Novel synthesis of 2-aminoquinoline-3-carbaldehyde, benzo[b][1,8] naphthyridines and study of their fluorescence behavior

Article abstract of DOI:10.1002/poc.1727

A novel route was successfully developed for the synthesis of new synthons, orthoamino formyl quinoline (heterocyclic orthoaminoaldehyde) and utilized for the synthesis of series of benzonaphthyridines by Friedlaender condensation reactions with benzoylac

Full text of DOI:10.1002/poc.1727

Research Article
Received: 19 February 2010,
Revised: 3 April 2010,
Accepted: 7 April 2010,
Published online 28 September 2010 in Wiley Online Library: 2011
(wileyonlinelibrary.com) DOI 10.1002/poc.1727
Novel Synthesis of 2-aminoquinoline-3-
carbaldehyde, benzo[b][1,8]
naphthyridines and study of their
fluorescence behavior
Deepak P. Shelara, Dilip R. Biraria, Ramhari V. Rotea, Sandeep R. Patila,
Raghunath B. Tochea and Madhukar N. Jachaka
*
A novel route was successfully developed for the synthesis of new synthons, orthoamino formyl quinoline (hetero-
cyclic orthoaminoaldehyde) and utilized for the synthesis of series of benzonaphthyridines by Friedla¨nder conden-
sation reactions with benzoylacetonitrile. The benzonaphthyridines synthesized were further studied for their
fluorescence properties. Copyright ß 2010 John Wiley & Sons, Ltd.
Keywords: benzo[b][1,8] naphthyridine-3-carbonitrile; fluorescence; HOMO–LUMO; orthoamino formyl quinoline; quantum
yield
INTRODUCTION
RESULTS AND DISCUSSION
Synthesis of orthoamino formyl quinoline (heterocyclic
orthoaminoaldehyde) 7
Donor-acceptor substituted aromatic organic compounds gener-
ally have highly dipolar charge-separated excited states and are,
therefore, suitable candidates for high second-order nonlinear
optical properties[1]. Large p-conjugated systems substituted
with both a strong electron donor and acceptor exhibit enhanced
nonlinear optical (NLO) properties[2]. Pyrazolo-quinoline deriva-
tives as well as several different polymeric materials show
photoluminescence in solution. These compounds are important
because they have high fluorescence efficiencies in the blue
region and demonstrate high physical and chemical stabilities.
The starting material orthoamino formyl quinoline (heterocyclic
orthoaminoaldehyde) 7, required for the synthesis of benzo-
naphthyridines was synthesized by developing a novel route. In
the literature, compound 7 was obtained by sequence of
reactions[16–18] starting with orthoamino benzaldehyde (Fig. 1).
We have attempted the synthesis of 7 by sequence of reactions
in which orthochloro formyl quinoline 2 was obtained from
acetanilide by the literature method[19]. Thus, azidation of 2
yielded compound 3 in excellent yield. It was characterized by IR,
1H and 13C NMR and observed that it mainly exists in tetrazole
tautomer as reported by Stadlbauer et al.[20]. The attempted
catalytic hydrogenation[21] of tetrazolo[1,5-a]quinoline-4-carbal-
dehyde 3 yielded a mixture of two compounds, separated by
column and assigned structure 4 and 5 on the basis of spectral
They showed high potential for electroluminescence devices[3,4]
.
Benzo- naphthyridine derivatives are compounds showing
intense fluorescence in the blue–green region and are
considered for application as fluorescence standards[5]. It was
also noted from the literature that naphthyridine derivatives were
not only used as luminescence materials in molecular recognition
because of their rigid planer structure[6–8], but also as new drug
leaders[9,10] and anticancer active screening agents in a new drug
1
and analytical data. For instance, H NMR spectrum of 4 shows
doublet–triplet pattern at 4.9 and 5.8d corresponding to —CH2
and —OH protons, respectively. All aromatic protons show
expected chemical shifts and splitting patterns, which resemble
with the structure of 4. In this reaction, we could not observe a
hydrogenation of tetrazolo ring to amino functionality. To achieve
the synthesis of desired o-aminoaldehyde 7, the method
discovery[11,12]
.
Using these reports and our earlier communication, in
relation to fluorescence properties of dipyrazolopyridines
(DPP)[13], pyrazolopyrrolopyridine (PPP)[14] and pyridine-3-car-
bonitriles[15], herein, we report the synthesis of benzo[b][1,8]
naphthyridines 8 starting from 2-aminoquinoline-3-carbalde-
hyde 7 (heterocyclic orthoaminoaldehyde). The photophysical
properties of 8 were studied and compared absorption and
emission maxima with reference to donor and acceptor
substituents on it. The substituent effect on the performance
of these is studied by calculating highest occupied molecular
orbital (HOMO) and lowest unoccupied molecular orbital
(LUMO) energies by MOPAC-2009 to investigate the fluor-
escence properties of 8.
*
Correspondence to: M. N. Jachak, Organic Chemistry Research Center, Depart-
ment of Chemistry, K. T. H. M. College, Gangapur Road, Nashik 422002,
Maharashtra, India.
E-mail: mnjachak@hotmail.com
a
D. P. Shelar, D. R. Birari, R. V. Rote, S. R. Patil, R. B. Toche, M. N. Jachak
Organic Chemistry Research Center, Department of Chemistry, K. T. H. M.
College, Gangapur Road, Nashik 422002, Maharashtra, India
J. Phys. Org. Chem. 2011, 24 203–211
Copyright ß 2010 John Wiley & Sons, Ltd.

D. P. SHELAR ET AL.
O
O
O
NH4OH
NH2
NH2
H CNCH2CONH2
OH
NH2
N
NH2
N
MeOH,
H2SO4
O
O
H
OH
NH2
MnO2
THF
OMe
NH2
LAH,THF
N
NH2
N
N
7
Figure 1. Synthesis of orthoamino formyl quinoline by A. Godard et al.
described by Kappe et al.[22] was performed on 3. Thus
compound 3 on treatment with triphenylphosphine yielded
iminophosphorane 6. The yield of iminophosphorane 6 is found
to be maximum in chlorobenzene compared to other solvents
shown in Table 1. Hydrolysis of 6 with 80% aqueous hydrochloric
acid yielded desired 2-aminoquinoline-3-carbaldehyde 7(a-b)
(heterocyclic orthoaminoaldehyde) in 74–76% yield. The struc-
noaldehyde) with various active methylenes. Herein, we studied
the annelation of pyridine ring onto quinoline nucleus by
condensing
7 with benzoylacetonitriles. Thus, Friedla¨nder
condensation of compound 7 with methylene active nitriles
such as benzoylacetonitrile is carried out using mild base such as
piperedine in ethanol to furnish benzo[b][1,8] naphthyridine-3-
carbonitrile 8 in 74–96% yield (Scheme 2). Compounds 8 are
1
1
ture of compounds 6 and 7 are confirmed by IR, H NMR, 13C
characterized by IR, H NMR, 13C NMR, mass spectroscopy, and
NMR, mass spectroscopy and formulae are confirmed by
elemental analysis. For instance, 1H NMR spectrum of 7b showed
that singlet at 3.8d corresponds to -OCH3 protons, broad singlet
elemental analysis. Further, photophysical properties of 8 are
studied.
The compound 8 in hand shows fluorescent under fluorescence
lamp; hence we think these compounds are good candidates for
studying their photophysical properties (Fig. 2). In the beginning
we performed empirical calculations of HOMO, LUMO, and
1
at 7.3d in its H NMR corresponds to two protons of -NH2, and
singlet at 9.9d corresponds to aldehydic proton. All aromatic
protons show expected chemical shifts and splitting patterns,
which resemble with the structure of 7b. The mass spectrum of
7b reveals a molecular ion peak m/z at 202. The 13C NMR
spectrum of this compound is in agreement with the proposed
structure (Scheme 1).
HOMO–LUMO Gap using MOPAC-2009 (Version 8.331)[25,26]
.
Semi empirical study of benzo[b][1,8] naphthyridine (8)
The heterocycles which are useful as Organic Light Emitting
Diodes (OLED) should fluoresce between 400 and 700 nm and
HOMO/LUMO or ‘electron–hole’ gap is in the range of 2.7–3.0 eV,
i.e., low gap[27]. Prompted with this, we have calculated HOMO–
LUMO energies, electron–hole gap of compounds 8 using
MOPAC-2009 (Version 8.331) and are given in Table 2.
Compounds 8f, 8h, 8m, 8o, 8p, and 8q show low gap values
compared to others. The 3D picture of the benzonaphthyridines 8
is depicted in Fig. 3. In compounds 8, the chromophore nitrile
group makes facile charge delocalization and hence absorbs at
longer wavelength. The charge is more concentrated on ring D as
compared to rings A, B, and C. The donor chromophores on ring
D play an important role in increasing the electron density and
lowering the electron–hole gap.
Synthesis of Benzo[b][1,8] naphthyridines
In the earlier communication[23,24], we have studied Friedla¨nder
condensation on 5-aminopyrazole-4-carbaldehyde (orthoami-
Table 1. Solvent effect on yield
Sr. no.
Name of the solvent
Yield (%)
Time (hrs)
1
2
3
4
5
1, 2-dichlorobenzene
Chlorobenzene
Bromobenzene
Toluene:DMF (80:20) (v:v)
Diphenylether
52–58
88–96
75–80
60–65
65–70
8.5–9
4–5
5–6
6–7
4–5
Figure 2. Fluorescence under fluorescence lamp: of compound 8m,
8q, and 8r, respectively.
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Copyright ß 2010 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2011, 24 203–211

SYNTHESIS OF NEW SYNTHONS, ORTHOAMINO FORMYL QUINOLINE
O
R
R
O
DMF/POCl3
70-75 oC
CH3
H
N
H
N
Cl
(a-b)
2
(a-b)
1
R=a) H,
b) OCH3
NaN3,DMF
Stirred,14-16 h
O
O
N
CH3
R
R
OH
H
H2, Pd/C
CH3OH
PPh3
+
N
H
N
N
5
N
N
N
N
N
N
N
Chlorobenzene
Reflux
PPh3
N
N
N
4
(a-b)
(a-b)
3
6
MeOH/aq.HCl
Reflux/ 2 h
O
R
H
N
NH2
(a-b)
7
R= a) H,
b) OCH3
Scheme 1.
Another interesting feature is that halo-substituted molecules
(8a, 8b, 8e, 8j, 8k, and 8n) have less fluorescence quantum yield
than methoxy–substituted compounds (fF ¼ 0.40–0.41). This
may be due to quenching of fluorescence with halogen atoms as
the substituents. The comparative absorption and emission
spectra of compounds 8r, 8m, and 8q are graphically presented
in Fig. 4.
PHOTOPHYSICAL PROPERTIES
The UV absorption and emission properties of compounds 8 are
undertaken in polar aprotic solvent such as DMF. Fluorescence
quantum yields of each are determined by the standard literature
procedure using quinine sulphate as a reference standard[28,29]
and are given in Table 3. It is noted that fluorescence maxima of
the compounds 8 (j–r) are larger than the 8 (a–i), which may be
due to the presence of strong p-electron donor, i.e.,-OCH3 group
on ring A. Compounds 8m, 8o, and 8q show fluorescence
maxima at 510, 498, and 505 nm, respectively; this may be due to
presence of strong s–p electron and p-electron donor groups
such as di-CF3, di-OCH3 and -OCH3 which are present on ring D.
However, compounds 8i and 8r show low emission maxima at
440 and 455 nm, respectively, which may be due to presence of
electron acceptor group, i.e., -NO2 on ring D at para position.
CONCLUSION
In conclusion, we have developed a new and efficient route
for the synthesis of orthoamino-formyl-quinoline 7 and studied
its Friedla¨nder condensation with active methylene com-
pounds to obtain benzonaphthyridines 8. Thermal analysis of
compounds
8
by differential scanning colorimetry (DSC)
R1
O
R2
R3
CN
O
CN
R1
R
R
R4
H
NH2
R2
N
N
EtOH/Piperidine
reflux,2 h
N
7 (a-b)
R3
8 (a-r)
R4
Scheme 2.
J. Phys. Org. Chem. 2011, 24 203–211
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D. P. SHELAR ET AL.
Table 2. The molecular electronic properties (HOMO–LUMO energy, GAP) of the benzo[b][1,8] naphthyridine-3-carbonitrile 8(a–r)
Comp.
R
R1
R2
R3
R4
HOMO (eV)
LUMO (eV)
GAP (eV)
8a
8b
8c
8d
8e
8f
8g
8h
8i
8j
8k
8l
8m
8n
8o
8p
8q
8r
H
H
H
H
H
H
H
H
H
H
H
H
H
OCH3
H
H
H
H
H
H
H
H
OCH3
H
H
H
H
H
H
CF3
F
H
H
H
H
H
H
H
CF3
F
H
H
H
H
Cl
Br
H
H
H
H
CH3
OCH3
NO2
Cl
H
H
H
CF3
F
OCH3
H
H
H
H
H
H
CF3
F
OCH3
H
ꢀ9.466
ꢀ9.504
ꢀ9.417
ꢀ9.741
ꢀ9.633
ꢀ8.440
ꢀ9.248
ꢀ8.944
ꢀ9.740
ꢀ9.075
ꢀ9.094
ꢀ8.999
ꢀ9.283
ꢀ9.185
ꢀ8.400
ꢀ8.826
ꢀ8.738
ꢀ9.163
ꢀ1.991
ꢀ2.004
ꢀ1.887
ꢀ2.214
ꢀ2.075
ꢀ1.724
ꢀ1.834
ꢀ1.827
ꢀ2.209
ꢀ1.948
ꢀ1.960
ꢀ1.847
ꢀ2.164
ꢀ2.024
ꢀ1.716
ꢀ1.825
ꢀ1.821
ꢀ2.181
7.475
7.500
7.530
7.527
7.558
6.716
7.414
7.117
7.531
7.127
7.134
7.152
7.119
7.161
6.684
7.001
6.917
6.982
H
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
Br
H
H
H
H
CH3
OCH3
NO2
H
H
GAP ¼ ELUMOꢀEHOMO
.
revealed that they are thermally stable compounds up to
3508C. The fluorescent quantum yields of compounds 8 lie
between fF ¼ 0.2–0.4. The absorption and emission maxima
of compounds 8 depend upon the nature of substituents on
the D ring. Thus, donor chromophores on ring D, such as di-
CF3, di-OCH3, and -OCH3 (compounds 8m, 8o, and 8q) are
show red shift (bathochromic shift) and acceptor chromophore
in compound -NO2 (8r) shifts the emission maxima to lower
wavelength (blue shift). From these studies, we also reveal that
benzo[b][1,8] naphthyridines, which shows low electron–hole
gap values (e.g., 8f, 8h, 8m, 8o, 8p, and 8q) have high
emission as well as high quantum yields (except 8r). While
compounds have high electron–hole gap (e.g., 8b, 8e, 8i, and
8n), show low emission and low quantum yields and are in
agreement with theoretical observations.
EXPERIMENTAL
General
Melting points are determined on a Gallenkamp melting point
apparatus, Mod. MFB595 in open capillary tubes and are
uncorrected. 1H and 13C NMR Spectra are recorded on Varian
XL-300 spectrometer (300 MHz). Chemical shifts are reported
in ppm from internal tetramethylsilane standard and are given in
Figure 3. 3D picture of benzo[b][1,8] naphthyridine-3-carbonitrile 8(a–i) and 8(j–r)
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SYNTHESIS OF NEW SYNTHONS, ORTHOAMINO FORMYL QUINOLINE
Table 3. The photophysical data for electronic absorption (UV lMax.), fluorescence (Em lMax.), and quantum yield (fF) of
benzo[b][1,8] naphthyridine-3-carbonitriles 8 (a–r) for 0.1 M Conc. in DMF as the solvent at 258C.
8
R
R1
R2
R3
R4
UV lMax./nm
Em lMAX./nm
fF
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
H
H
H
H
H
H
H
H
H
H
H
H
H
OCH3
H
H
H
H
H
H
H
H
OCH3
H
H
H
H
H
H
CF3
F
H
H
H
H
H
H
H
CF3
F
H
H
H
H
Cl
Br
H
H
H
H
CH3
OCH3
NO2
Cl
H
H
H
CF3
F
OCH3
H
H
H
H
H
H
CF3
F
OCH3
H
386
391
386
384
380
382
388
382
376
394
385
388
382
377
389
385
387
380
471
468
476
482
472
482
478
484
440
483
484
490
510
482
498
495
505
455
0.31
0.30
0.33
0.35
0.31
0.36
0.34
0.37
0.27
0.36
0.37
0.39
0.41
0.36
0.40
0.39
0.40
0.29
H
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
Br
H
H
H
H
CH3
OCH3
NO2
H
H
d unit. The solvents for NMR spectra are deuterio-chloroform
(CDCl3) and deuterio-dimethylsulphoxide (DMSO-d6). Infrared
spectra are taken on Shimadzu FTIR-408 instrument in potassium
bromide pellets. UV spectra are recorded on a Shimadzu UV-1601
UV–VIS Spectrophotometer. Fluorescence spectra are recorded
using RF-5301 PC Spectrofluorophotometer; compounds for UV
and fluorescence measurements are dissolved in DMF. UV and
fluorescence scan are recorded from 200 to 600 nm. Elemental
analyses are performed on a Hosli CH-Analyzer and are
within ꢁ 0.3 of the theoretical percentage. High-resolution mass
spectra are obtained with a Mat 112 Varian Mat Bremen (70 eV)
mass spectrometer. Solutions are concentrated in a rotary
evaporated under reduced pressure. All reactions are monitored
by thin layer chromatography, carried out on 0.2 mm silica gel 60
F254 (Merck) plates using UV light (250 and 400 nm) and
Fluorescence light (400 and 600 nm) for detection. Common
reagents grade chemicals are either commercially available and
are used without further purification or prepared by standard
literature procedures. The GAMESS software is used for
HOMO–LUMO, heat of formation, etc. by semi-empirical PM6
methods.
Synthesis
Procedure for the synthesis of 2-chloroquinolie-3-carbaldehyde
(2a,b)
To an ice-cooled solution of N, N-dimethylformamide (11.6 mL,
0.15 mol) was added dropwise with stirring phosphorous
oxychloride (32.3 mL, 0.35 mol). Acetanilide (6.75 g, 0.05 mol)
was then added and the reaction temperature increased to 758C
and stirred for 16–17 h. The reaction mixture was poured into
Figure 4. The comparative absorption (UV lMax.) and fluorescence (Em lMax) spectra of compounds 8r, 8q, and 8m, respectively.
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D. P. SHELAR ET AL.
ice–water (300 mL) and stirred for 0.5 h at < 108C. The
precipitated solid was collected by filtration and washes well
with water (100 mL), air-dried and recrystalized from acetonitrile
or ethyl acetate to afford yellow needles.
evaporated under reduced pressure. Obtained mixture was
separated by column eluting with toluene: acetone (10: 9) (v/v)
(Tetrazolo[1,5-a]quinoline-4-yl)methanol (4). Yield: 1.12 g (56%),
recrystalized from ethanol to afford white needle; mp 198–2018C.
IR (KBr): 3342 s, 3064 m, 1620 s, 1533 s, 1080 m cmꢀ1 1H NMR
.
2-Chloroquinolie-3-carbaldehyde 2a. Yield: 6.25 g (68%), recrysta-
lized from acetonitrile to afford faint-yellow needles; mp 148–
1498C. IR (KBr): 2975 m, 2840 w, 1690 s, 1618 s, 1520 s,
(300 MHz CDCl3) d: 4.99 (d, 2H, J ¼ 5.4 Hz, CH2), 5.85 (t, 1H,
J ¼ 5.4 Hz, OH), 7.78 (dd, 1H, J ¼ 8.1 and 8.4 Hz, Ar-H), 7.82 (dd, 1H,
J ¼ 8.1 and 8.4 Hz, Ar-H), 8.20 (s, 1H, Ar-H), 8.29 (d, 1H, J ¼ 8.1 Hz,
Ar-H), 8.62 (d, 1H, J ¼ 8.1 Hz, Ar-H). 13C NMR (75 MHz CDCl3) d:
58.2, 115.9, 121.4, 123.9, 127.1, 128.0, 129.0, 129.1, 130.5, 145.8.
MS (70 eV) m/z (%): 200 (45) [Mþ], 172 (68), 142 (90), 115 (82), 89
(84). Anal. Calcd. for C10H8N4O (200.20): C, 60.00; H, 4.00; N,
28.00%. Found: C, 60.03; H, 4.00; N, 28.05%.
1
1480 m cmꢀ1. H NMR (300 MHz, CDCl3) d: 7.82 (dd, 1H, J ¼ 8.2
and 8.5 Hz, Ar-H), 7.92 (dd, 1H, J ¼ 8.5 and 8.1 Hz, Ar-H), 8.12 (d, 1H,
J ¼ 8.2 Hz, Ar-H), 8.23 (d, 1H, J ¼ 8.1 Hz, Ar-H), 8.85 (s, 1H, Ar-H),
10.54 (s, 1H, CHO). Anal. Calcd. for C10H6ClNO (191.61): C, 62.82; H,
3.14; N, 7.32%. Found: C, 62.88; H, 3.12; N, 7.34%.
2-Chloro-6-methoxyquinoline-3-carbaldehyde 2b. Yield: 6.72 g
(69%), recrystalized from acetonitrile to afford dark yellow
needle; mp 145–1468C. IR (KBr): 2960 m, 2825 w, 1685 s, 1622 s,
4-Methyltetrazolo[1,5-a]quinoline (5). Yield: 0.377 g (38%), recrys-
talized from ethanol to afford white solid; mp 181–1848C. IR (KBr):
1
1528 s, 1490 m, 1018 s cmꢀ1. H NMR (300 MHz CDCl3) d: 3.93 (s,
3043 m, 2949 m, 1615 s, 1529 s, 1463 m, 763 s cmꢀ1 1H NMR
.
3H, OCH3), 7.54 (d, 1H, J ¼ 8.2 Hz, Ar-H), 7.65 (s, 1H, Ar-H), 8.15 (d,
1H, J ¼ 8.2 Hz, Ar-H), 8.95 (s, 1H, Ar-H), 10.62 (s, 1H, CHO). Anal.
Calcd. for C11H8ClNO2 (221.64): C, 59.72; H, 3.61; N, 6.33%.
Found:C, 59.75; H, 3.60; N, 6.35%.
(300 MHz CDCl3) d: 2.69 (s, 3H, CH3), 7.77 (dd, 1H, J ¼ 7.2 and
7.8 Hz, Ar-H), 7.90 (dd, 1H, J ¼ 7.2 and 8.4 Hz, Ar-H), 8.05 (s, 1H, Ar-
H), 8.13 (d, 1H, J ¼ 7.8 Hz, Ar-H), 8.58 (d, 1H, J ¼ 8.4 Hz, Ar-H). 13
C
NMR (75 MHz CDCl3) d: 16.7, 116.0, 122.6, 124.1, 128.1, 128.6,
128.9, 130.3, 131.1, 148.0. MS (70 eV) m/z (%): 184 (42) [Mþ], 155
(92), 129 (76), 115 (88), 102 (52), 77 (48). Anal. Calcd. for C10H8N4
(184.20): C, 65.21; H, 4.34; N, 30.43%. Found: C, 65.19; H, 4.35; N,
30.44%.
Procedure for the synthesis of tetrazolo [1,5-a]quinoline-4-
carbaldehyde (3a,b)
A solution of 2-chloroquinoline-3-carbaldehyde (2a-b) (0.01 mol)
and sodium azide (0.01 mol) in 15 ml DMF was stirred at 558C for
the 8 h (TLC Check). Then the solution was poured into cold water
(50 mL) and stirred for 30 min. The obtained solid was filtered,
washed with cold water (100 mL), dried and recrystallized by
Ethanol: DMF (40:60) (v:v)
Procedure for the synthesis of 3-formyl-2-
(triphenylphosphoranylideneamino)-quinoline (6a,b)
A solution of the appropriate tetrazolo [1,5-a]quinoline-4-
carbaldehyde (3a-b) (0.01 mol) and triphenylphosphine
(0.02 mol) in chlorobenzene (25 mL) was heated under reflux
for the 8 h (TLC Check). The solvent was removed in vacuum; the
residue was triturated with cyclohexane (50 mL) to remove excess
triphenylphosphine, and after standing 24 h. Product was filtered
by suction and recrystallized from the dimethylformamide.
Tetrazolo[1,5-a]quinoline-4-carbaldehyde (3a). Yield: 1.82 g (91%),
recrystalized from ethanol: DMF (40:60) to afford silver needle;
mp 245–2478C. IR (KBr): 3047 m, 2845 w, 1702 s, 1608 s, 1535 s,
1455 m, 1168 m, 1079 m, 1061 m cmꢀ1. 1H NMR (300 MHz DMSO-
d6) d: 7.88 (dd, 1H, J ¼ 8.1 and 8.4 Hz, Ar-H), 8.12 (dd, 1H, J ¼ 8.4
and 8.1 Hz, Ar-H), 8.48 (d, 1H, J ¼ 8.1 Hz, Ar-H), 8.70 (d, 1H,
J ¼ 8.1 Hz, Ar-H), 9.01 (s, 1H, Ar-H), 10.41 (s, 1H, CHO). 13C NMR
(75 MHz CDCl3) d: 116.4, 121.3, 122.8, 126.4, 128.6, 129.5, 131.6,
134.3, 139.7, 187.4. MS (70 eV) m/z (%): 198 (20) [Mþ], 170 (100),
143 (80), 115 (75), 88 (74), 63 (77). Anal. Calcd. for C10H6N4O
(198.18): C, 60.60; H, 3.03; N, 28.28%. Found: C, 60.55; H, 3.06; N,
28.25%.
3-Formyl-2-(triphenylphosphoranylideneamino)-quinoline
(6a). Yield: 3.88 g (89%), recrystalized from DMF to afford yellow
solid; mp 233–236 8C. IR (KBr): 3056 m, 2852 w, 1692 s, 1615 s,
1
1583 s, 1410 m, 723 s cmꢀ1. H NMR (300 MHz DMSO-d6) d: 7.32
(dd, 1H, J ¼ 8.3 and 8.5 Hz, Ar-H), 7.45 (dd, 1H, J ¼ 8.5 and 8.1 Hz,
Ar-H), 7.62 (s, 5H, Ar-H), 7.77 (s, 5H, Ar-H), 7.78 (d, 1H, J¼ 8.3 Hz, Ar-
H), 7.89 (s, 5H, Ar-H), 8.01 (d, 1H, J ¼ 8.1 Hz, Ar- H), 8.36 (s, 1H, Ar-
H), 11.00 (s, 1H, CHO). MS (70 eV) m/z (%): 432 (26) [Mþ], 403 (38),
277 (94), 249 (18), 199 (88),183 (89), 171 (28), 152 (86), 107 (38), 77
(90), 51 (82). Anal. Calcd. for C28H21N2OP (432.46): C, 77.77; H, 4.86;
N, 6.48%. Found: C, 77.75; H, 4.88; N, 6.49%.
7-Methoxytetrazolo[1,5-a]quinoline-4-carbaldehyde (3b). Yield: 1.91 g
(83%), recrystalized from Ethanol: DMF (20:80) to afford off-white
prism; mp 232–2358C. IR (KBr): 3081 m, 3016 m, 2830 w, 1696 s,
1626 s, 1487 s, 1159 m, 1057 m cmꢀ1. 1H NMR (300 MHz DMSO-d6)
d: 4.06 (s, 3H, OCH3), 7.50 (d, 1H, J ¼ 8.7 Hz, Ar-H), 8.04 (s, 1H, Ar-H),
8.37 (d, 1H, J ¼ 8.7 Hz, Ar-H), 8.91 (s, 1H, Ar-H), 10.35 (s, 1H, CHO).
Anal. Calcd. for C11H8N4O2 (228.21): C, 57.89; H, 3.50; N, 24.56%.
Found: C, 57.92; H, 3.47; N, 24.55%.
6-Methoxy-3-formyl-2-(triphenylphosphoranylideneamino)-quino-
line (6b). Yield: 4.48 g (95%), recrystalized from DMF to afford
yellow solid; mp 195–1988C. IR (KBr): 3016 m, 2985 m, 2837 w,
1696 s, 1626 s, 1588 s, 1422 m, 1022 s cmꢀ1 1H NMR (300 MHz
.
DMSO-d6) d: 3.88 (s, 3H, OCH3), 6.81 (d, 1H, J ¼ 8.2 Hz, Ar-H), 7.39
(s, 1H, Ar-H), 7.64 (s, 5H, Ar-H), 7.71 (s, 5H, Ar-H), 7.75 (d, 1H,
J ¼ 8.2 Hz, Ar-H), 7.85 (s, 5H, Ar-H), 8.48 (s, 1H, Ar-H), 10.95 (s, 1H,
CHO). MS (70 eV) m/z (%): 462 (52) [Mþ], 433 (68), 390 (48), 357
(46), 216 (49), 183 (56), 51 (12). Anal. Calcd. for C29H23N2O2P
(462.48): C, 75.32; H, 4.97; N, 6.06%. Found:C, 75.31; H, 4.95; N,
6.08%.
Procedure for the Synthesis of (tetrazolo [1,5-a]quinoline-4-
yl)methanol (4) and 4-methyl tetrazolo[1,5-a]quinoline (5)
A
solution of appropriate tetrazolo [1,5-a]quinoline-4-
carbaldehyde (3a) (0.01 mol) in MeOH (300 mL) was shaken with
10% Pd/C (400 mg) in an atmosphere of H2 (2 atm.) for 10 h. The
catalyst was removed by filtration and the solvent was
wileyonlinelibrary.com/journal/poc
Copyright ß 2010 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2011, 24 203–211

SYNTHESIS OF NEW SYNTHONS, ORTHOAMINO FORMYL QUINOLINE
General procedure for the synthesis of 2-aminoquinoline-3-
carbaldehyde (7a,b)
1H NMR (300 MHz CDCl3) d: 7.46 (dd, 1H, J¼ 8.2 and 8.6 Hz, Ar-H),
7.52 (d, 2H, J ¼ 8.3 Hz, Ar-H), 7.77 (dd, 1H, J ¼ 8.6 and 8.1 Hz, Ar-H),
7.92 (d, 1H, J ¼ 8.2 Hz, Ar-H), 8.08 (d, 1H, J ¼ 8.1 Hz, Ar H), 8.22 (d,
2H, J ¼ 8.3 Hz, Ar-H), 9.23 (s, 2H, Ar-H). MS (70 eV) m/z (%): 359 (68)
[Mþ], 361 (66) [M þ 2], 333 (72), 201 (52), 183 (54), 155 (58), 152
(59), 84 (29). Anal. Calcd. for C19H10N3Br (360.20): C, 63.50; H, 2.78;
N, 11.69%. Found: C, 63.52; H, 2.80; N, 11.72%.
A mixture of 3-formyl-2-(triphenylphosphoranylideneamino)-
quinoline (0.01 mol) in 0.5 N hydrochloric acid (20 mL) and
methanol (5 mL) was heated under reflux for 2 h. After cooling to
room temperature, the precipitated triphenylphosphaneoxide
was removed by filtration and the filtrate was brought up to pH
11 with 2 N sodium hydroxide solution. The resulting precipitate
was filtered and recrystallized from ethanol.
2-Phenylbenzo[b][1,8] naphthyridine-3-carbonitrile (8c). Yield:
0.254 g (88%), recrystalized from ethanol to afford yellow solid;
.
mp 117–1208C. IR (KBr): 3024 m, 2229 s, 1648 s cmꢀ1 1H NMR
(300 MHz CDCl3) d: 7.21–7.32 (m, 5H, Ar-H), 7.33 (dd, 1H, J ¼ 8.3
and 8.5 Hz, Ar-H), 7.63 (dd, 1H, J ¼ 8.5 and 8.1 Hz, Ar-H), 7.18 (d, 1H,
J ¼ 8.3 Hz, Ar-H), 8.48 (d, 1H, J ¼ 8.1 Hz, Ar-H), 9.22 (s, 2H, Ar-H). MS
(70 eV) m/z (%): 281 (100) [Mþ], 255 (39), 199 (25), 177 (31), 154
(20), 141 (60), 127 (56), 105 (66), 84 (65), 77 (88), 56 (82). Anal.
Calcd. for C19H11N3 (281.31): C, 81.13; H, 3.91; N, 14.94%. Found: C,
81.16; H, 3.90; N, 14.90%.
2-Aminoquinoline-3-carbaldehyde (7a). Yield: 1.28 g (74%), recrys-
talized from ethanol to afford yellow crystals; mp 195–1978C. IR
(KBr): 3126 m, 3055 m, 2924 m, 2852 w, 1678 s, 1631 s, 1186 s,
1118 s cmꢀ1. 1H NMR (300 MHz DMSO-d6) d: 7.29 (dd, 1H, J ¼ 8.2
and 8.6 Hz, Ar-H), 7.32 (bs, 2H, NH2), 7.52 (dd, 1H, J ¼ 8.6 and
8.1 Hz, Ar-H), 7.68 (d, 1H, J ¼ 8.2 Hz, Ar-H), 7.87 (d, 1H, J ¼ 8.1 Hz,
Ar-H), 8.72 (s, 1H, Ar-H), 10.04 (s, 1H, CHO). 13C NMR (75 MHz
CDCl3) d: 120.1, 122.3, 124.0, 126.7, 129.3, 131.6, 141.6, 145.5,
159.7, 194.6. MS (70 eV) m/z (%): 172 (86) [Mþ], 144 (98), 127 (49),
117 (86), 89 (87), 77 (56). Anal. Calcd. for C10H8N2O (172.18): C,
69.76; H, 4.65; N, 16.27%. Found: C, 69.77; H, 4.68; N, 16.28%.
2-(3,5-Bis(trifluoromethyl)phenyl)benzo[b][1,8] naphthyridine-3-
carbonitrile (8d). Yield: 0.394 g (94%), recrystalized from ethanol
to afford yellow solid; mp 94–978C. IR (KBr): 3028 m, 2220 s,
1649 s cmꢀ1. 1H NMR (300 MHz CDCl3) d: 7.32 (dd, 1H, J ¼ 8.3 and
8.7 Hz, Ar-H), 7.67 (dd, 1H, J ¼ 8.7 and 8.5 Hz, Ar-H), 7.82 (d, 1H,
J ¼ 8.3 Hz, Ar-H), 8.10 (d, 1H, J ¼ 8.5 Hz, Ar-H), 8.42 (s, 1H, Ar-H),
9.24 (s, 2H, Ar-H), 9.47 (s, 2H, Ar-H). MS (70 eV) m/z (%): 417 (48)
[Mþ], 348 (42), 277 (84), 241 (49), 213 (32), 199 (36), 183 (35), 152
(34), 84 (22), 77 (62), 44 (89). Anal. Calcd. for C21H9N3F6 (417.31): C,
60.43; H, 2.15; N, 10.07%. Found: C, 60.45; H, 2.12; N, 10.10%.
2-Amino-6-methoxyquinoline-3-carbaldehyde (7b). Yield: 1.54 g
(76%), recrystalized from ethanol to afford yellow solid; mp
168–1728C. IR (KBr): 3329 m, 3265 m, 3045 m, 2850 w, 1673 s,
1
1025 s cmꢀ1. H NMR (300 MHz DMSO-d6) d: 3.88 (s, 3H, OCH3),
6.89 (d, 1H, J ¼ 8.4 Hz, Ar-H), 6.92 (s, 1H, Ar-H), 7.38 (bs, 2H, NH2),
7.76 (d, 1H, J ¼ 8.4 Hz, Ar-H), 8.58 (s, 1H, Ar-H), 9.94 (s, 1H, CHO).
13C NMR (75 MHz CDCl3) d: 59.3, 118.5, 119.0, 124.7, 125.3, 128.6,
140.3, 141.7, 155.2, 159.7, 194.6. MS (70 eV) m/z (%): 202 (94) [Mþ],
174 (84), 145 (22), 131 (62), 77 (44), 51 (40), 31 (48). Anal. Calcd. for
C11H10N2O2 (202.21): C, 65.34; H, 4.95; N, 13.46%. Found: C, 65.32;
H, 4.98; N, 13.45%.
2-(3,5-Difluorophenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8e). Yield: 0.289 g (91%), recrystalized from ethanol to afford
green solid; mp 135–1388C. IR (KBr): 3004 m, 2233 s, 1613 s cmꢀ1
.
1H NMR (300 MHz CDCl3) d: 7.46 (dd, 1H, J¼ 8.2 and 8.5 Hz, Ar-H),
7.69 (dd, 1H, J ¼ 8.5 and 8.1 Hz, Ar-H), 7.90 (d, 1H, J ¼ 8.2 Hz, Ar-H),
8.18 (d, 1H, J ¼ 8.1 Hz, Ar-H), 8.24 (s, 1H, Ar-H), 8.52 (s, 2H, Ar-H),
9.23 (s, 2H, Ar-H). 13C NMR (75 MHz CDCl3) d: 97.3, 112.7, 118.1,
119.6, 120.7, 126.5, 127.8, 128.4, 129.5, 129.8, 135.1, 138.5, 142.7,
146.1, 157.2, 160.1, 161.2. MS (70 eV) m/z (%): 317 (92) [Mþ], 291
(29), 159 (34), 141 (66), 127 (23), 113 (31), 84 (21), 63 (18), 44 (48).
Anal. Calcd. for C19H9N3F2 (317.29): C, 71.92; H, 2.83; N, 13.24%.
Found: C, 71.95; H, 2.85; N, 13.22%.
Procedure for the synthesis of benzo[b][1,8] naphthyridine-3-
carbonitrile 8 (a–r)
A
solution of
7
(0.001 mol) and 3-(4-chlorophenyl)-3-
oxopropanenitrile (0.001 mol) in ethanol (10 mL) containing
catalytic amount of piperidine was refluxed for 8 h. Completion
of the reaction was monitored by thin layer chromatography
(TLC). The mixture was then cooled to room temperature; the
separated solid product was collected by suction filtration,
washed with pet-ether, dried, and recrystallized from ethanol.
2-(2,5-Dimethoxyphenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8f). Yield: 0.308 g (90%), recrystalized from ethanol to afford
yellow solid; mp 125–1288C. IR (KBr): 3029 m, 2212 s, 1646 s,
2-(4-Chlorophenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8a). Yield: 0.286 g (90%), recrystalized from ethanol to afford
faint blue solid; mp 130–1338C. IR (KBr): 3021 m, 2219 s,
1022 m cmꢀ1 1H NMR (300 MHz DMSO-d6) d: 3.60 (s, 6H, 2 x
.
1
1643 s cmꢀ1. H NMR (300 MHz CDCl3) d: 7.59 (d, 2H, J ¼ 8.7 Hz,
OCH3), 7.12 (d, 1H, J ¼ 9.3 Hz, Ar-H), 7.16 (dd, 1H, J ¼ 2.3 and
9.3 Hz, Ar-H), 7.24 (d, 1H, J ¼ 2.3 Hz, Ar-H), 7.39 (dd, 1H, J ¼ 8.3 and
8.7 Hz, Ar-H), 7.78 (dd, 1H, J ¼ 8.7 and 8.1 Hz, Ar-H), 7.93 (d, 1H,
J ¼ 8.3 Hz, Ar-H), 8.12 (d, 1H, J ¼ 8.1 Hz, Ar-H), 9.12 (s, 2H, Ar-H).
Anal. Calcd. for C21H15N3O2 (341.36): C, 73.90; H, 4.39; N, 12.31%.
Found: C, 73.92; H, 4.40; N, 12.30%.
Ar-H), 7.74 (dd, 1H, J ¼ 8.2 and 8.7 Hz, Ar-H), 7.91 (dd, 1H, J ¼ 8.7
and 8.1 Hz, Ar-H), 8.17 (d, 1H, J ¼ 8.2 Hz, Ar-H), 8.20 (d, 2H,
J ¼ 8.7 Hz, Ar-H), 8.44 (d, 1H, J ¼ 8.1 Hz, Ar-H), 8.96 (s, 2H, Ar-H). 13
C
NMR (75 MHz CDCl3) d: 98.2, 112.7, 120.8, 126.1, 127.4, 128.3,
129.4, 129.7, 130.1, 130.4, 132.4, 134.2, 137.4, 142.5, 146.7, 157.2,
159.7. MS (70 eV) m/z (%): 315 (82) [Mþ], 317 (29) [M þ 2], 280 (42),
172 (23), 158 (22), 140 (52), 127 (50), 44 (76), 31 (89). Anal. Calcd.
for C19H10N3Cl (315.76): C,72.38; H, 3.17; N, 13.33%. Found: C,
72.40; H, 3.18; N, 13.14%.
2-4-Tolylbenzo[b][1,8] naphthyridine-3-carbonitrile (8g). Yield:
0.264 g (89%), recrystalized from ethanol to afford yellow solid;
mp 87–90 8C.
IR (KBr): 3004 m, 2220 s, 1640 s cmꢀ1. 1H NMR (300 MHz CDCl3)
d: 2.48 (s, 3H, CH3), 7.41 (d, 2H, J ¼ 8.7 Hz, Ar-H), 7.69 (dd, 1H,
J ¼ 8.2 and 8.5 Hz, Ar-H), 7.98 (dd, 1H, J ¼ 8.5 and 8.1 Hz, Ar-H),
8.11 (d, 1H, J ¼ 8.2 Hz, Ar-H), 8.15 (d, 2H, J ¼ 8.7 Hz, Ar-H), 8.42 (d,
2-(4-Bromophenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8b). Yield: 0.329 g (91%), recrystalized from ethanol to afford
faint pink solid; mp 85–888C. IR (KBr): 3018 m, 2214 s, 1640 s cmꢀ1
.
J. Phys. Org. Chem. 2011, 24 203–211
Copyright ß 2010 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/poc

D. P. SHELAR ET AL.
1H, J ¼ 8.1 Hz, Ar-H), 8.92 (s, 2H, Ar-H). 13C NMR (75 MHz CDCl3) d:
24.6, 96.1, 112.3, 121.0, 126.8, 127.6, 128.1, 128.8, 129.1, 129.8,
130.1, 133.6, 136.0, 137.5, 141.2, 146.4, 160.6, 163.7. MS (70 eV)
m/z (%): 295 (89) [Mþ], 280 (56), 199 (39), 183 (32), 147 (34), 134
(36), 119 (100), 91 (42), 77 (22), 65 (20), 44 (18). Anal. Calcd. for
C20H13N3 (295.34): C, 81.35; H, 4.40; N, 14.23%. Found: C, 81.36; H,
4.44; N, 14.25%.
9.46 (s, 1H, Ar-H). 13C NMR (75 MHz DMSO-d6) d: 59.4, 97.0, 114.6,
118.2, 121.0, 122.6, 126.8, 127.3, 128.6, 129.1, 130.0, 135.0, 136.7,
141.5, 146.2, 153.3, 159.7, 161.4. MS (70 eV) m/z (%): 311 (42) [Mþ],
245 (34), 199 (72), 183 (69), 169 (64), 77 (78), 69 (52), 44 (82), 30
(88). Anal. Calcd. for C20H13N3O (311.34): C, 77.17; H, 4.18; N,
13.50%. Found: C, 77.15; H, 4.21; N, 13.52%.
2-(3,5-Bis(trifluoromethyl)phenyl)-7-methoxybenzo[b][1,8]
naphthyridine-3-carbonitrile (8m). Yield: 0.408 g (91%), recrysta-
lized from ethanol to afford dark green solid; mp 220–223 8C. IR
2-(4-Methoxyphenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8h). Yield: 0.289 g (92%), recrystalized from ethanol to afford
yellow solid; mp 120–1238C. IR (KBr): 3031 m, 2209 s, 1649 s,
1027 m cmꢀ1. 1H NMR (300 MHz CDCl3) d: 3.98 (s, 3H, OCH3), 7.12
(d, 2H, J ¼ 9.2 Hz, Ar-H), 7.46 (dd, 1H, J ¼ 8.2 and 8.5 Hz, Ar-H), 7.67
(dd, 1H, J ¼ 8.5 and 8.1 Hz, Ar-H), 7.88 (d, 1H, J ¼ 8.2 Hz, Ar-H), 7.94
(d, 2H, J ¼ 9.2 Hz, Ar-H), 8.12 (d, 1H, J ¼ 8.1 Hz, Ar-H), 9.25 (s, 2H, Ar-
H). MS (70 eV) m/z (%): 311 (84) [Mþ], 296 (52), 280 (49), 268 (58),
134 (28), 121 (27), 107 (32), 77 (27), 60 (32), 44 (88), 32 (66). Anal.
Calcd. for C20H13N3O (311.34): C, 77.17; H, 4.18; N, 13.50%. Found:
C, 77.78; H, 4.20; N, 13.48%.
(KBr): 3024 m, 2215 s, 1642 s, 1032 m cmꢀ1 1H NMR (300 MHz
.
DMSO-d6) d: 4.05 (s, 3H, OCH3), 7.47 (d, 1H, J ¼ 9.3 Hz, Ar-H), 7.53
(s, 1H, Ar-H), 8.27 (d, 1H, J ¼ 9.3 Hz, Ar-H), 8.43 (s, 1H, Ar-H), 8.73 (s,
2H, Ar-H), 9.27 (s, 1H, Ar-H), 9.52 (s, 1H, Ar-H). 13C NMR (75 MHz
DMSO-d6) d: 59.2, 97.4, 112.9, 117.3, 120.4, 121.4, 123.0, 124.5,
128.8, 129.6, 130.6, 131.3, 135.4, 136.4, 141.8, 142.9, 153.2, 158.2,
162.4. MS (70 eV) m/z (%): 447 (93) [Mþ], 404 (44), 378 (38), 224
(52), 202 (55), 165 (31), 44 (41), 31 (82). Anal. Calcd. for
C22H11N3F6O (447.33): C, 59.06; H, 2.46; N, 9.39%. Found: C, 59.09;
H, 2.45; N, 9.42%.
2-(4-Nitrophenyl)benzo[b][1,8] naphthyridine-3-carbonitrile
(8i). Yield: 0.276 g (84%), recrystalized from ethanol to afford
brown solid; mp 105–1088C. IR (KBr): 3033 m, 2239 s, 1647 s,
2-(3,5-Difluorophenyl)-7-methoxybenzo[b][1,8] naphthyridine-3-
carbonitrile (8n). Yield: 0.312 g (89%), recrystalized from ethanol
to afford green solid; mp 241–2438C. IR (KBr): 3027 m, 2210 s,
1
1540 m, 1392 m cmꢀ1. H NMR (300 MHz CDCl3) d: 7.45 (dd, 1H,
1
1644 s, 1047 m cmꢀ1. H NMR (300 MHz DMSO-d6) d: 4.04 (s, 3H,
J ¼ 8.2 and 8.5 Hz, Ar-H), 7.54 (d, 2H, J ¼ 8.8 Hz, Ar-H), 7.77 (dd, 1H,
J ¼ 8.5 and 8.1 Hz, Ar-H), 7.928 (d, 1H, J ¼ 8.2 Hz, Ar-H), 8.10 (d, 1H,
J ¼ 8.1 Hz, Ar-H), 8.56 (d, 2H, J ¼ 8.8 Hz, Ar-H), 9.18 (s, 2H, Ar-H).
Anal. Calcd. for C19H10N4O2 (326.31): C, 69.93; H, 3.06; N, 17.17%.
Found: C, 69.91; H, 3.09; N, 17.20%.
OCH3), 7.48 (d, 1H, J ¼ 9 Hz, Ar-H), 7.54 (s, 1H, Ar-H), 8.28 (d, 1H,
J ¼ 9 Hz, Ar-H), 8.42 (s, 1H, Ar- H), 8.72 (s, 2H, Ar-H), 9.24 (s, 1H, Ar-
H), 9.52 (s, 1H, Ar-H). MS (70 eV) m/z (%): 347 (94) [Mþ], 277 (96),
183 (33), 141 (69), 77 (52), 51 (53), 32 (59). Anal. Calcd. for
C20H11N3F2O (347.32): C, 69.16; H, 3.17; N, 12.10%. Found: C, 69.19;
H, 3.15; N, 12.13%.
2-(4-Chlorophenyl)-7-methoxybenzo[b][1,8] naphthyridine-3-car-
bonitrile (8j). Yield: 0.312 g (90%), recrystalized from ethanol to
afford green needles; mp 271–2738C. IR (KBr): 3025 m, 2222 s,
1636 s, 1593 m, 1035 m cmꢀ1.1H NMR (300 MHz DMSO-d6) d: 4.03
(s, 3H, OCH3), 7.43 (d, 1H, J ¼ 9 Hz, Ar-H), 7.51 (s, 1H, Ar-H), 7.74 (d,
2H, J ¼ 8.1 Hz, Ar- H), 8.08 (d, 2H, J ¼ 8.1 Hz, Ar-H), 8.24 (d, 1H,
J ¼ 9 Hz, Ar-H), 9.21 (s, 1H, Ar H), 9.44 (s, 1H, Ar-H). 13C NMR
(75 MHz DMSO-d6) d: 59.3, 96.2, 112.2, 116.9, 120.2, 122.1, 128.9,
129.4, 129.7, 130.5, 132.5, 135.2, 133.6, 141.8, 147.1, 154.5, 158.7,
161.2. MS (70 eV) m/z (%): 345 (96) [Mþ], 347 (36) [M þ 2], 330 (29),
302 (32), 267 (29), 173 (31), 155 (28), 133 (32), 32 (34). Anal. Calcd.
for C20H12N3ClO (345.78): C, 69.56; H, 3.47; N, 12.17%. Found: C,
69.58; H, 3.48; N, 12.20%.
7-Methoxy-2-(2,5-dimethoxyphenyl)benzo[b][1,8] naphthyridine-3-
carbonitrile (8o). Yield: 0.330 g (88%), recrystalized from ethanol
to afford yellow crystals; mp 254–257 8C. IR (KBr): 3026 m, 2226 s,
1635 s, 1038 m cmꢀ1. 1H NMR (300 MHz DMSO-d6) d: 3.80 (s, 6H, 2
x OCH3), 4.04 (s, 3H, OCH3), 7.13 (d, 1H, J ¼ 9.5 Hz, Ar-H), 7.18 (dd,
1H, J ¼ 2.1 and 9.5 Hz, Ar-H), 7.22 (d, 1H, J ¼ 2.1 Hz, Ar-H), 7.44 (d,
1H, J ¼ 9.5 Hz, Ar-H), 7.52 (s, 1H, Ar-H), 8.24 (d, 1H, J ¼ 9.5 Hz, Ar-H),
9.22 (s, 1H, Ar-H), 9.32 (s, 1H, Ar-H). 13C NMR (75 MHz DMSO-d6) d:
56.2, 57.8, 58.0, 98.7, 112.4, 115.3, 116.0, 116.7, 118.5, 121.7, 122.2,
123.4, 128.1, 130.1, 136.4, 142.3, 143.1, 151.3, 152.2, 153.7, 158.7,
161.3. MS (70 eV) m/z (%): 371 (48) [Mþ], 353 (64), 338 (54), 185
(48), 171 (45), 145 (56), 105 (55), 91 (69), 79 (67), 43 (82), 31 (84).
Anal. Calcd. for C22H17N3O3 (371.39): C, 71.15; H, 4.58; N, 11.32%.
Found: C, 71.18; H, 4.60; N, 11.33%.
2-(4-Bromophenyl)-7-methoxybenzo[b][1,8] naphthyridine-3-car-
bonitrile (8k). Yield: 0.348 g (89%), recrystalized from ethanol to
afford purple solid; mp 275–2778C. IR (KBr): 3010 m, 2213 s, 1642 s,
1
1040 m cmꢀ1. H NMR (300 MHz DMSO-d6) d: 4.04 (s, 3H, OCH3),
7-Methoxy-2-p-tolylbenzo[b][1,8] naphthyridine-3-carbonitrile
(8p). Yield: 0.296 g (91%), recrystalized from ethanol to afford
yellow crystals; mp 222–2258C. IR (KBr): 3035 m, 2226 s, 1625 s,
1026 m cmꢀ1. 1H NMR (300MHz CDCl3) d: 2.47 (s, 3H, CH3), 4.04 (s,
3H, OCH3), 7.33 (d, 1H, J ¼ 9.3 Hz, Ar-H), 7.40 (d, 2H, J ¼ 8.5 Hz, Ar-H),
7.59 (s, 1H, Ar- H), 7.95 (d, 1H, J ¼ 9.3 Hz, Ar-H), 8.15 (d, 2H, J ¼ 8.5 Hz,
Ar-H), 8.75 (s, 1H, Ar-H), 8.83 (s, 1H, Ar-H). 13C NMR (75 MHz CDCl3) d:
24.6, 57.3, 96.5, 111.2, 118.4, 122.3, 123.1, 126.4, 129.1, 129.7, 130.7,
133.0, 134.7, 137.4, 142.5, 143.9, 154.5, 159.4, 160.4. MS (70 eV) m/z
(%): 325 (100) [Mþ], 310 (62), 282 (54), 163 (44), 141 (42), 127 (39), 63
(20), 39 (16). Anal. Calcd. for C21H15N3O (325.36): C, 77.53; H, 4.61; N,
12.92%. Found: C, 77.55; H, 4.60; N, 12.93%.
7.44 (d, 1H, J ¼ 9.3 Hz, Ar-H), 7.52 (s, 1H, Ar-H), 7.88 (d, 2H,
J ¼ 8.1 Hz, Ar- H), 8.01 (d, 2H, J ¼ 8.4 Hz, Ar-H), 8.25 (d, 1H,
J ¼ 9.3 Hz, Ar-H), 9.23 (s, 1H, Ar-H), 9.46 (s, 1H, Ar-H). MS (70 eV) m/
z (%): 389 (36) [Mþ], 391 (35) [M þ 2], 256 (82), 221 (42), 207 (44),
193 (52), 165 (84), 150 (52), 118 (54), 105 (62), 77 (66), 44 (72), 32
(78). Anal. Calcd. for C20H12N3BrO (390.23): C, 61.38; H, 3.06; N,
10.74% Found: C, 61.41; H, 3.09; N, 10.76%.
7-Methoxy-2-phenylbenzo[b][1,8] naphthyridine-3-carbonitrile
(8l). Yield: 0.274 g (88%), recrystalized from ethanol to afford
green solid; mp 239–2428C. IR (KBr): 3020 m, 2210 s, 1644 s,
1
1034 m cmꢀ1. H NMR (300 MHz DMSO-d6) d: 4.04 (s, 3H, OCH3),
7.44 (d, 1H, J ¼ 9 Hz, Ar-H), 7.54 (s, 1H, Ar-H), 7.66 (m, 3H, Ar-H),
7-Methoxy-2-(4-methoxyphenyl)benzo[b][1,8] naphthyridine-3-
carbonitrile (8q). Yield: 0.303 g (88%), recrystalized from ethanol
8.06 (m, 2H, Ar-H), 8.26 (d, 1H, J ¼ 9.3 Hz, Ar-H), 9.24 (s, 1H, Ar-H),
wileyonlinelibrary.com/journal/poc
Copyright ß 2010 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2011, 24 203–211

SYNTHESIS OF NEW SYNTHONS, ORTHOAMINO FORMYL QUINOLINE
to afford yellow solid; mp 235–2378C. IR (KBr): 3021 m, 2218 s,
[3] Z. He, G. H. W. Milburn, A. Danel, A. Puchala, P. Tomasik, D. Rasala, J.
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23–231.
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Lett. 2005, 15, 259–262
1
1639 s, 1036 m cmꢀ1. H NMR (300 MHz DMSO-d6) d: 3.89 (s, 3H,
OCH3), 4.02 (s, 3H, OCH3), 7.21 (d, 2H, J ¼ 8.5 Hz, Ar-H), 7.41 (d, 1H,
J ¼ 8.2 Hz, Ar-H), 7.51 (s, 1H, Ar-H), 8.07 (d, 2H, J ¼ 8.5 Hz, Ar-H),
8.22 (d, 1H, J ¼ 8.2 Hz, Ar-H), 9.18 (s, 1H, Ar-H), 9.38 (s, 1H, Ar-H).
13C NMR (75 MHz DMSO-d6) d: 58.3, 59.4, 97.4, 112.7, 116.0, 117.4,
122.1, 122.4, 127.7, 128.8, 129.1, 130.7, 136.8, 143.2, 144.5, 152.4,
153.3, 158.4, 159.6. MS (70 eV) m/z (%): 341 (78) [Mþ], 326 (42), 298
(41), 255 (52), 135 (46), 107 (38), 77 (32), 44 (86), 32 (82). Anal.
Calcd. for C21H15N3O2 (341.36): C, 73.90; H, 4.39; N, 12.31%. Found:
C, 73.94; H, 4.40; N, 12.33%.
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7-Methoxy-2-(4-nitrophenyl)benzo[b][1,8] naphthyridine-3-carboni-
trile (8r). Yield: 0.265 g (74%), recrystalized from ethanol to afford
yellow solid; mp 224–2278C, IR (KBr): 3020 m, 2211 s, 1642 s,
1559 m, 1367 m, 1045 m cmꢀ1
.
1H NMR (300 MHz DMSO-d6) d:
4.03 (s, 3H, OCH3), 7.32 (d, 2H, J ¼ 8.3 Hz, Ar-H), 7.42 (d, 1H,
J ¼ 8.5 Hz, Ar-H), 7.52 (s, 1H, Ar-H), 8.19 (d, 1H, J ¼ 8.5 Hz, Ar-H),
8.35 (d, 2H, J ¼ 8.3 Hz, Ar-H), 9.20 (s, 1H, Ar-H), 9.42 (s, 1H, Ar-H).
Anal. Calcd. for C20H12N4O3 (356.33): C, 67.41; H, 3.37; N, 15.73%.
Found: C, 67.43; H, 3.35; N, 15.70%.
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Acknowledgements
The authors thank University Grants Commission, New Delhi,
India, for financial support for this research project. They thank
Professor D. D. Dhavale, Department of Chemistry, University of
Pune, India, for his valuable cooperation for the measurement of
1H NMR, 13C NMR, Mass, and Fluorescence. Authors also thank
Dr V. B. Gaikwad, Principal, K. R. T. Arts, B. H. Commerce, and A. M.
Science College, Nashik, Maharashtra, India, for valuable coopera-
tion for the measurement of IR and UV.
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J. Phys. Org. Chem. 2011, 24 203–211
Copyright ß 2010 John Wiley & Sons, Ltd.
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