A novel synthesis of benzo[h]quinolines and study of their fluorescence properties

Article abstract of DOI:10.1002/jhet.5570440646

(Chemical Equation Presented) An elegant synthesis of highly fluorescent benzo[h]quinolines have been accomplished from readily available and highly economical 6-methoxy-1-tetralone in high purity and excellent yield.

Full text of DOI:10.1002/jhet.5570440646

Nov-Dec 2007
1525
A Novel Synthesis of Benzo[h]quinolines and Study of their
Fluorescence Properties
Madhukar N. Jachak*[1], Dhananjay B. Kendre[1], A. B. Avhale[1],
Raghunath B. Toche[1], Ram W. Sabnis [2]
[1] Organic Chemistry Research Center, Department of Chemistry, K. R. T. Arts, B.H. Commerce and
A. M. Science College, Gangapur road, Nashik-422002, (M. S.), India
[2] Ascada Inc, 3947 Thames Avenue Eagan, MN 55123, USA
mn_jachak@hotmail.com
Received December 10, 2006
H3CO
H3CO
O
N
OR
CN
O
NH2
CN
H3CO
Ar
Ar
R = CH3, C2H5, C3H7, C4H9, C5H11
An elegant synthesis of highly fluorescent benzo[h]quinolines have been accomplished from readily
available and highly economical 6-methoxy-1-tetralone in high purity and excellent yield.
J. Heterocyclic Chem., 44, 1525 (2007).
new benzo[h]quinolines were then designed, and all of
INTRODUCTION
them showed very good absorption and emission maxima.
Benzo[h]quinolines have been described in bacteri-
ology [1], chromosomal aberrations [2], fungal bio-
transformation [3], drug metabolizing enzyme induction
[4] and are extensively used in hightechnology electronic
applications such as light emitting device [5], electro-
luminescent device [6], electrolyte batteries [7] and fiber
optics [8]. In contrast to the coumarins ubiquitously used
as fluorescent dyes [9], less attention has been paid to the
quinolines, particularly, benzo[h]quinolines probably
because of their lower extinction coefficients, hypso-
chromic absorption maxima, and more cumbersome
tuning of photophysical properties. However, benzo[h]-
quinolines are more resistant against pH changes (ring
opening) and bleaching caused by chemical or thermal
tackles. Nonetheless quinolines, which absorb at 335 nm
have found applications in fluorescence analysis as well
as in ‘antenna-sensitized’ luminescence [10]. The benzo-
[h]quinolines are highly fluorescent organic compounds
and are used in the dying of specialty papers e.g. security
papers [11]. The strong fluorescence of these compounds
has attracted us to synthesize this particular family of
compounds.
RESULTS AND DISCUSSION
The synthesis of benzo[h]quinolines 4 were achieved
from a highly economical starting material, 6-methoxy-1-
tetralone 1. Compounds 3 were used as a precursor for the
synthesis of compounds 4. Thus the synthesis of
benzo[h]quinolines 4 were achieved by the reaction of
compounds 3 with primary alcohols such as methanol,
ethanol, 1-propanol, 1-butanol or 1-pentanol containing
catalytic amount of potassium hydroxide at 60-120 ºC
furnished desired compounds 4. Completion of reaction
was monitored by thin layer chromatography (TLC). All
products were collected by suction filtration, washed with
methanol and purified by using suitable solvent, affording
the titled compounds 4 in good yield.
It was interesting to note that the ether linkage at
position 2 in benzo[h]quinolines 4 is dependent on the
type of alcohol used at the time of reaction. The
mechanism for the formation of benzo[h]quinolines 4
from compounds 3 is reported in the literature [16].
Isolated yields of benzo[h]quinolines 4 varied widely
from 52 to 90 %. The highest yield 90 % was obtained
when lower alkyl group such as methyl was used while
the lowest yield was obtained when higher alkyl group
such as pentyl was used this may be due to steric
hindrance of the bulky group. Purity of benzo[h]-
quinolines 4 were detected by using HPLC chromatogram
and found to be more than 97 % pure and did not required
any further purification.
We have recently reported facile synthetic routes
towards benzo[h]quinolines, fused quinolines, pyrazolo-
pyridine, pyrazoloquinoline and pyrazolopyridopy-
rimidine derivatives, [12-15]. Here in we are reporting
synthesis and study of photophysical properties of benzo-
[h]quinolines. On the basis of spectral results of the
synthesized benzo[h]quinoline analogues library, sixteen

1526
M. Jachak, D. Kendre, A. Avhale, R. Toche, R. Sabnis
Vol 44
Table 1. The Absorbance and Emission ꢀmax of benzo[h]quinolines (4a-p).
Compd.
Absorbance
max (nm)
Emission
ꢀmax (nm)
R
ꢀ
(4a)
(4b)
(4c)
(4d)
(4e)
(4f)
(4g)
386
390
344
386
402
384
384.5
408
405
426
430
439
453
440
CH3
CH3
CH3
C2H5
C2H5
C3H7
C3H7
(4h)
(4i)
385
384
420
442
C3H7
C3H7
(4j)
(4k)
385
386
446
445
C4H9
C4H9
(4l)
386.5
383.5
440
447
C4H9
C4H9
Figure 1. The Absorption (dotted line) and Emission spectra of
compound (4f).
(4m)
(4n)
(4o)
384.5
383
450
451
C5H11
C5H11
The structures of all the sixteen benzo[h]quinolines
(4p)
384.5
412
C5H11
1
were confirmed by H nmr, 13C nmr, ir and elemental
analysis and found to be in agreement with the structure
proposed. From Table 1, it is evident that the
incorporation of constituents on to the benzo[h]quinoline
nucleus at 2-position has profound influence on the
absorption and emission properties. It was observed that
the substituent at 2-position has less effect on the
absorption wavelength but there is considerable increase
in the emission wavelength as the aliphatic chain of ether
linkage increases. The compound 4f showed good absorp-
tion and emission spectra as shown in the Figure 1.
The reactions reported here represents new synthetic
methods towards synthesis of novel fluorescent benzo-
[h]quinolines, with high yields, simple workup and clean
products.
EXPERIMENTAL
Melting points were determined on a Gallenkamp Melting
Point Apparatus, Mod. MFB-595 in open capillary tubes and are
uncorrected. The H and 13C nmr spectra were recorded on a
Varian XL-300 spectrometer (300 MHz). Chemical shifts are
reported in ppm from internal tetramethylsilane standard and are
given ꢁ-units. The solvents for nmr spectra was duteriochloro-
form unless otherwise stated. Infrared spectra were taken on
Shimadzu IR-408, a Shimadzu FTIR instrument in potassium
bromide pellets unless otherwise stated. UV Spectra were
1
recorded on
a Shimadzu UV-1601 UV–visible Spectro-
photometer. Compounds for UV scan were dissolved in
methanol. Fluorescence spectra were recorded using RF-5301
PC Spectrofluorophotometer. Compounds for fluorescence
Scheme I
O
H3CO
H3CO
N
OR
CN
H3CO
O
NH2
CN
ROH / KOH
EtOH / Piperidine
1
+
Ar
4 a-p
H
CN
CN
Ar
3 a-g
Ar
2 a-g
2
a
b
c
d
e
f
Ar
3
Ar
4
a
b
c
d
e
f
Ar
R
4
i
Ar
R
C6H5
a
b
c
d
e
f
C6H5
p-F-C6H5
CH3
p-Cl-C6H5
C6H5
C3H7
C4H9
C4H9
C4H9
C4H9
C5H11
C5H11
C5H11
m-Cl-C6H5
m-Br-C6H5
p-Cl-C6H5
p-F-C6H5
p-CN-C6H5
C4H9O (Furyl)
p-F-C6H5
p-CN-C6H5
C4H9O (Furyl)
p-F-C6H5
CH3
j
CH3
k
l
m-Cl-C6H5
p-F-C6H5
p-Cl-C6H5
C6H5
C2H5
C2H5
C3H7
C3H7
C3H7
m-Cl-C6H5
m-Br-C6H5
p-Cl-C6H5
p-CN-C6H5
C6H5
m
n
o
p
p-CN-C6H5
C4H9O (Furyl)
g
g
g
h
m-Cl-C6H5
m-Br-C6H5
m-Br-C6H5
p-Cl-C6H5

Nov-Dec 2007
A Novel Synthesis of Benzo[h]quinlines and Study of their Fluorescence Properties
1527
measurements were dissolved in acetonitrile. UV and fluores-
cence scans were recorded from 200 to 500 nm. Elemental
analyses were performed on a Hosli CH-Analyzer and are within
± 0.4 of the theoretical percentage. All reactions were monitored
by thin layer chromatography, carried out on 0.2 mm silica gel
60 F-254 (Merk) plates using UV light (254 and 366 nm) for
detection. Common reagents-grade chemicals are either com-
mercially available and were used without further purification or
prepared by standard literature procedures
2-Arylidenemalononitrile (2) and 2-amino-5,6-dihy-dro-8-
methoxy-4-aryl-4H-benzo[h]chromene-3-carbonitrile (3).
These compounds were synthesized by the literature methods
[17] and [13] respectively
140, 152, 153, 161, 162. Anal. Calcd. for C23H19FN2O2: C,
73.80; H, 5.11; N, 7.48. Found: C, 73.70; H, 5.00; N, 7.25.
4-(4-Cyanophenyl)-2-ethoxy-8-methoxy-5,6-dihydrobenzo-
[h]quinoline-3-carbonitrile (4e). This compound was obtained
as colorless prism (methanol), 2.70 g (71 %), mp 205-206 °C; ir:
(potassium bromide): 2920, 2854, 2218, 2267, 1427, 1161,
1
1011, 877 cm-1. H nmr: (CDCl3) ꢀ 1.51 (t, 3H, CH3), 2.64 (m,
2H, CH2), 280 (m, 2H, CH2), 3.90 (s, 3H, OCH3), 4.63 (q, 2H,
OCH2), 6.67 (d, J = 2.4 Hz, C10H), 6.92 (dd, J = 8.4, 2.3 Hz,
C9H), 7.28 (m, 4H,Ar-H), 8.26 (d, J = 8.3 Hz, C7H); 13C nmr:
(CDCl3) ꢀ 14, 23, 27, 56, 61, 94, 113, 114, 117, 118, 121, 123,
125, 127, 128, 129, 135, 141, 151, 154, 162, 163. Anal. Calcd.
for C24H19N3O2: C, 75.57; H, 5.01; N, 11.01. Found: C, 75.40; H,
4.80; N, 11.19.
8-Methoxy-4-phenyl-2-propoxy-5,6-dihydrobenzo[h]quin-
oline-3-carbonitrile (4f). This compound was obtained as
colorless prism (methanol), 3.25 g (88 %), mp 119-120 °C; ir:
(potassium bromide): 2947, 2938, 2881, 2218, 1554, 1494,
1375, 1151, 849, 792 cm-1; 1H nmr: (CDCl3) ꢀ 1.06 (t, 3H, CH3),
1.87 (m, 2H, CH2), 2.64 (m, 2H, CH2), 2.75 (m, 2H, CH2), 3.85
(s, 3H, OCH3), 4.48 (t, 2H, OCH2), 6.71 (d, J = 2.7 Hz, C10H),
6.87 (dd, J = 8.4, 2.7 Hz, C9H), 7.23 (m, 5H, Ar-H), 8.20 (d, J =
8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 11, 22, 25, 28, 55, 69, 94, 113,
114, 116, 121, 127, 128, 129, 129.2, 129.5, 136, 141, 154, 155,
162, 163. Anal. Calcd. for C24H22N2O2: C, 77.81; H, 5.99; N,
7.56. Found: C, 77.70; H, 5.75; N, 7.61.
General Procedure for Synthesis of 8-methoxy-4-aryl-2-
alcoxy-5,6-dihydrobenzo[h]quinoline-3-carbonitrile (4). A
mixture of (3) (10 mmol) in primary alcohols such as methanol,
ethanol, 1-propanol, 1-butanol, or 1-pentanol (15 ml) containing
catalytic amount of potassium hydroxide (0.5 g) was heated at
60-120 °C for 1-3 h. Completion of reaction was monitored by
thin layer chromatography (TLC). The solid obtained on cooling
was filtered, washed with methanol, dried and recrystallizd from
suitable solvent, furnished the compounds 4 in good yield.
4-(4-Fluorophenyl)-2,8-dimethoxy-5,6-dihydrobenzo[h]-
quinoline-3-carbonitrile (4a). This compound was obtained as
colorless prism (methanol), 3.25 g (90%), mp 198-199 °C; ir:
(potassium bromide): 2925, 2860, 2723, 2221, 1556, 1103, 844,
1
843, 731 cm-1. H nmr: (CDCl3) ꢀ 2.65 (m, 2H, CH2), 2.82 (m,
4-(3-Chlorophenyl)-8-methoxy-2-propoxy-5,6-dihydro-
benzo[h]quinoline-3-carbonitrile (4g). This compound was
obtained as colorless prism (methanol), 3.44 g (85%), mp 130-
131 °C; ir: (potassium bromide): 2968, 2941, 2885, 2222, 1558,
1498, 1379, 1155, 852, 796 cm-1; 1H nmr: (CDCl3) ꢀ 1.04 (t, 3H,
CH3), 1.84 (m, 2H, CH2), 2.61 (m, 2H, CH2), 2.72 (m, 2H, CH2),
3.81 (s, 3H, OCH3), 4.47 (t, 2H, OCH2), 6.71 (d, J = 2.8 Hz,
C10H), 6.85 (dd, J = 8.4, 2.7 Hz, C9H), 7.25 (m, 4H, Ar-H), 8.17
(d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 22, 28, 38, 55, 64,
93, 115, 116, 119, 122, 124, 129, 130, 131, 133, 134, 135, 141,
146, 154, 156, 162, 164. Anal. Calcd. for C24H21ClN2O2: C,
71.19; H, 5.23; N, 6.92. Found: C, 71.03; H, 5.15; N, 6.81.
4-(3-Bromophenyl)-8-methoxy-2-propoxy-5,6-dihydro-
benzo[h]quinoline-3-carbonitrile (4h). This compound was
obtained as colorless prism (methanol), 3.86 g (86 %), mp 141-
142 °C; ir: (potassium bromide): 2961, 2935, 2879, 2216, 1552,
1492, 1373, 1149, 846, 790 cm-1; 1H nmr: (CDCl3) ꢀ 1.05 (t, 3H,
CH3), 1.83 (m, 2H, CH2), 2.64 (m, 2H, CH2), 2.70 (m, 2H, CH2),
3.83 (s, 3H, OCH3), 4.49 (t, 2H, OCH2), 6.70 (d, J = 2.8 Hz,
C10H), 6.81 (dd, J = 8.4, 2.7 Hz, C9H), 7.27 (m, 4H, Ar-H), 8.19
(d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 11, 22, 25, 28, 55, 69,
94, 113, 114, 116, 124, 128, 129, 130, 132, 133, 134, 137, 141,
146, 154, 156, 162, 164. Anal. Calcd. for C24H21BrN2O2: C,
64.15; H, 4.71; N, 6.23. Found: C, 64.00; H, 4.53; N, 6.12.
4-(4-Chlorophenyl)-8-methoxy-2-propoxy-5,6-dihydro-
benzo[h]quinoline-3-carbonitrile (4i) This compound was
obtained as colorless prism (methanol), 3.19 g (71%), mp 135-
136 °C; ir (potassium bromide): 2957, 2917, 2871, 2239, 1554,
1494, 1376, 1152, 849, 794 cm-1; 1H nmr: (CDCl3) ꢀ 1.03 (t, 3H,
CH3), 1.84 (m, 2H, CH2), 2.60 (m, 2H, CH2), 2.73 (m, 2H, CH2),
3.83 (s, 3H, OCH3), 4.46 (t, 2H, OCH2), 6.69 (d, J = 2.8 Hz,
C10H), 6.85 (dd, J = 8.4, 2.7 Hz, C9H), 7.21 (m, 4H, Ar-H), 8.17
(d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 11, 22, 25, 28, 55, 69,
94, 113, 114, 116, 121, 124, 126, 129, 130, 133, 135, 141, 144,
152, 153, 163. Anal. Calcd. for C24H21ClN2O2: C, 71.19; H, 5.23;
N, 6.92. Found: C, 71.30; H, 5.35; N, 6.80.
2H, CH2), 3.91 (s, 3H, OCH3), 4.19 (s, 3H, OCH3), 6.76 (d, J =
2.4 Hz, C10H), 6.91(dd, J = 8.4, 2.4 Hz, C9H), 7.25 (m, 4H, Ar-
H), 8.30 (d, J = 8.3 Hz, C7H); 13C nmr: (CDCl3) ꢀ 24, 28, 54, 55,
93, 112, 113, 115, 121, 126, 127, 128, 128.5, 129, 135, 140, 153,
154, 161, 162. Anal. Calcd. for C22H17FN2O2: C, 73.34; H, 4.75;
N, 7.77. Found: C, 73.22; H, 4.60; N, 7.61.
4-(4-Cyanophenyl)-2,8-dimethoxy-5,6-dihydrobenzo[h]-
quinoline-3-carbonitrile (4b). This compound was obtained as
colorless prism (methanol), 3.11 g (85 %), mp 219-220 °C; ir:
(potassium bromide): 2955, 2840, 2721, 2199, 2221, 1536,
1133, 834, 731 cm-1; 1H nmr: (CDCl3) ꢀ 2.02 (m, 2H, CH2), 2.68
(m, 2H, CH2), 3.81 (s, 3H, OCH3), 4.17 (s, 3H, OCH3), 6.75 (d, J
= 2.4 Hz, C10H), 6.90 (dd, J = 8.4, 2.4 Hz, C9H), 7.27 (m, 4H,
Ar-H), 8.31 (d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 24, 27, 53,
54, 93, 112, 113, 116, 117, 121, 125, 127, 128, 129, 130, 134,
141, 153, 154, 162, 163. Anal. Calcd. for C23H17N3O2: C, 75.19;
H, 4.65; N, 11.43. Found: C, 75.22; H, 4.60; N, 11.51.
4-(2-Furyl)-2,8-dimethoxy-5,6-dihydrobenzo[h]quinoline-
3-carbonitrile (4c). This compound was obtained as colorless
prism (methanol), 2.62 g (79 %), mp 168-169 °C; ir: (potassium
bromide): 2931, 2906, 2840, 2723, 2212, 1534, 1425, 1133, 844,
1
715 cm-1. H nmr: (CDCl3) ꢀ 2.86 (m, 2H, CH2), 3.01 (m, 2H,
CH2), 3.91 (s, 3H, OCH3), 4.18 (s, 3H, OCH3), 6.63 (d, J = 2.4
Hz, C10H), 6.80 (dd, J = 8.4, 2.4 Hz, C9H), 7.10 (m, 3H, Ar-H),
8.26 (d, J = 8.4 Hz, C7H). Anal. Calcd. for C20H16N2O3: C, 72.28;
H, 4.85; N, 8.43. Found: C, 72.15; H, 4.88; N, 8.59.
2-Ethoxy-4-(4-fluorophenyl)-8-methoxy-5,6-dihydrobenzo-
[h]quinoline-3-carbonitrile (4d). This compound was obtained
as colorless prism (methanol), 3.21 g (86%), mp 185-186 °C; ir:
(potassium bromide): 2228, 1606, 1437, 1151, 1028, 866 cm-1.
1H nmr: (CDCl3) ꢀ 1.52 (t, 3H, CH3), 2.61 (m, 2H, CH2), 2.81
(m, 2H, CH2), 3.91 (s, 3H, OCH3), 4.62 (q, 2H, OCH2), 6.67 (d,
J = 2.4 Hz, C10H), 6.91(dd, J = 8.4, 2.4 Hz, C9H), 7.27 (m,
4H,Ar-H), 8.25(d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 24,
28, 55, 62, 93, 112, 113, 115, 121, 122, 126, 127, 128, 130, 137,

1528
M. Jachak, D. Kendre, A. Avhale, R. Toche, R. Sabnis
Vol 44
2-Butoxy-8-methoxy-4-phenyl-5,6-dihydrobenzo[h]quino-
obtained as colorless prism (methanol), 2.76 g (58 %), mp 155-
126 °C; ir: (potassium bromide): 2967, 2941, 2871, 2228, 1559,
1478, 1379, 1159, 846, 782 cm-1; 1H nmr: (CDCl3) ꢀ 0.93 (t, 3H,
CH3), 1.37 (m, 4H, 2CH2), 1.82 (m, 2H, CH2), 2.60 (m, 2H,
CH2), 2.76 (m, 2H, CH2), 3.83 (s, 3H, OCH3), 4.51 (t, 2H,
OCH2), 6.68 (d, J = 2.8 Hz, C10H), 6.84 (dd, J = 8.4, 2.7 Hz,
C9H), 7.28 (m, 4H, Ar-H), 8.19 (d, J = 8.4 Hz, C7H); 13C nmr:
(CDCl3) ꢀ 14, 23, 25, 28, 29, 42, 55, 67, 113, 115, 116, 122,
123, 126, 127, 128, 129, 130, 134, 135, 138, 141, 154, 155, 162,
163. Anal. Calcd. for C26H25BrN2O2: C, 65.41; H, 5.28; N, 5.87.
Found: C, 65.50; H, 5.40; N, 5.84.
4-(4-Chlorophenyl)-8-methoxy-2-pentyloxy-5,6-dihydro-
benzo[h]quinoline-3-carbonitrile (4p). This compound was
obtained as colorless prism (methanol), 2.25 g (52 %), mp 170-
171 °C; ir: (potassium bromide): 2964, 2937, 2881, 2218, 1554,
1494, 1375, 1151, 848, 792 cm-1; 1H nmr: (CDCl3) ꢀ 0.92 (t, 3H,
CH3), 1.38 (m, 4H, 2CH2), 1.83 (m, 2H, CH2), 2.60 (m, 2H,
CH2), 2.76 (m, 2H, CH2), 3.85 (s, 3H, OCH3), 4.52 (t, 2H,
OCH2), 6.71 (d, J = 2.8 Hz, C10H), 6.87 (dd, J = 8.4, 2.7 Hz,
C9H), 7.23 (m, 4H, Ar-H), 8.20 (d, J = 8.4 Hz, C7H); 13C nmr:
(CDCl3) ꢀ 14, 23, 25, 28, 29, 40, 55,
line-3-carbonitrile (4j). This compound was obtained as
colorless prism (methanol), 2.42 g (63 %), mp 118-119 °C; ir:
(potassium bromide): 2925, 2860, 2723, 2221, 1556, 1103, 844,
1
843, 731 cm-1; H nmr: (CDCl3) ꢀ 1.00 (t, 3H, CH3), 1.50 (m,
2H, CH2), 1.85 (m, 2H, CH2), 2.62 (m, 2H, CH2), 2.73 (m, 2H,
CH2), 3.84 (s, 3H, OCH3), 4.52 (t, 2H, OCH2), 6.71 (d, J = 2.8
Hz, C10H), 6.86 (dd, J = 8.4, 2.7 Hz, C9H), 7.21 (m, 5H, Ar-H),
8.21 (d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 19, 25, 28, 31,
55, 67, 113, 114, 116, 121, 123, 126, 127, 128, 129, 130, 131,
134, 139, 141, 154, 162. Anal. Calcd. for C25H24N2O2: C, 78.10;
H, 6.29; N, 7.29. Found: C, 78.00; H, 6.30; N, 7.15.
2-Butoxy-4-(3-chlorophenyl)-8-methoxy-5,6-dihydrobenzo-
[h]quinoline-3-carbonitrile (4k). This compound was obtained as
colorless prism (methanol), 2.72 g (65 %), mp 127-128 °C; ir:
(potassium bromide): 2994, 2957, 2874, 2225, 1554, 1494, 1369,
1
1159, 848, 792 cm-1; H nmr: (CDCl3) ꢀ 1.01 (t, 3H, CH3), 1.53
(m, 2H, CH2), 1.82 (m, 2H, CH2), 2.65 (m, 2H, CH2), 2.73 (m, 2H,
CH2), 3.84 (s, 3H, OCH3), 4.54 (t, 2H, OCH2), 6.70 (d, J = 2.8 Hz,
C10H), 6.84 (dd, J = 8.4, 2.7 Hz, C9H), 7.24 (m, 4H, Ar-H), 8.17
(d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 18, 27, 28, 33, 54, 66,
111, 114, 117, 121, 122, 123, 125, 126, 127, 128, 129, 130, 131,
132, 140, 143, 151, 165. Anal. Calcd. for C25H23ClN2O2: C, 71.68;
H, 5.53; N, 6.69. Found: C, 71.70; H, 5.61; N, 6.55.
67, 113, 114, 116, 121, 123, 124, 125, 127, 128, 129, 133,
135, 138, 151, 159, 163. Anal. Calcd. for C26H25ClN2O2: C,
72.13; H, 5.82; N, 6.47. Found: C, 72.00; H, 5.80; N, 6.30.
2-Butoxy-4-(4-fluorophenyl)-8-methoxy-5,6-dihydrobenzo-
[h]quinoline-3-carbonitrile (4l). This compound was obtained
as colorless prism (methanol), 2.77 g (69%), mp 138-139 °C; ir:
(potassium bromide): 2963, 2937, 2881, 2221, 1553, 1494,
1375, 1151, 849, 792 cm-1; 1H nmr: (CDCl3) ꢀ 1.00 (t, 3H, CH3),
1.51 (m, 2H, CH2), 1.83 (m, 2H, CH2), 2.60 (m, 2H, CH2), 2.76
(m, 2H, CH2), 3.85 (s, 3H, OCH3), 4.53 (t, 2H, OCH2), 6.72 (d, J
= 2.8 Hz, C10H), 6.88 (dd, J = 8.4, 2.7 Hz, C9H), 7.14 (m, 4H,
Ar-H), 8.20 (d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 19, 25,
28, 31, 55, 67, 113, 114, 116, 121, 123, 124, 127, 128, 129, 130,
131, 132, 137, 140, 151, 162.. Anal. Calcd. for C25H23FN2O2: C,
74.61; H, 5.76; N, 6.96. Found: C, 74.70; H, 5.60; N, 6.79.
2-Butoxy-4-(4-chlorophenyl)-8-methoxy-5,6-dihydrobenzo-
[h]quinoline-3-carbonitrile (4m). This compound was obtained
as colorless prism (methanol), 2.55 g (61%), mp 113-114 °C; ir:
(potassium bromide): 2984, 2917, 2855, 2244, 1544, 1435,
1375, 1154, 828, 764 cm-1; 1H nmr: (CDCl3) ꢀ 1.00 (t, 3H, CH3),
1.50 (m, 2H, CH2), 1.80 (m, 2H, CH2), 2.61 (m, 2H, CH2), 2.76
(m, 2H, CH2), 3.81 (s, 3H, OCH3), 4.56 (t, 2H, OCH2), 6.76 (d, J
= 2.8 Hz, C10H), 6.84 (dd, J = 8.4, 2.7 Hz, C9H), 7.23 (m, 4H,
Ar-H), 8.17 (d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 19, 25,
28, 31, 55, 67, 113, 114, 116, 121, 122, 125, 127, 128, 129, 130,
131, 133, 138, 142, 155, 162. Anal. Calcd. for C25H23ClN2O2: C,
71.68; H, 5.53; N, 6.69. Found: C, 71.58; H, 5.41; N, 6.45.
8-Methoxy-2-pentyloxy-4-phenyl-5,6-dihydrobenzo[h]-
quinoline-3-carbonitrile (4n). This compound was obtained as
colorless prism (methanol), 2.39 g (60 %), mp 140-141°C; ir:
(potassium bromide): 2969, 2872, 2219, 1544, 1494, 1376,
Acknowledgement. This research was supported by grants
from University Grants Commission (UGC), New Delhi, India.
Authors thank Prof. D. D. Dhavale, Department of Chemistry,
University of Pune, for his valuable discussion.
REFERENCES AND NOTES
[1] Willumsen, P. A.; Johansen, J. E.; Karlson, U.; Hansen, B.
M. Appl. Microbiol. Biotechnol. 2005, 67, 420.
[2] Serra, J. R.; Thompson, E. D.; Jurs, P. C. Chem. Res. Toxicol,
2003, 16, 153.
[3] Sutherland, J. B.; Cross, E. L.; Heinze, T. M.; Freeman, J. P.;
Moody, J. D. Appl. Microbiol. Biotechno, 2005, 67, 405.
[4] Le, H. T.; Lamb, J. G.; Franklin, M. R. J. Biochem. Toxicol,
1997, 11, 297.
[5] Butler, T.; Patel, N.; Roberts, M.; Baynes, N. PCT Int. Appl.
WO 2006038020, Chem. Abstr. 2006, 144, 378759.
[6] Tanabe, J,; Inoue, T.; Ogawa, H. Jpn. Kokai Tokkyo Koho JP
2005019159, Chem. Abstr. 2005, 142, 165276.
[7] Maruta, J. Jpn. Kokai Tokkyo Koho JP 2000156224, Chem.
Abstr. 2000, 132, 350305.
[8] Hanemann, T.; Boehm, J.; Hausselt, J. PCT Int. Appl.
2004090583, Chem. Abstr. 2004, 141, 357834.
WO
[9] Schiedel, M. S.; Briehn, C. A.; Bauerle, P. Angew. Chem.
Intl. Ed, 2001, 40, 4677.
[10] Li, M.; Selvin, P. R. J. Am. Chem. Soc., 1995, 117, 8132.
[11] Basta, A. H.; Girgis, A. S. Dyes Pigm., 2002, 54, 1.
[12] Toche, R. B.; Jachak, M. N.; Sabnis, R. W.; Kappe, T. J.
Heterocycl. Chem., 1999, 36, 467.
1
1141, 848, 792 cm-1; H nmr: (CDCl3) ꢀ 0.92 (t, 3H, CH3), 1.37
[13] Jachak, M. N.; Kendre, D. B.; Avhale, A. B.; Toche, R. B.;
Medhane, V. J. Org. Prep. Proced. Int., 2006, 38(3), 313.
[14] Jachak, M. N.; Avhale, A. B.; Tantak, C. D.; Toche, R. B.;
Reidlinger, C.; Stadlbauer, W. J. Heterocyclic Chem., 2005, 42, 1311.
[15] Jachak, M. N.; Avhale, A. B.; Medhane, V. J.; Toche, R. B.
J. Heterocyclic Chem., 2006, 43, 1169.
[16] Otto, H. H.; Rinus, O.; Schmelz, H. Monatshefte fur
Chemie., 1979, 110, 115.
[17] Wang, X. S.; Zng, X. S.; Lie, Y. L.; Shi, D. Q.; Tu, S. J.;
Wei, X. Y.; Zong, Z. M. Synth. Commun., 2005, 35, 1915.
(m, 4H, 2CH2), 1.85 (m, 2H, CH2), 2.62 (m, 2H, CH2), 2.75 (m,
2H, CH2), 3.85 (s, 3H, OCH3), 4.52 (t, 2H, OCH2), 6.71 (d, J =
2.8 Hz, C10H), 6.87 (dd, J = 8.4, 2.7 Hz, C9H), 7.23 (m, 5H, Ar-
H), 8.20 (d, J = 8.4 Hz, C7H); 13C nmr: (CDCl3) ꢀ 14, 23, 25, 28,
29, 41, 55, 67, 113, 114, 116, 121, 127, 128, 129, 130, 134, 135,
138, 141, 154, 155, 162, 163. Anal. Calcd. for C26H26N2O2: C,
78.36; H, 6.58; N, 7.03. Found: C, 78.20; H, 6.40; N, 7.14.
4-(3-Bromophenyl)-8-methoxy-2-pentyloxy-5,6-dihydro-
benzo[h]quinoline-3-carbonitrile (4o). This compound was