Synthesis of ethyl 2-hydroxy-3-[aryl(2-naphthylamino)methyl]-2-cyclopentenecarboxylates and ethyl 3-arylmethylene-2-(2-naphthylamino)-1-cyclopentenecarboxylates

Article abstract of DOI:10.1023/A:1015398523999

Condensation of N-arylmethylene-2-naphthylamines with ethyl 2-oxocycopentanecarboxylate in the presence of HCl or CH₃COOH yields ethyl 2-hydroxy-3-[aryl(2-naphthylamino)methyl]-2-cyclopentene-carboxylates and ethyl 3-arylmethylene-2-(2-naphthyl

Full text of DOI:10.1023/A:1015398523999

Russian Journal of Organic Chemistry, Vol. 38, No. 1, 2002, pp. 59 62. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 1, 2002,
pp. 68 71.
Original Russian Text Copyright
2002 by Kozlov, Yakubovich.
Synthesis of Ethyl 2-Hydroxy-3-[aryl(2-naphthylamino)methyl]-
2-cyclopentenecarboxylates and Ethyl 3-Arylmethylene-
2-(2-naphthylamino)-1-cyclopentenecarboxylates
N. G. Kozlov and L. S. Yakubovich
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 13, Minsk, 220072 Belarus
Received February 7, 2001
Abstract Condensation of N-arylmethylene-2-naphthylamines with ethyl 2-oxocycopentanecarboxylate in
the presence of HCl or CH3COOH yields ethyl 2-hydroxy-3-[aryl(2-naphthylamino)methyl]-2-cyclopentene-
carboxylates and ethyl 3-arylmethylene-2-(2-naphthylamino)-1-cyclopentenecarboxylates, respectively.
Schiff bases are known to react with cyclic ketones
to give derivatives of benzo[f]quinoline or cyclic
enamines [1, 2]. We previously found [3] that reac-
tions of ethyl 2-oxocyclopentanecarboxylate with
N-arylmethylene-2-naphthylamines occur under mild
conditions (on heating for a short time in the presence
of a catalytic amount of HCl), leading to formation of
4-aryl-1-ethoxycarbonyl-2,3,4,5-tetrahydro-1H-cyclo-
penta[c]benzo[f]quinolines. When the reaction was
minutes previously unknown ethyl 2-hydroxy-3-[aryl-
(2-naphthylamino)methyl]-2-cyclopentenecarboxylates
IIIa IIIc were obtained in 27 41% yield (Scheme 1).
It should be emphasized that the substituent in the
aldehyde moiety of the Schiff base has no appreciable
effect on the yield of the target product. As expected,
electron-acceptor substituents slightly increase the
yield of benzo[f]quinolines (compound IIIa), while
electron-donor substituents exert the reverse effect
performed under more severe conditions in the pres- (IIIb and IIIc). This is explained by different degrees
ence of nitrobenzene, 4-aryl-1-ethoxycarbonyl-2,3-di-
hydro-1H-cyclopenta[c]benzo[f]quinolines were ob-
tained. The same reaction carried out in the presence
of nitrobenzene and excess HCl was accompanied by
decarboxylation of intermediate 4-aryl-1-ethoxycar-
bonyl-2,3-dihydro-1H-cyclopenta[c]benzo[f]quinolines
to afford 4-aryl-2,3-dihydro-1H-cyclopenta[c]benzo[f]-
quinolines.
of polarization of the C N bond in Schiff bases II
[4, 5]. Raising the temperature and reaction time leads
to formation of hitherto unknown ethyl 4-aryl-2,3,4,5-
tetrahydro-1H-cyclopenta[c]benzo[f]quinoline-1-car-
boxylates IVa and IVb. Compounds IVa and IVb
were also synthesized by heating of solutions of IIIb
and IIIc in ethanol at 60 C in the presence of HCl.
The reaction of ester I with Schiff bases II in the
presence of acetic acid involves intermediate forma-
tion of esters III which undergo decomposition into
The goal of the present work was to synthesize
ethyl 2-hydroxy-3-[aryl(2-naphthylamino)methyl]-2-
cyclopentenecarboxylates and ethyl 3-arylmethylene- the corresponding primary amine and , -unsaturated
2-(2-naphthylamino)-1-cyclopentenecarboxylates by
reaction of ethyl 2-oxocyclopentanecarboxylate (I)
with N-benzylidene-, N-(4-chlorobenzylidene)-,
N-(4-methoxybenzylidene)-, N-(4-nitrobenzylidene)-,
N-(3,4-dimethoxybenzylidene)-, and N-(3,4-methylene-
dioxybenzylidene)-2-naphthylamines IIa IIf. The
latter were prepared from 2-naphthylamine and the
corresponding aromatic aldehydes. We were the first
to reveal that the condensation of Schiff bases IIa IIc
with ester II occurs under mild conditions (at room
temperature in the absence of HCl). In several
ketone. The reaction between the decomposition prod-
ucts yields enamines Va Ve. These reactions were
carried out by heating ester I and Schiff base II in
boiling ethanol containing glacial acetic acid. The
yields of products V were 57 70%. Esters Vb Ve
can also be obtained by heating compounds IIIa and
IIIb in boiling ethanol in the presence of glacial
acetic acid. The yields, melting points, and elemental
analyses of the newly synthesized compounds are
given in Table. Their structure was confirmed by the
1
IR, H and 13C NMR, and mass spectra.
1070-4280/02/3801-0059$27.00 2002 MAIK Nauka/Interperiodica

60
KOZLOV, YAKUBOVICH
Scheme 1.
II, Ar = C6H5 (a), 4-ClC6H4 (b), 4-CH3OC6H4 (c), 4-NO2C6H4 (d), 3,4-(CH3O)2C6H3 (e), 3,4-OCH2OC6H3 (f); III, Ar = 4-ClC6H4
(a), 3,4-(CH3O)2C6H3 (b), 3,4-OCH2OC6H3 (c); IV, Ar = 3,4-(CH3O)2C6H3 (a), 3,4-OCH2OC6H3 (b); V, Ar = C6H5 (a),
4-ClC6H4 (b), 4-CH3OC6H4 (c), 4-NO2C6H4 (d), 3,4-(CH3O)2C6H3 (e).
The IR spectra of esters IIIa IIIc contain absorp-
tion bands belonging to stretching vibrations of O H
and 3.89 ppm, respectively. The signal from the
OCH2O group in IIIc and IVb is observed as a singlet
1
1
at
5.95 ppm. The downfield shift of this signal
(3420 3450 cm ), N H (3390 cm ), C O
1
1
relative to the usual position of signals from such
aliphatic protons [8] is likely to be caused by aniso-
tropic effect of the two oxygen atoms, in keeping with
our previous data [5]. The ethoxy group in esters III
and IV gives rise to a triplet at 0.70 ppm (CH3)
and a quartet at 3.87 ppm (CH2). Signals from the
(1690 cm ), and C O C bonds (1220 1230 cm ).
Compounds IVa and IVb show in the IR spectra
strong absorption bands at 3400 (N H), 1695 1700
1
(C O), and 1210 1220 cm (C O C). Esters
Va Ve are characterized by strong IR bands at 1670
1
(C O, chelated) and 1610 cm (C C, conjugated).
1
A band at 3300 cm arises from stretching vibrations
methylene protons on C4 and C5 in compounds III
and on C2 and C3 in compounds IV appear as multi-
plets centered at 3.00 and 1.95 ppm. The NH proton
of III and IV gives a singlet at 4.42 ppm.
of the N H bond [6, 7].
The mass spectra of compounds III V character-
istically contain a little of fragment ions. The mole-
cular ion peaks of III V have the following relative
intensities: III, 15%; IV, 30%; V, 12%. Also,
the [M C2H5]+ (60 70%) and [M COOC2H5]+
(15 20%) ion peaks are present.
In the 1H NMR spectra signals from aromatic
protons of the naphthalene and benzene rings appear
as a multiplet in the region 7.10 7.70 ppm (com-
pounds III and IV). The 9-H signal of III and 4-H
signal of IV are observed as singlets at 6.60 6.80
and 6.65 6.75 ppm, respectively. The methoxy group
in compounds IIIb and IVa gives a singlet at 3.90
1
Compound Ve shows in the H NMR spectrum
a triplet signal from CH3CH2O at 1.12 ppm, two
multiplets from the cyclopentene CH2 protons (4H) at
2.70 and 2.90 ppm, and a 6H-singlet at 3.70 ppm
from the two methoxy groups. Methylene protons of
the ethoxy group appear as a quartet at 4.05 ppm.
The singlet at 6.50 ppm belongs to 9-H. Aromatic
protons of the benzene and naphthalene rings give
three multiplets centered at 6.87 (3H), 7.32 (4H),
and 7.73 ppm (3H). The NH proton signal is observed
as a singlet at
8.70 ppm.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

SYNTHESIS OF ETHYL 2-HYDROXY-3-[ARYL(2-NAPHTHYLAMINO)METHYL]-.. .
61
Yields, melting points, and elemental analyses of compounds III V
Found, %
H
Calculated, %
Comp.
no.
Yield,
%
mp,
C
Formula
C
N
C
H
N
a
IIIa
IIIb
IIIc
IVa
IVb
Va
Vb
Vc
Vd
Ve
41
27
32
52
44
70
69
64
58
57
220 221
161 162
205 206
164 165
208 209
130 131
146 147
123 124
117 118
138 139
71.1
72.3
70.7
75.7
77.6
81.3
74.1
78.5
72.4
75.5
5.9
6.5
6.1
6.6
6.0
6.2
5.8
6.2
5.3
6.4
3.3
3.0
3.2
3.3
3.4
3.8
3.4
3.5
6.5
3.3
C25H24ClNO3
C27H29NO3
C26H25NO5
C27H27NO4
C26H23NO4
C25H23NO2
C25H22ClNO2
C26H25NO3
C25H22N2O4
C27H27NO4
71.2
72.5
70.7
75.5
77.4
81.3
74.4
78.2
72.5
75.5
5.7
6.5
6.0
6.3
5.7
6.2
5.5
6.3
5.3
6.3
3.3
3.1
3.1
3.3
3.5
3.8
3.5
3.5
6.8
3.2
b
a
Found Cl: 8.4%. Calculated Cl: 8.3%.
Found Cl: 8.9%. Calculated Cl: 8.8%.
b
EXPERIMENTAL
(C1), 59.48 s (C16), 59.48 s (C17), 63.26 t (C7),
67.93 d (C9), 110.48 s (C10), 115.1 d (C14), 115.57 d
(C11), 120.95 d (C19), 148.16 s (C2), 148.72 d (C18),
152.30 s (C12), 152.60 s (C13), 169.70 s (C6); IIIc:
17.03 t (C8), 27.54 t (C4), 37.2 t (C5), 52.9 s (C1),
63.26 t (C7), 67.82 d (C9), 104.68 s (C16), 110.53 s
(C10), 111.52 d (C14), 111.67 d (C11), 120.08 d (C18),
148.06 s (C2), 148.61 s (C17), 150.53 s (C13), 152.07 s
(C12), 169.97 s (C6).
The IR spectra were recorded on a Specord 75IR
spectrometer in KBr. The mass spectra were obtained
om an MKh-1320 instrument (energy of ionizing elec-
trons 70 eV; vaporizer temperature 130 200 C). The
NMR spectra were measured on BS-567A (1H) and
BS-587A spectrometers (13C) using CDCl3 or
DMCO-d6 as solvent and TMS as internal reference.
Ethyl 2-oxocyclopentanecarboxylate (I) was syn-
thesized by the procedure reported in [9]; yield 72%,
bp 102 103 C (13 mm), n2D0 = 1.4515.
Ethyl 4-aryl-2,3,4,5-tetrahydro-1H-cyclopenta-
[c]benzo[f]quinoline-1-carboxylates IVa and IVb.
a. To a solution of 0.003 mol of ester IIIa and IIIb
in 10 ml of ethanol we added 2 drops of concentrated
hydrochloric acid, and the mixture was heated for
3 min at 60 C. After cooling, a crystalline solid
precipitated and was filtered off, treated with
an aqueous solution of ammonia, and recrystallized
from ethanol.
b. To a solution of 0.01 mol of Schiff base IIe
or IIf in 25 30 ml of ethanol we added 3 drops of
concentrated hydrochloric acid and 0.01 mol of ester
I, and the mixture was heated for 5 min at 60 C. After
cooling, the precipitate was filtered off and treated
as described above in a.
Schiff bases IIa IIf. A mixture of 0.05 mol of
2-naphthylamine and 0.05 mol of appropriate aromatic
aldehyde in 50 ml of ethanol was heated for 15
20 min to 75 80 C. After cooling, the crystalline
precipitate was filtered off and recrystallized from
ethanol.
Ethyl 2-hydroxy-3-[aryl(2-naphthylamino)-
methyl]-2-cyclopentenecarboxylates IIIa IIIc. To
a solution of 0.01 mol of Schiff base IIIa IIIc in
25 30 ml of ethanol we added one drop of concen-
trated hydrochloric acid and 0.01 mol of ester I, and
the mixture was stirred at room temperature. After
2 3 min, a crystalline solid precipitated and was
filtered off, treated with an aqueous solution of am-
monia, and recrystallized from ethanol. 13C NMR
spectra, C, ppm: IIIa: 17.22 t (C8), 27.43 t (C4),
Ethyl 3-arylmethylene-2-(2-naphthylamino)-1-
cyclopentenecarboxylates Va Ve. a. A mixture of
0.01 mol of Schiff base IIa IIe, 0.012 mol of ester I,
7 ml of glacial acetic acid, and 7 ml of anhydrous
ethanol was refluxed for 15 20 min. The mixture was
cooled, and the precipitate was filtered off and recrys-
37.23 t (C5), 53.04 t (C1), 63.31 t (C7), 67.25 d (C9),
120.79 d (C17), 128.64 s (C10), 130.0 s (C3), 143.9 s
(C13), 147.87 s (C2), 148.09 s (C16), 169.54 s (C6);
IIIb: 17.31 t (C8), 27.72 t (C4), 37.29 t (C5), 52.9 s
tallized from ethanol. 13C NMR spectrum of Ve,
,
ppm: 18.13 t (C8), 31.35 t (C4), 32.04 t (C5), 59.35Cs
(C16), 59.35 s (C17), 63.03 t (C7), 115.5 d (C14),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

62
KOZLOV, YAKUBOVICH
115.9 d (C1), 117.7 d (C9), 151.9 s (C12), 152.2 s
(C13), 169.5 s (C6).
5. Kozlov, N.G., Gusak, K.N., and Makhnach, S.A.,
Khim. Geterotsikl. Soedin., 1996, no. 1, pp. 34 39.
b. Esters Vb and Ve were synthesized by the same
procedure, starting from compounds IIIa and IIIb.
6. Favorskaya, T.A., Fedorova, V.V., and Yakimo-
vich, S.I., Zh. Org. Khim., 1968, vol. 4, no. 7,
pp. 1493 1498.
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