehydes according to the described
methods.8,9
Diazotisation was carried out in dry acetonitrile at 08C with
Keywords: diazo compounds; furans; ring transformations; cyclisation;
aromatisation; bicyclic heterocyclic compounds; nitrogen heterocycles.
* Corresponding author; e-mail: nemol@kubstu.ru
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00780-8

8934
V. T. Abaev et al. / Tetrahedron 56 (2000) 8933±8937
Scheme 1.
Scheme 2.

V. T. Abaev et al. / Tetrahedron 56 (2000) 8933±8937
8935
methane (1c). Yield 15.0 g, 78%; oil; [Found: C, 64.35; H,
6.13; N, 3.51. C21H23NO6 requires C, 65.44; H, 6.01; N,
3.63%]; dH (300 MHz, DMSO-d6) 1.18 (6H, t, Jˆ7.5 Hz,
CH2CH3), 2.56 (4H, q, Jˆ7.5 Hz, CH2CH3), 3.72 (3H, s,
OCH3), 3.87 (3H, s, OCH3), 5.90 (2H, d, Jˆ3.2 Hz,
4-HFur), 5.95 (2H, d, Jˆ3.2 Hz, 3-HFur), 6.18 (1H, s, CH),
6.69 (1H, s, 6-HAr), 7.59 (1H, s, 3-HAr).
Bis(5-methyl-2-furyl)-(4,5-ethylenedioxy-2-nitrophenyl)-
methane (1d). Yield 10.3 g, 58%; mp 138±1398C (hexane);
[Found: C, 64.15; H, 4.95; N, 3.84. C19H17NO6 requires C,
64.22; H, 4.82; N, 3.94%]; dH (300 MHz, CDCl3) 2.25 (6H,
s, CH3), 4.26±4.32 (4H, m, OCH2CH2O), 5.88 (2H, d,
Jˆ3.2 Hz, 4-HFur), 5.91 (2H, d, Jˆ3.2 Hz, 3-HFur), 6.29
(1H, s, CH), 6.80 (1H, s, 6-HAr), 7.64 (1H, s, 3-HAr).
Bis(5-ethyl-2-furyl)-(4,5-ethylenedioxy-2-nitrophenyl)-
methane (1e). Yield 15.5 g, 81%; mp 85±868C (hexane);
[Found: C, 65.92; H, 5.67; N, 3.54. C21H21NO6 requires C,
65.79; H, 5.52; N, 3.65%]; dH (300 MHz, CDCl3) 1.20 (6H,
t, Jˆ7.5 Hz, CH2CH3), 2.61 (4H, q, Jˆ7.5 Hz, CH2CH3),
4.27±4.33 (4H, m, OCH2CH2O), 5.89 (2H, d, Jˆ3.2 Hz,
4-HFur), 5.92 (2H, d, Jˆ3.2 Hz, 3-HFur), 6.30 (1H, s, CH),
6.79 (1H, s, 6-HAr), 7.65 (1H, s, 3-HAr).
Figure 1. ORTEP Drawing of 3g.
X-Ray single crystal analysis of 3g
Data were collected on a SYNTEX P-1 diffractometer using
the u/2u technique, Cu-Ka radiation (lˆ1.5418), scan
speed 3.0±12.0 deg min21, scan range 3.5±1208 and beta-
®lter. Data were corrected for Lorentz and polarisation
effects. The structure was resolved by a direct method
using shelxs-86,10 and the model was re®ned by a full-
matrix least-square technique.
Bis(5-methyl-2-furyl)-(4,5-methylenedioxy-2-nitrophenyl)-
methane (1f). Yield 10.9 g, 64%; mp 108±1098C (hexane);
[Found: C, 63.27; H, 4.53; N, 3.98. C18H15NO6 requires C,
63.34; H, 4.43; N, 4.10%]; dH (60 MHz, CDCl3) 2.17 (6H, s,
CH3), 5.80 (2H, d, Jˆ3.2 Hz, 4-HFur), 5.90 (2H, d,
Jˆ3.2 Hz, 3-HFur), 6.03 (2H, s, OCH2O), 6.23 (1H, s,
CH), 6.73 (1H, s, 6-HAr), 7.45 (1H, s, 3-HAr).
Bis(5-ethyl-2-furyl)-(4,5-methylenedioxy-2-nitrophenyl)-
methane (1g). Yield 15.9 g, 86%; mp 80±818C (hexane);
[Found: C, 64.96; H, 5.21; N, 3.83. C20H19NO6 requires C,
65.03; H, 5.18; N, 3.79%]; dH (60 MHz, CDCl3) 1.13 (6H, t,
Jˆ7.5 Hz, CH2CH3), 2.53 (4H, q, Jˆ7.5 Hz, CH2CH3), 5.83
(2H, d, Jˆ3.2 Hz, 4-HFur), 5.92 (2H, d, Jˆ3.2 Hz, 3-HFur),
6.01 (2H, s, OCH2O), 6.25 (1H, s, CH), 6.73 (1H, s, 6-HAr),
7.45 (1H, s, 3-HAr).
General procedure for 2-nitroarylbisfurylmethanes
To a solution of 2-nitrobenzaldehyde (50 mmol) and 2-
methylfuran (15 mL, 167 mmol) in dioxane (70 mL)
perchloric acid (0.5 mL) was added. The mixture was left
overnight, then poured into water (500 mL), and extracted
with warm benzene (3£50 mL); the combined organic
layers were dried with Na2SO4 and evaporated to dryness.
The oily residue was dissolved in hot hexane and the solu-
tion was ®ltered through a pad of Al2O3 and left overnight.
The crystalline product was ®ltered off and air dried.
General procedure for 2-aminoarylbisfurylmethanes
To a solution of 2-nitroarylbisfurylmethane 1 (100 mmol) in
hot methanol (70 mL), 5% palladium on charcoal (0.5 g)
was added, and then NaBH4 (1 g, 26 mmol) in small
portions. The mixture was stirred for 2 hours until the
starting compound disappeared (TLC), then poured into
water (500 mL). After extracting with warm benzene
(3£50 mL), the combined organic layers were dried with
Na2SO4 and evaporated to dryness. The oily residue was
dissolved in hot hexane, and the solution was ®ltered
through a pad of Al2O3 and left overnight in the cold to
crystallise. The crystalline product 2b was ®ltered off and
air-dried; the oily products were used in the next step with-
out further puri®cation.
Bis(5-methyl-2-furyl)-(2-nitrophenyl)methane (1a). Yield
11.0 g, 74%; mp 82±838C (hexane/CH2Cl2); [Found: C,
68.71; H, 5.12; N, 4.69. C17H15NO4 requires C, 68.68; H,
5.09; N, 4.71%]; dH (200 MHz, CDCl3) 2.23 (6H, s, CH3),
5.88 (2H, d, Jˆ3.2 Hz, 4-HFur), 5.96 (2H, d, Jˆ3.2 Hz,
3-HFur), 6.16 (1H, s, CH), 7.30 (1H, d, Jˆ7.8 Hz, 6-HAr),
7.53 (1H, dd, Jˆ7.8, 8.0 Hz, 4-HAr), 7.65 (1H, dd, Jˆ7.8,
8.0 Hz, 5-HAr), 7.95 (1H, d, Jˆ7.8 Hz, 3-HAr).
Bis(5-methyl-2-furyl)-(4,5-dimethoxy-2-nitrophenyl)-
methane (1b). Yield 12.3, 69%; mp 94±958C (methanol);
[Found: C, 63.89; H, 5.40; N, 3.91. C19H19NO6 requires C,
63.86; H, 5.36; N, 3.92%]; dH (300 MHz, DMSO-d6) 2.22
(6H, s, CH3), 3.73 (3H, s, OCH3), 3.88 (3H, s, OCH3), 5.90
(2H, d, Jˆ3.2 Hz, 4-HFur), 5.96 (2H, d, Jˆ3.2 Hz, 3-HFur),
6.16 (1H, s, CH), 6.71 (1H, s, 6-HAr), 7.60 (1H, s, 3-HAr).
Bis(5-methyl-2-furyl)-(4,5-dimethoxy-2-aminophenyl)-
methane (2b). Yield 23.9 g, 73%; oil, oxalate saltÐmp
119±1208C; [Found: C, 69.75; H, 6.51; N, 4.26.
C19H21NO4 requires C, 69.71; H, 6.47; N, 4.28%]; nmax(Nu-
jol) 3450, 3380 cm21; dH (300 MHz, DMSO-d6) 2.22 (6H, s,
Bis(5-ethyl-2-furyl)-(4,5-dimethoxy-2-nitrophenyl)-

8936
V. T. Abaev et al. / Tetrahedron 56 (2000) 8933±8937
CH3), 3.53 (3H, s, OCH3), 3.69 (3H, s, OCH3), 4.46 (2H, s,
NH2), 5.39 (1H, s, CH), 5.89 (2H, d, Jˆ3.2 Hz, 4-HFur), 5.97
(2H, d, Jˆ3.2 Hz, 3-HFur), 6.38 (1H, s, 3-HAr), 6.49 (1H, s,
6-HAr).
(1H, d, Jˆ3.2 Hz, 4-HFur), 6.39 (1H, d, Jˆ12.4 Hz,
CHvCHCO), 6.72 (1H, d, Jˆ3.2 Hz, 3-HFur), 7.09 (1H, d,
Jˆ12.4 Hz, CHvCHCO), 7.69 (1H, s, 8-HCin), 7.92 (1H, s,
5-HCin).
(Z)-1-[4-(5-Ethyl-2-furyl)-7,8-dihydro[1,4]dioxino[2,3-
g]cinnolin-3-yl]-1-penten-3-one (3e). Yield 3.17 g, 87%;
mp 113±1148C (ethyl acetate); [Found: C, 69.33; H, 5.52;
N, 7.60. C21H20N2O4 requires C, 69.22; H, 5.53; N, 7.69%];
General procedure for cinnolines
To a stirred solution of 2-aminoarylbisfurylmethane 2
(10 mmol) in acetonitrile (15 mL), trimethylchlorosilane
(2 mL, 16 mmol) and isoamyl nitrite (1.5 mL, 11 mmol)
were added successively. The mixture was stirred for an
additional 15 min, then poured into water (200 mL) and
made alkaline with solid NaHCO3. The aqueous solution
was extracted with ethyl acetate (3£50 mL), the organic
layer was separated and dried over Na2SO4. Then picric
acid (4 g, 18 mmol) in ethyl acetate (10 mL) was added to
the solution and the mixture was left overnight. The pre-
cipitated salt was ®ltered and washed with ether. Treatment
with 3% aqueous sodium hydrogen carbonate gave an easily
crystallisable oil. The crude cinnoline was ®ltered off,
washed with methanol and air dried. The product was
recrystallised from ethyl acetate.
n
max(Nujol) 1680 cm21; dH (200 MHz, CDCl3) 1.13 (3H, t,
Jˆ7.2 Hz, COCH2CH3), 1.35 (3H, t, Jˆ7.2 Hz, CH2CH3),
2.59 (2H, q, Jˆ7.2 Hz, COCH2CH3), 2.81 (2H, q, Jˆ7.2 Hz,
CH2CH3), 4.41 (4H, s, OCH2CH2O), 6.26 (1H, d, Jˆ3.2 Hz,
4-HFur), 6.41 (1H, d, Jˆ12.4 Hz, CHvCHCO), 6.73 (1H, d,
Jˆ3.2 Hz, 3-HFur), 7.06 (1H, d, Jˆ12.4 Hz, CHvCHCO),
7.66 (1H, s, 8-HCin), 7.90 (1H, s, 5-HCin).
(Z)-4-[4-(5-Methyl-2-furyl)[1,3]dioxolo[4,5-g]cinnolin-3-
yl]-3-buten-2-one (3f). Yield 2.55, 79%; mp 118±1198C
(benzene); [Found: C, 67.14; H, 4.35; N, 8.73.
C18H14N2O4 requires C, 67.08; H, 4.38; N, 8.69%]; nmax
(Nujol) 1680 cm21; dH (200 MHz, CDCl3) 2.28 (3H, s,
COCH3), 2.47 (3H, s, CH3), 4.43 (4H, s, OCH2O), 6.25
(1H, d, Jˆ3.2 Hz, 4-HFur), 6.38 (1H, d, Jˆ12.4 Hz,
CHvCHCO), 6.70 (1H, d, Jˆ3.2 Hz, 3-HFur), 6.99 (1H, d,
Jˆ12.4 Hz, CHvCHCO), 7.43 (1H, s, 8-HCin), 7.61 (1H, s,
5-HCin).
(Z)-4-[4-(5-Methyl-2-furyl)-3-cinnolinyl]-3-buten-2-one
(3a). Yield 2.20 g, 79%; mp 94±958C (benzene); [Found: C,
73.24; H, 5.19; N, 10.13. C17H14N2O2 requires C, 73.37; H,
5.07; N, 10.06%]; nmax(Nujol) 1680 cm21; dH (300 MHz,
CDCl3) 2.31 (3H, s, COCH3), 2.49 (3H, s, CH3), 6.30 (1H,
d, Jˆ3.2 Hz, 4-HFur), 6.47 (1H, d, Jˆ12.2 Hz, CHvCH±
CO), 6.80 (1H, d, Jˆ3.2 Hz, 3-HFur), 7.13 (1H, d,
Jˆ12.2 Hz, CHvCHCO), 7.75 (1H, dd, Jˆ7.8, 8.0 Hz,
7-HCin), 7.83 (1H, dd, Jˆ7.8, 8.0 Hz, 6-HCin), 8.33 (1H, d,
Jˆ7.8 Hz, 8-HCin), 8.53 (1H, d, Jˆ7.8 Hz, 5-HCin).
(Z)-1-[4-(5-Ethyl-2-furyl)[1,3]dioxolo[4,5-g]cinnolin-3-yl]-
1-penten-3-one (3g). Yield 2.91, 83%; mp 112±1138C (ben-
zene); [Found: C, 68.49; H, 5.20; N, 7.97. C20H18N2O4
requires C, 68.56; H, 5.18; N, 8.00%]; nmax(Nujol)
1680 cm21; dH (200 MHz, CDCl3) 1.12 (3H, t, Jˆ7.2 Hz,
COCH2CH3), 1.32 (3H, t, Jˆ7.2 Hz, CH2CH3), 2.57 (2H, q,
Jˆ7.2 Hz, COCH2CH3), 2.78 (2H, q, Jˆ7.2 Hz, CH2CH3),
4.41 (4H, s, OCH2O), 6.23 (1H, d, Jˆ3.2 Hz, 4-HFur), 6.39
(1H, d, Jˆ12.4 Hz, CHvCHCO), 6.69 (1H, d, Jˆ3.2 Hz,
3-HFur), 6.97 (1H, d, Jˆ12.4 Hz, CHvCHCO), 7.41 (1H, s,
8-HCin), 7.60 (1H, s, 5-HCin).
(Z)-4-[6,7-Dimethoxy-4-(5-methyl-2-furyl)-3-cinnolinyl]-
3-buten-2-one (3b). Yield 2.91 g, 86%; mp 169±1708C
(ethyl acetate); [Found: C, 67.47; H, 5.40; N, 8.30.
C19H18N2O4 C, 67.45; H, 5.36; N, 8.28%]; nmax(Nujol)
1680 cm21; dH (200 MHz, CDCl3) 2.26 (3H, s, COCH3),
2.47 (3H, s, CH3), 4.01 (3H, s, OCH3), 4.10 (3H, s, OCH3),
6.28 (1H, d, Jˆ3.2 Hz, 4-HFur), 6.40 (1H, d, Jˆ12.2 Hz,
CHvCHCO), 6.75 (1H, d, Jˆ3.2 Hz, 3-HFur), 7.10 (1H, d,
Jˆ12.2 Hz, CHvCHCO), 7.55 (1H, s, 8-HCin), 7.75 (1H, s,
5-HCin).
Supporting samples of the compounds are available
independently from Molecular Diversity Preservation
International, http://www.mdpi.org.
(Z)-1-[4-(5-Ethyl-2-furyl)-6,7-dimethoxy-3-cinnolinyl]-
1-penten-3-one (3c). Yield 3.26 g, 89%; mp 97±968C (ben-
zene); [Found: C, 68.92; H, 6.13; N, 7.75. C21H22N2O4
requires C, 68.84; H, 6.05; N, 7.65%]; nmax(Nujol)
1680 cm21; dH (200 MHz, CDCl3) 1.13 (3H, t, Jˆ7.2 Hz,
COCH2CH3), 1.36 (3H, t, Jˆ7.2 Hz, CH2CH3), 2.58 (2H, q,
Jˆ7.2 Hz, COCH2CH3), 2.81 (2H, q, Jˆ7.2 Hz, CH2CH3),
4.00 (3H, s, OCH3), 4.09 (3H, s, OCH3), 6.28 (1H, d,
Jˆ3.2 Hz, 4-HFur), 6.41 (1H, d, Jˆ12.2 Hz, CHvCHCO),
6.76 (1H, d, Jˆ3.2 Hz, 3-HFur), 7.07 (1H, d, Jˆ12.2 Hz,
CHvCHCO), 7.52 (1H, s, 8-HCin), 7.74 (1H, s, 5-HCin).
Acknowledgements
The authors are grateful to Professor Gurnos Jones for his
interest in this work and assistance in the preparation of the
manuscript.
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mp 135±1368C (ethyl acetate); [Found: C, 67.94; H, 4.91;
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