Synthesis of aryl-N,N-bis(quinolin-8-yl)methanediamines

Article abstract of DOI:10.1134/S107036320911019X

Condensation of substituted benzaldehydes with 8-aminoquinoline in methanol gave the corresponding aryl-N,N-bis(quinolin-8-yl)methanediamines.

Full text of DOI:10.1134/S107036320911019X

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 11, pp. 2402–2405. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © E.A. Dikusar, N.G. Kozlov, V.I. Potkin, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 11, pp. 1880–1883.
Synthesis of Aryl-N,N′-bis(quinolin-8-yl)methanediamines
E. A. Dikusar, N. G. Kozlov, and V. I. Potkin
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 13, Minsk, 220072 Belarus
e-mail: evgen_58@mail.ru
Received April 16, 2009
Abstract—Condensation of substituted benzaldehydes with 8-aminoquinoline in methanol gave the
corresponding aryl-N,N′-bis(quinolin-8-yl)methanediamines.
DOI: 10.1134/S107036320911019X
1,1-Diamines (aminals) are relatively unstable
compounds, and they readily undergo hydrolysis [1].
Nevertheless, some 1,1-diamines exhibit strong bio-
logical activity [2–4].
1H NMR spectra, and the determination of molecular
weights by cryoscopy (see table). The IR spectra of
III–XL contained absorption bands due to vibrations
of the NH bonds (3472±5, 3373±5 cm–1, C–H bonds
in the aromatic rings (3080±3, 3060±5, 3037±3,
3003±1, 820±2, 791±2, 750±3 cm–1); aliphatic C–H
bonds (2965±5, 2935±5, 2900±5, 2835±3 cm–1),
aromatic C–C bonds (1604±4, 1595±5, 1575±3,
1508±3, 1474±3, 1419±5, 1376±3, 1335±2 cm–1),
and C–O bonds (1260±10, 1142±5, 1111±4, 1084±3,
1032±3 cm–1). In the IR spectra of esters VIII–XXV
and XXVII–XL, stretching vibrations of the ester
carbonyl group gave rise to absorption at 1755±15 cm–1.
The presence of a nitro group in molecule XXII is
confirmed by appearance of the characteristic absorp-
tion bands at 1539 and 1352 cm–1. Aminals III–XL
displayed the following absorption maxima in the
electronic spectra, λmax, nm (ε): 198 (61000), 251
(33000), 350 (8000).
The goal of the present work was to develop a
preparative procedure for the synthesis of aryl-N,N′-bis-
(quinolin-8-yl)methanediamines by condensation of
substituted benzaldehydes I with 8-aminoquinoline
(II). The reactions were carried out by heating the
reactants (I-to-II ratio 1:2) in boiling anhydrous
methanol over a period of 1.5–2 h. As a result, we
isolated the corresponding aryl-N,N′-bis(quinolin-8-yl)-
methanediamines III–XL having hydroxy, alkoxy, and
acyloxy groups in 92–98% yield. Mild reaction condi-
tions ensured conservation of labile ester groups (no
hydrolysis or aminolysis was observed). When the
reaction was performed with equimolar amounts of the
reactants with a view to obtain the corresponding Schiff
bases, in most cases the products were mixtures of
compounds aminals III–XL and initial benzaldehydes
I. We succeeded in isolating only Schiff base XLI
(yield 50%) in the reaction of 8-aminoquinoline (II)
with 4-hydroxy-3-methoxybenzaldehyde (vanillin) at a
ratio of 1:1; presumably, the formation of XLI was
favored by its poor solubility in a mixture of methanol
with diethyl ether. Analogous results were obtained
previously for structurally related compounds [5]. The
predominant formation of aminals III–XL rather than
Schiff bases (as in reactions of substituted benzal-
dehydes I with 1-aminonaphthalene [6]) is likely to be
determined by stabilizing effect of intramolecular
hydrogen bond [7].
1
In the H NMR spectra of III–XL, protons in the
NH groups resonated as a broadened singlet at δ 4.50–
6.50 ppm, and aromatic protons and CH(NH)2 gave
rise to a multiplet in the region 6.75–8.95 ppm.
Protons in the methoxy group appeared in the 1H NMR
spectra of V–XXV, XXVII, XXXVI, and XXXIX as a
singlet at δ 3.87–3.97 ppm, and compounds XXVI–
XXXVII and XL characteristically showed in the
spectra a triplet in the region δ 1.20–1.60 ppm and a
quartet at 3.90–4.30 ppm due to methyl and methylene
protons, respectively, in the ethoxy group. Signals
from the methyl protons in the acetyl group of acetates
VIII and XXVIII were located at δ 2.32 ppm.
Compounds III–XL are colorless or slightly
colored crystalline or glassy substances. Their struc-
ture was confirmed by elemental analyses, IR, UV, and
The IR spectrum of (E)-N-(4-hydroxy-3-methoxy-
benzylidene)quinolin-8-amine (XLI) contained an
absorption band at 1620 cm–1 due to stretching
2402

SYNTHESIS OF ARYL-N,N′-BIS(QUINOLIN-8-YL)METHANEDIAMINES
2403
N
CHO
NH2
N H
R1
R2
N
MeOH
R3
C
H
+
R2
R1
R3
N
H
N
I
II
III–XXXVII
R1 = R2 = R3 = H (III); R1 = R3 = HO, R2 = H (IV), R1 = R2 = H, R3 = MeO (V); R1 = H, R2 = MeO, R3 = HO (VI), MeO
(VII), MeCO2 (VIII), EtCO2 (IX), PrCO2 (X), Me2CHCO2 (XI), BuCO2 (XII), Me2CHCH2CO2 (XIII), Me(CH2)6CO2
(XIV), Me(CH2)8CO2 (XV), Me(CH2)16CO2 (XVI), H2C=CMeCO2 (XVII), C6H5MeCHCH2CO2 (XVIII), C6H5CO2 (XIX),
2,4-Cl2C6H3CO2 (XX), 4-BrC6H4CO2 (XXI), 3-O2NC6H4CO2 (XXII), 1-AdCO2 (XXIII), MeOCO2 (XXIV); EtOCO2
(XXV); R2 = EtO, R3 = HO (XXVI), MeO (XXVII), MeCO2 (XXVIII), EtCO2 (XXIX), PrCO2 (XXX), Me2CHCO2
(XXXI), BuCO2 (XXXII), Me2CHCH2CO2 (XXXIII), 4-MeC6H4CO2 (XXXIV), 1-AdCO2 (XXXV), MeOCO2 (XXXVI);
EtOCO2 (XXXVII).
N
N
H
N
N
N
N
H
H
C
X C
H
H
H
N
N
XXXVIII–XL
X = 4,4'-C6H4C6H4 (XXXVIII),
(XXXIX, XL); R4 = Me (XXXIX), Et (XL).
R4O
OR4
OC(O)CH2CH2C(O)O
vibrations of the azomethine C=N bond, and the
CH=N proton resonated at δ 8.47 ppm in the H NMR
spectrum. In the UV spectrum of XLI, we observed
absorption maxima at λ 198 (ε 48000), 254 (25000),
and 345 mm (10000).
UV spectra were measured on a Specord UV-Vis
spectrophotometer from 1×10–4 M solutions in
methanol. The H NMR spectra were obtained on a
Tesla BS-587A instrument (100 MHz) from 5%
solutions in chloroform-d or DMSO-d6 using
tetramethylsilane as internal reference. The elemental
compositions were determined with an accuracy of
±0.1% on an Elementar Vario EL-III C,H,N,O,S-
analyzer. The molecular weights (M) were measured
by cryoscopy in benzene.
1
1
EXPERIMENTAL
The IR spectra were recorded in KBr on a Nicolet
Protégé-460 spectrometer with Fourier transform. The
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

2404
DIKUSAR et al.
Yields, melting points, elemental analyses, and molecular weights of compounds III–XLI
Found, %
H
Calculated, %
M
Comp. no. Yield, %
mp, °C
Formula
C
N
C
H
N
found
calculated
93
92
94
94
97
98
96
97
98
95
92
93
94
96
93
95
98
96
97
95
98
92
94
93
93
92
94
93
93
94
93
–
80.12
73.82
77.03
74.10
74.75
72.68
5.48
5.10
5.62
5.35
5.73
5.34
5.65
5.87
5.83
6.13
6.10
6.80
7.18
8.22
5.47
5.89
5.16
4.16
4.23
4.52
6.34
5.20
5.67
5.72
6.02
5.48
5.80
6.18
6.12
6.29
6.35
14.47
13.28
13.32
12.93
12.52
11.65
11.32
11.02
10.99
10.63
10.88
9.96
C25H20N4
79.76
73.51
76.83
73.92
74.29
72.40
72.79
73.15
73.15
73.50
73.50
74.43
74.97
76.71
73.45
76.04
75.27
66.56
65.46
69.34
76.00
69.99
70.43
74.29
74.65
72.79
73.15
73.50
73.50
73.82
73.82
5.35
4.94
5.46
5.25
5.54
5.21
5.48
5.73
5.73
5.97
5.97
6.61
6.99
8.19
5.34
5.67
4.98
4.06
4.16
4.41
6.21
5.03
5.30
5.54
5.82
5.48
5.73
5.97
5.97
6.20
6.20
14.88
13.72
13.78
13.26
12.84
12.06
11.71
11.37
11.37
11.06
11.06
10.21
9.71
361.7
387.6
388.1
401.8
419.6
448.0
462.3
473.4
476.6
488.2
484.7
532.7
553.8
652.5
472.9
546.2
502.3
580.4
581.6
566.2
552.9
453.4
472.5
425.4
431.0
453.7
470.2
482.4
480.3
505.8
512.2
376.5
408.5
406.5
422.5
436.5
464.5
478.5
492.6
492.6
506.6
506.6
548.7
576.7
688.9
490.6
568.7
526.6
595.5
605.5
571.6
584.7
480.5
494.5
436.5
450.5
478.5
492.6
506.6
506.6
520.6
520.6
III
68–69
C25H20N4O2
C26H22N4O
C26H22N4O2
C27H24N4O2
C28H24N4O3
C29H26N4O3
C30H28N4O3
C30H28N4O3
C31H30N4O3
C31H30N4O3
C34H36N4O3
C36H40N4O3
C44H56N4O3
C30H26N4O3
C36H32N4O3
C33H26N4O3
C33H24Cl2N4O3
C33H25BrN4O3
C33H25N5O5
C37H36N4O3
C28H24N4O4
C29H26N4O4
C27H24N4O2
C28H26N4O2
C29H26N4O3
C30H28N4O3
C31H30N4O3
C31H30N4O3
C32H32N4O3
C32H32N4O3
IV
–
V
–
–
VI
VII
99–100
VIII
IX
143–144 73.09
123–124 73.58
128–129 73.60
120–121 73.94
X
XI
XII
–
74.01
74.79
75.40
77.08
XIII
XIV
XV
72–73
71–72
50–51
9.28
7.73
8.13
XVI
XVII
XVIII
XIX
XXa
155–156 73.92
67–68 76.41
121–122 75.66
81–82 66.84
102–103 65.84
92–93 69.57
11.03
9.45
11.42
9.85
10.24
9.07
10.64
9.41
XXIb
XXII
XXIII
XXIV
XXV
XXVI
XXVII
XXVIII
XXIX
XXX
XXXI
XXXII
XXXIII
8.96
9.25
12.03
9.17
12.25
9.58
191–192 76.48
122–123 70.32
126–127 70.88
121–122 74.67
11.28
10.98
12.35
11.97
11.32
11.02
10.86
10.82
10.33
10.34
11.66
11.33
12.84
12.44
11.71
11.37
11.06
11.06
10.76
10.76
–
74.99
73.10
95–96
142–143 73.43
128–129 73.58
140–141 73.87
106–107 74.19
–
74.12
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009

SYNTHESIS OF ARYL-N,N′-BIS(QUINOLIN-8-YL)METHANEDIAMINES
2405
Table. (Contd.)
Found, %
H
Calculated, %
H
M
Comp. no. Yield, %
mp, °C
Formula
C
N
C
N
found
calculated
98
95
94
94
96
95
95
50
121–122
197–198
76.00
76.64
5.68
6.72
5.21
5.29
5.19
5.24
5.38
5.19
9.75
9.04
C35H30N4O3
C38H38N4O3
C29H26N4O4
C30H28N4O4
C50H38N8
75.79
76.23
70.43
70.85
79.98
72.56
72.94
73.37
5.45
6.40
5.30
5.55
5.10
5.00
5.28
5.07
10.10
9.36
538.7
582.4
478.3
486.5
731.3
901.6
938.8
265.4
554.6
598.7
494.5
508.6
750.9
927.0
955.1
278.3
XXXIV
XXXV
XXXVI
XXXVII
XXXVIII
XXXIX
XL
138–139 70.25
137–138 71.12
118–119 80.38
11.23
10.84
14.65
11.76
11.25
9.84
11.33
11.02
14.92
12.09
11.73
10.07
81–82
73–74
72.85
73.25
73.45
C56H46N8O6
C58H50N8O6
C17H14N2O2
184–185
XLI
a
Found Cl, %: 11.67. Calculated Cl, %: 11.91. b Found Br, %: 12.87. Calculated Br, %: 13.20.
Initial vanillin and vanillal esters were synthesized
through a glass frit, washed with a small amount of
diethyl ether, and dried in air.
according to the procedures reported in [8–11]; 8-
aminoqionoline (II) was commercial product of
analytical grade, purity 99%, mp 59–60°C.
REFERENCES
Aryl-N,N′-bis(quinolin-8-yl)methanediamines
III–XL (general procedure). A solution of 5 mmol of
substituted benzaldehyde I and 10 mmol of 8-
aminoqionoline (II) in 50 ml of anhydrous methanol
was heated for 1.5–2 h under reflux. In the synthesis of
bis-aminals XXXVI–XL, 5 mmol of the corresponding
dialdehyde and 20 mmol of 8-aminoqionoline (II)
were taken. The hot solution was filtered through a
filter paper, and the filtrate was cooled and left to stand
for 10–15 h at 5°C. Crystalline products were
separated by filtration through a glass porous filter,
washed with a small amount of methanol, and dried in
air. Liquid glassy products were separated by
decanting and dissolved in anhydrous diethyl ether, the
solution was filtered through a filter paper, and the
solvent was removed under reduced pressure.
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(E)-2-Methoxy-4-{[(quinolin-8-yl)imino]methyl}-
phenol (XLI). A solution of 5 mmol of 4-hydroxy-3-
methoxybenzaldehyde (vanillin) and 5 mmol of 8-
aminoqionoline (II) in 50 ml of anhydrous methanol–
diethyl ether (1:1) was heated for 30 min under reflux.
The hot solution was filtered through a folded filter
paper, and the filtrate was cooled and left to stand for
10–15 h at 5°C. The precipitate was filtered off
p. 1043.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 11 2009