Ionic Liquid-Promoted Regiospecific Friedlander Annulation: Novel Synthesis of Quinolines and Fused Polycyclic Quinolines

Article abstract of DOI:10.1021/jo035153u

Several room-temperature ionic liquids (ILs) based on 1-butylimidazolium salts with varying anions were synthesized and evaluated for the preparation of biologically active substituted quinolines and fused polycyclic quinolines using the Friedlander heter

Full text of DOI:10.1021/jo035153u

Ion ic Liqu id -P r om oted Regiosp ecific F r ied la n d er An n u la tion :
Novel Syn th esis of Qu in olin es a n d F u sed P olycyclic Qu in olin es
Sanjay S. Palimkar, Shapi A. Siddiqui, Thomas Daniel, Rajgopal. J . Lahoti, and
Kumar V. Srinivasan*
Division of Organic Chemistry, Technology, National Chemical Laboratory, Dr. Homi Bhabha Road,
Pune 411 008, India
kvsri@dalton.ncl.res.in
Received August 6, 2003
Several room-temperature ionic liquids (ILs) based on 1-butylimidazolium salts with varying anions
were synthesized and evaluated for the preparation of biologically active substituted quinolines
and fused polycyclic quinolines using the Friedlander heteroannulation reaction. On screening,
1-butylimidazolium tetrafluoroborate [Hbim]BF4 was found to be the best ionic liquid for the
heteroannulation reaction, and the reasons to this effect are well explained. The reactions proceed
very well under relatively mild conditions without any added catalyst. The IL acts as a promoter
for this regiospecific synthesis and can be recycled. By this green approach, various quinolines
were prepared in excellent yields and purity and well-characterized.
In tr od u ction
combine enhanced electronic, optoelectronic, or nonlinear
optical properties with excellent mechanical properties.7
The best-known method for quinolines and related
polyheterocycles is the Friedlander quinoline synthesis.8
Although it has been known for more than a century, it
is still the most useful method for the preparation of such
a class of compounds. Since 1882, the synthesis of the
quinoline nucleus by the Friedlander procedure has been
extensively explored.9 Hydrochloric acid, sulfuric acid,
p-toluenesulfonic acid and polyphosphoric acid were
widely employed as catalysts.10 In addition, microwave,11
gold(III) compounds,10 diphosgene/ acetonitrile solvent,12
The quinoline nucleus occurs in several natural com-
pounds (cincona alkaloids) and pharmacologically active
substances displaying a broad range of biological activ-
ity.1 The biological activity of quinoline compounds has
been found in the form of antiasthmatic,2 antibacterial,3
antiinflammatory4 and antihypertensive5 properties. In
addition to the medicinal applications, quinolines have
been employed in the study of bioorganic and bioorga-
nometallic processes.6 They are also known for their
formation of conjugated molecules and polymers that
* To whom correspondence should be addressed. Tel: +91-20-588
9089. Fax: +91-20-589 3614.
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Chem. Mater. 1993, 5, 633. (f) J enekhe, S. A.; Lu. L.; Alam, M. M.;
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G., Ed.; J ohn Wiley & Sons: New York, 1982; Vol. 28, Chapter 2. (b)
Friedlander, P. Berichte 1882, 15, 2572. For reviews of quinoline and
naphthyridine syntheses, see: (c) J ones, G. In Comprehensive Hetero-
cyclic Chemistry II; Ramsden, C. A., Ed.; Pergamon Press: Tarrytown,
1996; Vol. 5, Chapter 5.05. (d) J ones, G. In Comprehensive Heterocyclic
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York, 1984; Vol. 2, Chapter 2.08. (e) Lowe, P. A. In Comprehensive
Heterocyclic Chemistry; Boulton, A. J ., McKillop, A., Eds.; Pergamon
Press: New York, 1984; Vol. 2, Chapter 2.11.
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8, 1535. (b) Balasubramanian, M.; Keay, J . G. In Comprehensive
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Press: New York, 1996; Vol. 5, p 245 (c) Yates, F. S. In Comprehensive
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10.1021/jo035153u CCC: $25.00 © 2003 American Chemical Society
Published on Web 10/24/2003
J . Org. Chem. 2003, 68, 9371-9378
9371

Palimkar et al.
ZnCl2/triethylamine13 and more recently a variety of
amines14 were also employed as promoters and catalysts.
Many transition-metal-catalyzed Friedlander-type het-
eroannulation processes have been developed for the
synthesis of quinolines. For example, several ruthenium,
palladium, and iron complexes have been shown to
catalyze the formation of 2,3-disubstiuted quinolines from
nitrobenzene and aldehydes or alcohols in the presence
of CO.15 Also, aniline was shown to undergo N-hetero-
cyclization to generate quinolines with aliphatic alde-
hydes with use of transition-metal complexes.16 Uncat-
alyzed Friedlander synthesis required more drastic
reaction conditions, with temperatures in the range 150-
220 °C. Most of the synthetic protocols for quinolines
reported so far suffer from harsh conditions, poor yields,
prolonged time period, and use of hazardous and often
expensive acid and base catalysts. Moreover, the syn-
thesis of these heterocycles have been usually carried out
in polar solvents such as acetonitrile, THF, DMF, and
DMSO leading to complex isolation and recovery proce-
dures. These processes also generate waste-containing
solvent and catalyst, which have to be recovered, treated,
and disposed of.
In recent years, studies of low waste routes and
reusable reaction media for enhanced selectivity and
energy minimization are the key interests of synthetic
organic chemists world over.17 In this context, in recent
times, the use of room-temperature ionic liquids (ILs) as
“green” solvents in organic synthetic processes has gained
considerable importance due to their solvating ability,
negligible vapor pressure, and easy recyclability.18 They
have the potential to be highly polar yet noncoordinating.
In addition to the above-mentioned salient features of ILs
as reaction media, we have also recently shown that they
can also promote and catalyze organic transformations
of commercial importance under ambient conditions
without the need for any added catalyst or ligand. The
reactions investigated by us are Heck and Suzuki reac-
tions,19 nitration of phenols,20 and bromination of aro-
matics,21 which proceed in significantly enhanced reac-
tion rates, high regioselectivity and excellent isolated
F IGURE 1. Ionic liquids synthesized, characterized, and
screened.
SCHEME 1
yields. In particular, we have recently reported the
heterocyclization reaction of o-phenylenediamines with
both acyclic and cyclic ketones in the IL 1,3-di-n- butyl-
imidazolium bromide ([bbim]Br) to afford 1,5-benzodiaz-
epines in excellent isolated yields in the absence of a
catalyst at ambient temperature.22
Proceeding on the same lines, we chose to evolve an
efficient and ecofriendly process for the preparation of
quinolines and related polyheterocycles using the Fried-
lander heteroannulation protocol in the presence of the
“green” imidazolium ionic liquids as reaction media as
well as promoters in the absence of any added catalyst.
Herein we disclose the successful outcome of this en-
deavor in which o-amino substituted aromatic carbonyls
and ketones/diketones/ketoesters (containing active
methylene groups) afforded excellent yields of the annu-
lation products in the IL, 1-butylimidazolium tetrafluo-
roborate [Hbim]BF4 among several ILs screened.
Resu lts a n d Discu ssion
In view of the emerging importance of the imidazolium-
based ILs as novel reaction media and as a part of our
ongoing investigations of heterocyclization reactions
based on such ILs, we wished to explore their use in the
synthesis of the biologically important quinolines and
related polyheterocycles using the Friedlander reaction
conditions. For this purpose, 2-aminoacetophenone (1a )
and 2-amino-5-chlorobenzophenone (1b) were reacted
with a variety of ketones/ketoesters (2) in the ionic liquid
as shown in Scheme 1.
Two sets of ILs based on N,N-di-n-butylimidazolium
(bbim) and N-butylimidazolium (Hbim) salts with varying
basicity of the anions were synthesized (Figure 1).
They were fully characterized by spectral and elemen-
tal analyses. For the [Hbim] ILs the chemical shifts for
the NH protons were not observable in the 1H NMR
spectra when recorded in CDCl3. However, the NH proton
chemical shifts were observed as broad singlets with
accompanying changes in the chemical shifts of the
(13) J iang, B.; Si, Y, -G. J . Org. Chem. 2002, 67, 9449.
(14) Dormer, P. G.; Eng, K. K.; Farr, R. N.; Humphrey, G. R.;
McWilliams, J . C.; Reider, P. J .; Sager, J . W.; Volante, R. P. J . Org.
Chem. 2003, 68, 467.
(15) (a) Hegedus, L. S. Angew. Chem., Int. Ed. Engl. 1988, 27, 1113.
(b) Watanabe, Y.; Tsuji, Y.; Ohsugi, Y. Tetrahedron Lett. 1981, 22, 2667.
(c) Watanabe, Y.; Suzuki, N.; Tsuji, Y.; Shim, S. C.; Mitsudo, T. Bull.
Chem. Soc. J pn. 1982, 55, 1116. (d) Watanabe, Y.; Tsuji, Y.; Shida, J .
Bull. Chem. Soc. J pn. 1984, 57, 435. (e) Watanabe, Y.; Takatsuki, K.;
Shim, S. C.; Mitsudo, T.; Takegami, Y. Bull. Chem. Soc. J pn. 1978,
51, 3397.
(16) (a)Watanabe, Y.; Tsuji, Y.; Ohsugi, Y.; Shida, J . Bull. Chem.
Soc. J pn. 1983, 56, 2452. (b) Watanabe, Y.; Shim, S. C.; Mitsudo, T.
Bull. Chem. Soc. J pn. 1981, 54, 3460. (c) Larock, R. C.; Hightower, T.
R.; Hasvold, L. A.; Peterson, K. P. J . Org. Chem. 1996, 61, 3584. (d)
Larock, R. C.; Kuo, M.-Y. Tetrahedron Lett. 1991, 32, 569. (e) Beller,
M.; Thiel, O. R.; Trauthwein, H.; Hartung, C. G. Chem. Eur. J . 2000,
6, 2513.
(17) (a) Horvath, I. T.; Rabai, J . Science 1994, 266, 72. (b) Chauvin,
Y., Olivier-Bourbigou, H. CHEMTECH 1995, 25, 26. (c) Seddon, K. R.
J . Chem. Technol. Biotechnol. 1997, 68, 351. (d) Kitazume, T.; Ishizuka,
T.; Takedu, M.; Itoh, K. Green Chem. 1999, 1, 221.
(18) (a) Welton, T. Chem. Rev. 1999, 99, 2071. (b) Wasserscheid P.;
Keim, W. Angew. Chem., Int. Ed. 2000, 39, 3772. (c) Earle, M. J .;
Seddon, K. R. Pure Appl. Chem. 2000, 72, 1391. (d) Gordon, C. M. Appl.
Catal. A: General 2001, 222, 101. (e) Sheldon, R. Chem. Commun.
2001, 2399.
(19) (a) Deshmukh, R. R.; Rajagopal, R.; Srinivasan, K. V. Chem.
Commun. 2001, 1544. (b) Rajagopal, R.; J arikote, D. V.; Srinivasan,
K. V. Chem. Commun. 2002, 616.
(20) (a) Rajagopal, R.; Srinivasan, K. V. Synth. Commun. 2003, 33,
961. (b) Rajagopal, R.; Srinivasan, K. V. Ultrson. Sonochem. 2003, 10,
45.
(21) Rajagopal, R.; J arikote, D. V.; Thomas Daniel; Lahoti, R. J .;
Srinivasan, K. V. Tetrahedron Lett. 2003, 44, 1815.
(22) J arikote, D. V.; Siddiqui, S. A.; Rajagopal, R.; Thomas Daniel;
Lahoti, R. J .; Srinivasan, K. V. Tetrahedron Lett. 2003, 44, 1835.
9372 J . Org. Chem., Vol. 68, No. 24, 2003

Ionic Liquid-Promoted Regiospecific Friedlander Annulation
TABLE 1. Syn th esis of 3c in [bbim ] ILs
30% even after 24 h. At 130 °C, the reflux temperature
of cyclopentanone, the IL decomposed to give a black
charry material. This was further confirmed by running
a thermal gravimetric analysis (TGA), differential ther-
mal gravimetric (DTG) analysis and differential thermal
analysis (DTA) of a pure sample of [Hbim]BF4. The
thermal decomposition started at 152.7 °C, and at 335.3
°C complete weight loss was observed. An endotherm
which was observed at 324.5 °C in DTA may be the result
of the decomposition of the BF4 species into the stable
BF3 and F-. Hence, all subsequent reactions using this
IL were carried out at 100 °C.
IL
pKa of acid of the anion, HX
yielda (%)
[bbim]ClO4
[bbim]Br
[bbim]Cl
[bbim]PF6
[bbim]BF4
-11
-9
37
50
50
70
75
-7
0.5
a
Isolated yield after column chromatography.
TABLE 2. Syn th esis of 3c in [Hbim ] ILs
pKa of acid of
chemical shift
IL
the anion, HX -NH proton δ (ppm) yielda (%)
The IL [Hbim]BF4 was used as a reaction medium and
promoter to generate a variety of quinolines and fused
polycyclic quinolines (3a -v) by the reaction of 2-ami-
noacetophenone (1a ) and 2-amino-5-chlorobenzophenone
(1b) with cyclic/acyclic ketones and keto esters (2),
respectively. The results are recorded in Table 3. All the
reactions proceed to completion at the time indicated in
the Table 3 without any catalyst, and the yield data are
for the isolated products. All the compounds were well
[Hbim]ClO4
[Hbim]Br
[Hbim]Cl
[Hbim]PF6
[Hbim]BF4
-11
-9
11.83
12.17
12.22
12.61
14.59
50
75
73.8
90
96
-7
0.5
a
Isolated yield after column chromatography.
imidazolium protons of the ILs when the 1H NMR spectra
were recorded neat using CDCl3 as external lock. In mass
spectra, all the ILs showed [M - X] as the base peak and
peaks corresponding to the molecular ion were not
observed. The elemental analyses of the ILs were in
conformity with their structures.
The synthesized new ILs were then tested as solvents
and promoters for the typical reaction of o-amino ac-
etophenone (1a ) with cyclopentanone in the absence of
any added catalyst to afford 9-methyl-2, 3-dihydro-1H-
cyclopenta[b]quinoline (3c). The reactions in the various
ILs were carried out at 100 °C for 24 h. The yield data
are recorded in Tables 1 and 2.
The efficacy of the ILs to promote these heterocycliza-
tion reactions was correlated to the basicity of the anions
of the ILs. It was assumed that the nature of the anion
would govern the electrophilicity of the imidazolium
cation, which in turn has a bearing on the acidity of the
ILs. Thus, the yield of 9-methyl-2,3-dihydro-1H-cyclo-
penta[b]quinoline (3c) for the reaction in different ILs
was compared against the pKa values of the correspond-
ing acid of the anion (Tables 1 and 2). The pKa values
were obtained from literature.23 It was observed that with
increasing basicity of the anion (increasing pKa of the
corresponding acid) there is a progressive increase in
yield.
This correlation was more evident in the case of [Hbim]
ILs when the yield of 3c was compared with -NH proton
chemical shifts of the ILs indicative of the Bronsted
acidities of the ILs (Table 2). The yield of 3c increases
progressively with increasing Bronsted acidity of the ILs
as indicated by the increasing downfield shift of the NH
proton.
1
characterized by melting point, IR, H NMR, 13C NMR,
and mass spectral analyses. Their elemental analyses
were in conformity with their structures. In all the cases,
the IL could be recovered almost completely (98%) and
recycled twice with only a very marginal loss in yield (1-
2%) in the second recycle. The respective quinolines and
polyheterocycles (3a -v) were obtained in high regiose-
lectivity and could be isolated in excellent yields in all
cases.
Theoretically, the Friedlander reaction with unsym-
metrical ketones such as ethyl methyl ketone can have
two possible modes of cyclization giving rise to two
regioisomers viz., 2,3-dimethylquinoline and 2-ethylquin-
oline, respectively. Depending upon the catalyst, the
modes of cyclization can change. In the Bronsted acid
catalyzed reaction, 2,3-dimethylquinoline was reported
to be the major product (80%) along with minor amounts
(20%) of the 2-ethylquinoline, whereas under basic condi-
tions, the 2-ethylquinoline was the major product and 2,3-
dimethylquinoline was the minor product.24 To our
surprise, however, the ionic liquid promoted Friedlander
reaction with unsymmetrical ketones such as ethyl
methyl ketone/benzyl acetone respectively afforded re-
giospecifically the 2,3-dialkylquinoline only in excellent
isolated yields (entries 7, 8, 18, and 19). No trace of the
isomeric 2-ethylquinoline could be detected either on TLC
or in 1H NMR of the crude product mixture before
purification by column chromatography. The relatively
mild conditions of the reaction and the absence of
Bronsted/Lewis acid catalyst, both factors promoted by
the use of the IL as the reaction medium may have
contributed to this phenomenon. Additionally, the polar-
ity and the large electrochemical window of the IL may
also have contributed to the observed regiospecificity.
It becomes evident from the foregoing results, the IL
[Hbim]BF4 afforded the best results. Consequently, all
further studies were conducted using this IL as the
reaction medium. The reaction of o-aminoacetophenone
(1a ) with cyclopentanone (2) in [Hbim]BF4 was then
carried out at temperatures below and above 100 °C,
respectively. At 90 °C, the conversion does not go beyond
Con clu sion
It is clear from our results that the ionic liquid
catalyzed reaction of o-amino substituted aromatic car-
bonyls with cyclic and acyclic ketones provides an ef-
ficient new tool for the regiospecific synthesis of quino-
(23) (a) Perrin, D. D. Ionization Constant of Inorganic acids and
bases in aqueous solution, 2nd ed.; Pergamon: Elmsford, NY, 1982.
(b) Bell, R. P. The Proton in Chemistry, 2nd ed.; Cornell University
Press: Ithaca, NY, 1973.
(24) Fennel, E. A. J . Heterocycl. Chem. 1966, 31, 2899.
J . Org. Chem, Vol. 68, No. 24, 2003 9373

Palimkar et al.
TABLE 3. Syn th esis of th e Qu in olin es 3a -v in [Hbim ]BF 4
9374 J . Org. Chem., Vol. 68, No. 24, 2003

Ionic Liquid-Promoted Regiospecific Friedlander Annulation
Ta ble 3 (Con tin u ed )
a
Isolated yield.
J . Org. Chem, Vol. 68, No. 24, 2003 9375

Palimkar et al.
7.0 Hz, 6H, CH3), 1.40 (sept, J ) 7.6 Hz, 4H, CH3CH2(CH2)2N),
1.97 (pent, J ) 7.5 Hz, 4H, NCH2CH2), 4.41 (t, J ) 7.0 Hz,
4H, NCH2), 7.87 (s, 2H, NCHCHN), 9.20 (s, 1H, NCHN); 13C
NMR δ ) 12.9, 18.9, 31.6, 49.3, 122.2, 135.2; MS m/z 181
(M - X, 100), 165 (15), 151 (12), 138 (61), 124 (40), 107 (33),
97 (65), 81 (62), 68 (16), 57 (42). Anal. Calcd for C11H21N2BF4
(268): C, 49.25; H, 7.83; N, 10.44. Found: C, 49; H, 7.71; N,
10.21.
lines and fused polycyclic quinolines under relatively mild
conditions. In conclusion, we have developed a green
approach to Friedlander synthesis of quinolines that
requires neither harsh conditions nor the use of hazard-
ous acids or bases. The solvent IL can be recovered and
reused twice without any loss of activity. Several new
ILs were synthesized, characterized and screened for this
heterocyclization reaction. The efficacy of the ILs for the
heterocyclization reaction has been correlated to the
acidity of the ILs in terms of basicity of the anions and
1H NMR chemical shifts. The moderate reaction condi-
tions, absence of a catalyst and recyclability of the
nonvolatile IL makes this an environment friendly
methodology amenable for scale-up.
Similarly, other ionic liquids such as [bbim]PF6 and [bbim]-
ClO4 were prepared as above using the corresponding acid of
the anion.
1,3-Di-n -bu tylim id a zoliu m h exa flu or p h osp h a te [bbim ]
P F 6: viscous oil (11.17 g; yield 92%); IR (KBr) ν ) 3603, 3146,
2936, 1565, 1466, 1166, 1091, 754, 623 cm-1 1H NMR δ )
;
0.89-0.92 (t, J ) 7.0 Hz, 6H, CH3), 1.29-1.34 (sept, J ) 7.6
Hz, 4H, CH3CH2(CH2)2N), 1.81-1.84 (pent, J ) 7.5 Hz, 4H,
NCH2CH2), 4.15-4.18 (t, J ) 7.0 Hz, 4H, NCH2), 7.35 (s, 2H,
NCHCHN), 8.86 (s, 1H, NCHN); 13C NMR δ ) 13.1, 19.2, 31.8,
49.8, 122.4, 135.2; MS m/z 181 (M - X, 100), 165 (15), 151
(12), 138 (61), 124 (40), 107 (33), 97 (65), 81 (62), 68 (16), 57
(42). Anal. Calcd for C11H21N2PF6 (325): C, 40.61; H, 6.46; N,
8.61. Found: C, 40.56; H, 6.31; N, 8.52.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. For Hbim IL series, 1H NMR
was taken neat using CDCl3 as an external lock and for bbim
series solutions in CDCl3 were used for the spectra. Melting
points were taken in open capillary and are uncorrected.
Column chromatography was performed using silica gel (60-
120 mesh size), and TLC was carried out using aluminum
sheets precoated with silica gel 60F254. All solvents and
chemicals used were reagent grade procured commercially and
used without further purification.
P r ep a r a tion of Differ en t Ion ic Liqu id s. 1,3-Di-n -bu -
tylim id a zoliu m Br om id e [bbim ]Br . A mixture of 1-n-
butylimidazole (12.4 g, 0.1 mol) and n-butyl bromide (15.0 g,
0.11 mol) was heated with stirring at 70 °C for 4 h. Excess
n-butyl bromide was distilled off at 80 °C under reduced
pressure (10 mm Hg) over 2 h leaving behind the product
[bbim]Br: colorless liquid (25.06 g; yield 96%); IR (KBr) ν )
3401, 3067, 2874, 1635, 1563, 1465, 1167, 753 cm-1; 1H NMR
δ ) 0.74 (t, J ) 7.0 Hz, 6H, CH3), 1.13 (sept, J ) 7.6 Hz, 4H,
CH3CH2(CH2)2N), 1.69 (pent, J ) 7.5 Hz, 4H, NCH2CH2), 4.13
(t, J ) 7.0 Hz, 4H, NCH2), 7.47 (s, 2H, NCHCHN), 10.08 (s,
1H, NCHN); 13C NMR δ ) 12.4, 18.4, 31.1, 48.7, 121.6, 135.6;
MS m/z 181 (M - X, 31), 165 (3), 151 (6), 138 (37), 124 (53),
109 (8), 97 (100), 81 (87), 68 (21), 57 (29). Anal. Calcd for
C11H21N2Br (261): C, 50.57; H, 8.05; N, 10.73. Found: C, 50.24;
H, 7.91; N, 10.54.
1,3-Di-n -b u t ylim id a zoliu m p er ch lor a t e [b b im ] ClO4:
viscous oil (10.55 g; yield 98%); IR (KBr) ν ) 3603, 3146, 2936,
1565, 1466, 1166, 1091, 754, 623 cm-1 1H NMR δ ) 0.88-
;
0.91 (t, J ) 7 Hz, 6H, CH3), 1.29-1.36 (sept, J ) 7.6 Hz, 4H,
CH3CH2(CH2)2N), 1.80-1.85 (pent, J ) 7.5 Hz, 4H, NCH2CH2),
4.16-4.21 (t, J ) 7 Hz, 4H, NCH2), 7.4 (s, 2H, NCHCHN),
9.02 (s, 1H, NCHN); 13C NMR δ ) 13.1, 19.1, 31.8, 49.6, 122.5,
135.3; MS m/z 181 (M - X, 100), 165 (15), 151 (12), 138 (61),
124 (40), 107 (33), 97 (65), 81 (62), 68 (16), 57 (42). Anal. Calcd
for C11H21N2ClO4 (281): C, 46.97; H, 7.47; N, 9.96. Found: C,
46.74; H, 7.21; N, 9.82.
1-Bu tylim idazoliu m Tetr aflu or obor ate [Hbim ]BF 4. Tet-
rafluoroboric acid (8.7 g, 0.1 mol) as 40% aqueous solution was
added slowly over a period of 30 min to 1-butylimidazole (12.4
g, 0.1 mol) at 0 °C under stirring. The reaction mixture was
stirred for an additional period of 2 h at the same temperature.
Water was removed from the reaction mixture by subjecting
it to evaporation for 4 h at 80 °C under reduced pressure (10
mm Hg) to give the product [Hbim]BF4: viscous oil (19.97 g;
yield 96%); IR (KBr) ν ) 3607, 3153, 2876, 1580, 1466, 894,
762 cm-1; 1H NMR δ ) 0.56 (s, 3H, CH3), 0.95 (s, 2H, CH3CH2-
(CH2)2N), 1.47 (s, 2H, NCH2CH2), 3.87 (s, 2H, NCH2), 7.12 (s,
2H, NCHCHN), 8.16 (s, 1H, NCHN), 14.59 (brs, 1H, NH); 13
C
1,3-Di-n -bu tylim id a zoliu m Ch lor id e [bbim ]Cl. A mix-
ture of 1-n-butylimidazole (12.4 g, 0.1 mol) and n-butyl chloride
(10.17 g, 0.11 mol) was refluxed in toluene for 8 h. Toluene
and excess n-butyl chloride were distilled off at 80 °C under
reduced pressure (10 mm Hg) over 2 h leaving behind the
product [bbim]Cl: viscous oil (20.61 g; yield 95%); IR (KBr)
NMR δ ) 13.1, 19.2, 32.1, 48.5, 120.9, 122.8, 135.2; MS: m/z
124 (M - X, 26), 109 (3), 97 (92), 81 (100), 68 (26), 55 (56).
Anal. Calcd for C7H13N2BF4 (211): C, 39.81; H, 6.16; N, 13.27.
Found: C, 39.81; H, 6.05; N, 13,18.
Similarly, the other ILs, viz. [Hbim]Br, [Hbim]Cl, [Hbim]-
PF6, and [Hbim]ClO4, were prepared as above using the
corresponding acid of the anion.
1
ν ) 3401, 3067, 2874, 1635, 1563, 1465, 1167, 753 cm-1; H
NMR δ ) 0.80 (t, J ) 7.0 Hz, 6H, CH3), 1.24 (sept, J ) 7.6 Hz,
4H, CH3CH2(CH2)2N), 1.72 (pent, J ) 7.5 Hz, 4H, NCH2CH2),
4.22 (t, J ) 7.0 Hz, 4H, NCH2), 7.48 (s, 2H, NCHCHN), 10.38
(s, 1H, NCHN); 13C NMR δ ) 13.1, 19.1, 31.9, 49.3, 122.2,
136.9; MS m/z 181 (M - X, 31), 165 (3), 151 (6), 138 (37), 124
(53), 109 (8), 97 (100), 81 (87), 68 (21), 57 (29). Anal. Calcd for
1-Bu tylim id a zoliu m br om id e [Hbim ]Br : viscous oil
(16.20 g; yield 98%); IR (KBr) ν ) 3607, 3153, 2876, 1580, 1466,
894, 762 cm-1 1H NMR δ ) 0.21 (s, 3H, CH3), 0.64 (s, 2H,
;
CH3CH2(CH2)2N), 1.31 (s, 2H, NCH2CH2), 4.03 (s, 2H, NCH2),
7.39 (s, 1H, NCHCHN), 7.64 (s, 1H, NHCHN), 9.18 (s, 1H,
NCHN), 12.22 (brs, 1H, NH); 13C NMR δ ) 13.1, 19.1, 32.4,
47.3, 120, 124.7, 136.1; MS m/z 124 (M - X, 26), 109 (3), 97
(92), 81 (100), 68 (26), 55 (56). Anal. Calcd for C7H13N2Br
(206): C, 40.97; H, 6.34; N, 13.65. Found: C, 40.54; H, 6.11;
N, 13,18.
C
11H21N2Cl (217): C, 60.82; H, 9.67; N, 12.9. Found: C, 60.64;
H, 9.71; N, 12.81.
1,3-Di-n -bu tylim id a zoliu m Tetr a flu or obor a te [bbim ]-
BF 4. To a solution of 1,3-di-n-butylimidazolium bromide
([bbim]Br) (10 g, 0.1 mol) in water (50 mL) was added a
solution of sodium tetrafluoroborate (5.11 g, 1.2 mol) in water
(25 mL), and the mixture was stirred at 30 °C for 5 h. The
ionic liquid [bbim]BF4 separated out as an immiscible layer.
The mixture was extracted with dichloromethane (3 × 30 mL).
The combined DCM (dichloromethane) layer, which was
separated, was washed with water and brine and dried over
anhydrous sodium sulfate. The solvent DCM was distilled off
under reduced pressure leaving behind the pure IL [bbim]BF4:
viscous oil (8.72 g; yield 86%); IR (KBr) ν ) 3401, 3067, 2874,
1-Bu t ylim id a zoliu m ch lor id e [Hbim ]Cl: viscous oil
(12.72 g; yield 98%); IR (KBr) ν ) 3607, 3153, 2876, 1580, 1466,
894, 762 cm-1 1H NMR δ ) 0.48 (s, 3H, CH3), 0.88 (s, 2H,
;
CH3CH2 (CH2)2N), 1.42 (s, 2H, NCH2CH2), 4 (s, 2H, NCH2),
7.11 (s, 1H, NCHCHN), 7.47 (s, 1H, NHCHN), 8.69 (s, 1H,
NCHN), 12.17 (brs, 1H, NH); 13C NMR δ ) 11.7, 17.7, 30.9,
45.7, 118.3, 123.7, 134.7; MS m/z 124 (M - X, 26), 109 (3), 97
(92), 81 (100), 68 (26), 55 (56). Anal. Calcd for C7H13N2Cl
(161): C, 52.17; H, 8.07; N, 17.39. Found: C, 52.08; H, 8; N,
17.28.
1
1635, 1563, 1465, 1167, 753 cm-1; H NMR δ ) 0.96 (t, J )
9376 J . Org. Chem., Vol. 68, No. 24, 2003

Ionic Liquid-Promoted Regiospecific Friedlander Annulation
1-Bu tylim id a zoliu m h exa flou or p h osp h a te [Hbim ]P F 6:
157.9; MS m/z 198 (M+, 87), 125 (100). Anal. Calcd for C14H15
N
viscous oil (21.25 g; yield 98%); IR (KBr) ν ) 3607, 3153, 2876,
(198): C, 85.24; H, 7.66; N, 7.10. Found: C, 85.12; H, 6.58; N,
7.05.
1580, 1466, 894, 762 cm-1 1H NMR δ ) 0.42 (s, 3H, CH3),
;
0.84 (s, 2H, CH3CH2(CH2)2N), 1.43 (s, 2H, NCH2CH2), 3.96 (s,
2H, NCH2), 7.18 (s, 2H, NCHCHN), 8.56 (s, 1H, NCHN), 12.61
(brs, 1H, NH); 13C NMR δ ) 12.6, 18.5, 31.1, 48.7, 119.5, 121.2,
133.7; MS m/z 124 (M - X, 26), 109 (3), 97 (92), 81 (100), 68
(26), 55 (56). Anal. Calcd for C7H13N2PF6 (269): C, 31.26; H,
4.83; N, 10.40. Found: C, 31.10; H, 4.71; N, 10.18.
11-Meth yl-7,8,9,10-tetr a h yd r o-6H-cycloh ep ta [b]qu in o-
lin e (3e): mp 108 °C; IR (KBr) ν ) 3073, 2928, 1645, 1215,
1
755 cm-1; H NMR δ ) 1.61-1.79 (m, 6H), 2.54 (s, 3H), 2.90
(t, J ) 6.4 Hz, 2H), 3.12 (t, J ) 6.9 Hz, 2H), 7.39-7.90 (m,
4H); 13C NMR δ ) 14.3, 27.1, 28, 31.9, 40.1, 124, 125.7, 128.1,
129.3, 134.4, 139.3, 145.8, 164.5; MS m/z 212 (M+, 100), 158
(2). Anal. Calcd for C15H17N (212): C, 85.26; H, 8.11; N, 6.63.
Found: C, 85.12; H, 8.15; N, 6.55.
1-Bu tylim id a zoliu m p er ch lor a te [Hbim ]ClO4: viscous
oil (17.78 g; yield 98%); IR (KBr) ν ) 3607, 3153, 2876, 1580,
1466, 894, 762 cm-1; 1H NMR δ ) 0.71 (t, J ) 7.0 Hz, 3H,
CH3); 1.17 (sept, J ) 7.6 Hz, 2H, CH3CH2(CH2)2N), 1.73 (pent,
J ) 7.5 Hz, 2H, NCH2CH2), 4.16 (t, J ) 7.0 Hz, 2H, NCH2),
7.15 (s, 1H, NCHCHN), 7.42 (s, 1H, NHCHN), 8.57 (s, 1H,
NCHN), 11.83 (brs, 1H, NH); 13C NMR δ ) 12.6, 18.5, 31.1,
48.7, 119.5, 121.2, 133.7; MS m/z 124 (M - X, 26), 109 (3), 97
(92), 81 (100), 68 (26), 55 (56). Anal. Calcd for C7H13N2ClO4
(225): C, 37.33; H, 5.77; N, 12.44. Found: C, 37.10; H, 5.61;
N, 12.18.
7-Meth yl-5,6-d ih yd r oben zo[c]a cr id in e (3f): mp 112 °C;
IR (KBr) ν ) 3070, 3018, 2946, 2842, 1680, 1582, 1499, 1215,
1
758 cm-1; H NMR δ ) 2.56 (s, 3H), 2.90 (t, J ) 7 Hz, 2H),
3.03 (t, J ) 6.8 Hz, 2H), 7.17-8.49 (m, 8H); 13C NMR δ ) 13.6,
25, 27.8, 123.3, 125.2, 126.1, 126.9, 127.4, 128, 128.9, 129.1,
129.9, 133.1, 134.9, 138.8, 139.4, 146.6, 152.3; MS m/z 246 (M+,
100), 212 (3), 125 (31). Anal. Calcd for C18H15N (246): C, 88.13;
H, 6.16; N, 5.71. Found: C, 88.12; H, 6.09; N, 5.63.
2,3,4-Tr im eth ylqu in olin e (3g): mp 110 °C; IR (KBr) ν )
1
3070, 2927, 1523, 1497, 1373, 1216, 753 cm-1; H NMR δ )
P r ep a r a tion of Qu in olin es a n d P olyh eter ocycles. Gen -
er a l P r oced u r e for 3a -v. A mixture of o-amino-substituted
ketones (1a or 1b, 1 mol), ketone (2, 1 mol), and [Hbim]BF4 (1
mol) was heated at 100 °C with good stirring for the appropri-
ate time mentioned in Table 2. The completion of reaction was
monitored by TLC using eluent 20% ethyl acetate in petroleum
ether. After completion of the reaction, the reaction mixture
was diluted with water (25 mL). The solid quinoline product
which separated out was filtered, washed with water, and
dried. The quinolines which are liquids were extracted with
ethyl acetate (2 × 10 mL) and dried over sodium sulfate, and
the solvent was evaporated under reduced pressure to furnish
crude product. The crude products, thus isolated, were pure
(single spot on TLC). They were subjected to further purifica-
tion by chromatography through a column of silica gel using
20% EtOAc in petroleum ether as eluent to yield the desired
substituted quinolines in an average 85-96% and were fully
characterized.
2.41 (s, 3H), 2.6 (s, 3H), 2.71 (s, 3H), 7.46-7.99 (m, 4H); 13C
NMR δ ) 14.2, 15.6, 24.6, 123.3, 125.2, 127.7, 129.1, 140.3,
145.8, 158.2; MS m/z 172 (M+, 100), 158 (24), 60 (4). Anal.
Calcd for C12H13N (172): C, 84.17; H, 7.65; N, 8.18. Found:
C, 84.12; H, 7.59; N, 8.13.
2,4-Dim eth yl-3-ben zylqu in olin e (3h ): mp 143 °C; IR
(KBr) ν ) 3064, 3017, 2932, 1604, 1586, 1494, 1216, 755 cm-1
;
1H NMR δ ) 2.53 (s, 3H), 2.57 (s, 3H), 4.2 (s, 2H), 6.93-7.95
(m, 9H); 13C NMR δ ) 14.3, 24.3, 35, 123.6, 125.4, 126, 127.1,
127.7, 128.4, 128.7, 129.1, 129.7, 138.7, 141.8, 146.2, 158.7;
MS m/z 262 (M+, 3), 248 (100), 125 (27). Anal. Calcd for
C
18H17N (262): C, 87.41; H, 6.93; N, 5.66. Found: C, 87.12;
H, 6.89; N, 5.63.
4-Meth yl-2-p h en ylqu in olin e (3i): oil; IR (KBr) ν ) 3061,
1
2958, 1684, 1265, 770 cm-1; H NMR δ ) 2.51 (s, 3H), 7.35-
8.08 (m, 10H); 13C NMR δ ) 18.8, 119.6, 123.6, 126, 127.5,
128, 128.3, 128.5, 128.7, 129.2, 133, 137.2, 139.8, 144.7, 148.2,
156.9; MS m/z 220 (M+, 100), 125 (19). Anal. Calcd for C16H13
N
The aqueous layer consisting of the IL was subjected to
distillation (80 °C at 10 mm Hg) for 2 h to remove water,
leaving behind the IL [Hbim]BF4 (recovery 98%), which was
recycled.
(220): C, 87.64; H, 5.98; N, 6.39. Found: C, 87.12; H, 5.89; N,
6.33.
2-(4-Ch lor op h en yl)-4-m eth ylqu in olin e (3j): mp 75 °C;
IR (KBr) ν ) 3019, 1685, 1597, 1215, 757 cm-1; 1H NMR δ )
2.5 (s, 3H), 7.3-8.08 (m, 9H); 13C NMR δ ) 18.7, 119, 123.4,
126, 127.1, 128.6, 129.5, 130.1, 135.2, 138, 139.3, 146, 147.9,
155.4; MS m/z 254 (M+, 86), 248 (8), 198 (100), 181 (6), 125
(50), 110 (13). Anal. Calcd for C16H12ClN (245): C, 75.74; H,
4.77; N, 5.52. Found: C, 75.68; H, 4.71; N, 5.48.
2,4-Dim eth ylqu in olin e-3-ca r boxylic a cid eth yl ester
(3a ): oil; IR (KBr) ν ) 3070, 2930, 2873, 1725, 1614, 1589,
1214, 1082, 578 cm-1; 1H NMR δ ) 1.8 (t, J ) 7 Hz, 3H), 3 (s,
3H), 3.1 (s, 3H), 4.8 (q, J ) 7 Hz, 2H), 7.8-8.4 (m, 4H); 13C
NMR δ ) 14.1, 15.4, 23.6, 61.4, 123.8, 125.7, 126.1, 127.9,
129.2, 129.8, 141.2, 147, 154.2, 168.9; MS m/z 230 (M+, 100),
158 (18). Anal. Calcd for C14H15NO2 (230): C, 73.34; H, 6.59;
N, 6.11. Found: C, 73.12; H, 6.48; N, 6.05.
2-(4-Br om op h en yl)-4-m eth ylqu in olin e (3k ): oil; IR (KBr)
1
ν ) 3019, 1685, 1597, 1215, 757 cm-1; H NMR δ ) 2.24 (s,
3H), 7.21-7.85 (m, 9H); 13C NMR δ ) 18.7, 118.9, 123.6, 126,
126.3 127.1, 128.8, 129.6, 130.1, 131.6, 135.7, 138.3, 144.8,
147.9, 155.3; MS m/z 298 (M+, 100), 220 (4), 181 (6), 125 (42).
Anal. Calcd for C16H12BrN (298): C, 64.45; H, 4.06; N, 4.70.
Found: C, 64.39; H, 4.10; N, 4.66.
1-(2,4-Dim eth ylqu in olin -3-yl)eth an on e (3b): oil; IR (KBr)
1
ν ) 3068, 2959, 1703, 1614, 1585, 1208, 758 cm-1; H NMR
δ ) 2.57 (s, 3H), 2.58 (s, 3H), 2.62 (s, 3H), 7.53-8.01 (m, 4H);
13C NMR δ ) 15, 23.3, 32.4, 123.5, 126.2, 129, 129.6, 135.6,
138.4, 146.7, 152.4, 206.3; MS m/z 200 (M+, 100), 158 (11), 125
(4). Anal. Calcd for C13H13NO (200): C, 78.38; H, 6.58; N, 7.03.
Found: C, 78.12; H, 6.48; N, 6.85.
6-Ch lor o-2-m eth yl-4-p h en yl-u in olin e-3-ca r boxylic a cid
eth yl ester (3l): mp 108 °C; IR (KBr) ν ) 3064, 2983, 1725,
1
1605, 1224, 907, 732 cm-1; H NMR δ ) 0.92-0.95 (t, J ) 7
9-Me t h y l-2,3-d ih y d r o -1H -c y c lo p e n t a [b ]q u in o lin e
Hz, 3H), 2.73 (s, 3H), 4.03-4.07 (q, J ) 7 Hz 2H), 7.32-8 (m,
8H); 13C NMR δ ) 13.5, 23.6, 61.4, 125.1, 125.9, 128.4, 128.7,
129.2, 130.5, 131, 132.3, 135, 145.3, 146, 154, 168; MS: m/z
325 (M+, 77), 296 (10), 280 (100), 252 (35), 217 (63), 189 (22),
176 (53), 149 (53), 123 (13), 109 (19), 88 (19), 71 (19), 57 (33).
Anal. Calcd for C20H19ClNO2(325): C, 70.05; H, 4.95; N, 4.30.
Found: C, 70.09; H, 4.90; N, 4.36.
(3c): mp 60 °C; IR (KBr) ν ) 3065, 2957, 1613, 908, 751 cm-1
;
1H NMR δ ) 2.2 (m, 2H), 2.5 (s, 3H), 3 (t, J ) 7.5 Hz, 2H), 3.3
(t, J ) 6.9 Hz 2H), 7.46-8 (m, 4H); 13C NMR δ ) 14.6, 22.7,
29.4, 34.8, 123.1, 125, 126.9, 127.8, 128.9, 133.7, 137.8, 147.2,
166.7; MS m/z 183 (M+, 40), 168 (100), 154 (5), 140 (5), 127
(10), 115 (13), 102 (5), 90 (18), 77 (91), 63 (9), 57 (3). Anal.
Calcd for C13H13N (183): C, 85.21; H, 7.15; N, 7.64. Found:
C, 85.12; H, 6.98; N, 7.55.
1-(6-C h lo r o -2-m e t h y l-4-p h e n y lq u in o lin -3-y l)e t h a -
n on e (3m ): mp 151 °C; IR (KBr) ν ) 3029, 2960, 1701, 1606,
1
1567, 1481, 909, 692 cm-1; H NMR δ ) 1.98 (s, 3H), 2.66 (s,
9-Meth yl-1,2,3,4-tetr a h yd r oa cr id in e (3d ): mp 78 °C; IR
1
(KBr) ν ) 3068, 2935, 1614, 1581, 1350, 755 cm-1; H NMR
3H), 7.32-7.98 (m, 8H); 13C NMR δ ) 23.6, 31.6, 124.7, 125.8,
128.8, 129.1, 129.8, 130.8, 132.3, 134.5, 135.4, 142.9, 145.8,
153.8, 204.9; MS m/z 295 (M+, 41), 280 (100), 252 (29), 217
(48), 189 (15), 176 (47), 149 (27), 109 (11), 94 (9), 75 (7). Anal.
δ ) 1.73 (m, 4H), 2.25 (s, 3H), 2.61 (t, J ) 7.6 Hz, 2H), 2.94 (t,
J ) 7.6 Hz, 2H), 7.24-7.83 (m, 4H); 13C NMR δ ) 12.9, 22.3,
22.7, 26.5, 33.9, 122.8, 124.7, 126.4, 127.6, 128.4, 140.7, 145.4,
J . Org. Chem, Vol. 68, No. 24, 2003 9377

Palimkar et al.
Calcd for C18H14ClNO (295): C, 73.10; H, 4.77; N, 4.74.
Found: C, 73.0; H, 4.60; N, 4.66.
3-Ben zyl-6-ch lor o-2-m eth yl-4-ph en ylqu in olin e (3s): mp
136 °C; IR (KBr) ν ) 3063, 2957, 1603, 1482, 1215, 756 cm-1
;
1H NMR δ ) 2.51 (s, 3H), 3.92 (s, 2H), 6.81-7.93 (m, 13H);
13C NMR δ ) 24.3, 36, 125.1, 126, 127.8, 128.2, 128.4, 129,
129.5, 130.1, 131.4, 136.2, 139.4, 144.9, 146.9, 159.7; MS m/z
344 (M+, 100), 254 (16), 125 (4). Anal. Calcd for C23H18ClN
(344): C, 80.34; H, 5.28; N, 4.07. Found: C, 80.25; H, 5.18;
N, 4.
7-Ch lor o-9-p h en yl-2,3-d ih yd r o-1H-cyclop en ta [b]qu in -
olin e (3n ): mp 105 °C; IR (KBr) ν ) 3060, 2958, 1606, 1487,
828, 715 cm-1; 1H NMR δ ) 2.12 (m, 2H), 2.87 (t, J ) 7.2 Hz,
2H), 3.19 (t, J ) 7 Hz, 2H), 7.3-7.98 (m, 8H); 13C NMR δ )
23.3, 30.2, 35, 124.4, 126.9, 128.2, 128.6, 129, 130.3, 131.2,
134.3, 135.9, 141.8, 146.3, 167.7; MS m/z 279 (M+, 80), 244
(100), 202 (16), 167 (19), 121 (52), 114 (17), 94 (10), 87 (5), 75
(6), 63 (5). Anal. Calcd for C18H14ClN (279): C, 77.28; H, 5.04;
N, 5.01. Found: C, 77.19; H, 4.94; N, 4.86.
7-Ch lor o-9-p h en yl-1,2,3,4-tetr a h yd r oa cr id in e (3o): mp
163 °C; IR (KBr) ν ) 3060, 2944, 1604, 1572, 1481, 1215, 703
cm-1; 1H NMR δ ) 1.55 (m, 2H), 1.59 (m, 2H), 2.56 (t, J ) 6.5
Hz, 2H), 3.3 (t, J ) 7 Hz, 2H), 7.2-8 (m, 8H); 13C NMR δ )
23, 28.2, 34.3, 124.6, 127.5, 128.2, 128.9, 129.1, 129.3, 129.5,
130.2, 131.3, 136.5, 144.8, 145.8, 159.6; MS m/z 293 (M+, 100),
278 (9), 258 (83), 242 (14), 230 (20), 201 (15), 189 (11), 176 (6),
150 (8), 89 (8), 77 (48). Anal. Calcd for C19H16ClN (293): C,
77.68; H, 5.49; N, 4.77. Found: C, 77.59; H, 5.34; N, 4.68.
2-Ch lor o-11-p h en yl-7,8,9,10-tetr a h yd r o-6H-cycloh ep ta -
[b]qu in olin e (3p ): mp 175 °C; IR (KBr) ν ) 3063, 2955, 1603,
1560, 1482, 907, 707 cm-1; 1H NMR δ ) 0.93 (m, 2H), 1.26 (m,
2H), 1.56 (m, 2H), 2.67 (t, J ) 7 Hz, 2H), 3.27 (t, J ) 7.3 Hz,
2H), 7.1-7.97 (m, 8H); 13C NMR δ ) 26.8, 28.3, 30.6, 31.8, 40,
125, 127.8, 127.9, 128.5, 128.9, 129.2, 130.1, 131.2, 132.4,
134.8, 136.8, 144.1, 144.6, 165; MS m/z 307 (M+, 100), 292 (16),
278 (36), 253 (11), 241 (41), 216 (17), 203 (10), 189 (13), 176
(8), 167 (16), 149 (54), 126 (29), 95 (31), 82 (30), 71 (35), 57
(35). Anal. Calcd for C20H18ClN (307): C, 77.04; H, 5.89; N,
4.55. Found: C, 76.95; H, 5.74; N, 4.46.
6-Ch lor o-2,4-d ip h en ylqu in olin e (3t): mp 102 °C; IR
(KBr) ν ) 3056, 1684, 1483, 908, 730 cm-1; 1H NMR δ ) 7.4-8
(m, 14H); 13C NMR δ ) 120, 124.4, 126.4, 127.5, 128.7, 128.8,
129.4, 130.4, 131.6, 132.7, 137.7, 139.1, 147.2, 148.4, 157; MS
m/z 316 (M+, 29), 288 (100), 125 (8). Anal. Calcd for C21H14
-
ClN (316): C, 79.87; H, 4.47; N, 4.44. Found: C, 79.79; H, 4.38;
N, 4.38.
6-Ch lor o-2-(4-ch lor oph en yl)-4-ph en ylqu in olin e (3u ): mp
161 °C; IR (KBr) ν ) 3019, 1588, 1215, 755 cm-1 1H NMR
;
δ ) 7.48-8.15 (m, 13H); 13C NMR δ ) 119.5, 124.5, 126.5,
128.7, 128.8, 129, 129.4, 130.6, 131.7, 132.4, 135.8, 137.5,
147.2, 148.7, 155.7; MS m/z 349 (M+, 100), 314 (40), 278 (15),
236 (16), 201 (21), 176 (19), 157 (26), 139 (52), 125 (28), 112
(8), 87 (5), 75 (14), 63 (5). Anal. Calcd for C21H13Cl2N (349):
C, 72.01; H, 3.74; N, 4. Found: C, 71.95; H, 3.68; N, 3.92.
6-Ch lor o-2-(4-br om oph en yl)-4-ph en ylqu in olin e (3v): mp
195 °C; IR (KBr) ν ) 3018, 2928, 1645, 1580, 1215, 755 cm-1
;
1H NMR δ ) 7.55-8.11 (m, 13H); 13C NMR δ ) 119.4, 124.2,
124.5, 126.5, 128.2, 128.8, 129, 129.3, 129.8, 132, 132.5, 135.9,
137.5, 137.9, 147, 148.8, 155.6; MS m/z 394 (M+, 20), 300 (22),
288 (72), 242 (14), 230 (12), 200 (100), 125 (27). Anal. Calcd
for C21H13BrClN (394): C, 63.91; H, 3.32; N, 3.55. Found: C,
63.85; H, 3.28; N, 3.32.
9-Ch lor o-7-p h en yl-5,6-d ih yd r ob en zo[c]a cr id in e (3q ):
mp 130 °C; IR (KBr) ν ) 2960, 2860, 1600, 1488, 704 cm-1; 1H
NMR δ ) 2.86 (m, 4H), 7.25-8.61 (m, 12H); 13C NMR δ )
26.4, 28, 124.8, 126.3, 127.2, 127.4, 127.9, 128.4, 128.7, 129.1,
129.3, 129.8, 130.9, 131.1, 131.6, 132.4, 136.1, 139.2, 144.5,
145.5, 153.3, 167.7; MS m/z 341 (M+, 10), 279 (11), 167 (30),
149 (100), 104 (13), 77 (37). Anal. Calcd for C23H16ClN (341):
C, 80.81; H, 4.72; N, 4.10. Found: C, 80.65; H, 4.64; N, 4.
6-Ch lor o-2,3-d im eth yl-4-p h en ylqu in olin e (3r ): mp 127
Ack n ow led gm en t. S.S.P. thanks CSIR, New Delhi,
for providing a J unior Research Fellowship. We also
acknowledge financial assistance from Department of
Science and Technology (DST), New Delhi, Project No.
SR/S5/OC-23/2002).
1
°C; IR (KBr) ν ) 3063, 2954, 1605, 1484, 1215, 755 cm-1; H
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
data for compounds 3a -v and for all ionic liquids (ILs)
synthesized. This material is available free of charge via the
Internet at http://pubs.acs.org.
NMR δ ) 1.96 (s, 3H), 2.52 (s, 3H), 6.99-7.75 (m, 8H); 13C
NMR δ ) 16.9, 24.4, 124.8, 127.6, 128, 128.7, 128.9, 129.2,
130.1, 131.2, 136.8, 144.4, 145.5, 159.2; MS m/z 268 (M+, 100),
254 (18), 227 (19), 174 (75). Anal. Calcd for C17H14ClN (268):
C, 76.26; H, 5.27; N, 5.23. Found: C, 76.15; H, 5.14; N, 5.1.
J O035153U
9378 J . Org. Chem., Vol. 68, No. 24, 2003