An efficient green MCR protocol for the synthesis of new Betti bases via Mannich-type reaction

Article abstract of DOI:10.2174/157017812801322499

An efficient solvent and catalyst-free synthesis of new Betti base derivatives via Mannich-type one-pot threecomponent condensation reaction of aminodiazines, salicylaldehyde and naphthols under solvent-free conditions is described. The reactions occur at

Full text of DOI:10.2174/157017812801322499

Letters in Organic Chemistry, 2012, 9, 451-456
451
An Efficient Green MCR Protocol for the Synthesis of New Betti Bases via
Mannich-Type Reaction
Abolfazl Olyaeia,*, Mojgan Zarnegara, Mahdieh Sadeghpourb and Mortaza Rezaeia
aDepartment of Chemistry, Payame Noor University, PO BOX 19395-3697, Tehran, Iran
bDepartment of Chemistry, Islamic Azad University, Takestan Branch, Qazvin, Iran
Received January 03, 2012: Revised April 13, 2012: Accepted May 07, 2012
Abstract: An efficient solvent and catalyst-free synthesis of new Betti base derivatives via Mannich-type one-pot three-
component condensation reaction of aminodiazines, salicylaldehyde and naphthols under solvent-free conditions is de-
o
scribed. The reactions occur at 80 C giving high to excellent yields of the products. The work-up procedure is very sim-
ple and the products do not require further purification with column chromatography.
Keywords: Aminodiazine, Betti base, naphthol, salicylaldehyde, solvent-free, three- component.
INTRODUCTION
one-pot synthesis of new Betti bases through a three-compo-
nent condensation reaction of aminodiazines, salicylaldehyde
and naphthols under solvent-free conditions.
Study of the chemistry of the Betti bases started at the
beginning of the 20th century, when Betti reported the syn-
thesis of 1-(ꢀ-aminobenzyl)-2-naphthol [1]. The preparation
of substituted Betti base derivatives by the modified Manni-
ch reaction has subsequently become of considerable impor-
tance because a C-C bond is formed under mild experimental
conditions. The Betti procedure could be extended to diffe-
rent amines instead of ammonia, as shown by the earlier
work of Littman and Brode [2]. In addition, a variety of ami-
nes such as (CH3)2NH [2], piperidine [2], n-Bu-NH2 [3], pyr-
rolidine [4], heteroaryl amines [5], cyclic secondary amines
[6] and chiral amines [7-9] have recently been reported for
the synthesis of the Betti base derivatives. Traditionally, the
Betti base derivatives synthesis is carried out in organic sol-
vents such as EtOH, MeOH, and Et2O at room temperature
for long times and microwave irradiation [6] in the presence
of acid catalyst.
RESULTS AND DISCUSSION
Our literature survey at this stage revealed that, there is
no report yet available on the synthesis of 1-(2-hydroxy-
phenyl(diazineamino)methyl)naphthols under solvent-free
conditions. The aim of this present protocol is to highlight
the synergistic effect of the combined use of multi compo-
nent reactions (MCRs) and solvent-free conditions for the
development of new eco-compatible strategy for aminonaph-
thols synthesis.
Initially, the one-pot, three-component coupling reaction
of 2-aminopyrimidine, salicylaldehyde and 2-naphthol was
examined under solvent-free conditions at 70–120 oC and the
o
results demonstrated that 80 C appeared to be the optimum
temperature. Thus, the best yield in minimum time of the
product 3a was achieved under solvent-free conditions at
80 oC.
Preparation of the enantiomers of the Betti bases is of
significance science they can serve as chiral catalyst or the
nonracemic Betti base can be applied successfully as a new
chiral auxiliary [10-14]. Betti base derivatives also provide
convenient access to many useful synthetic building blocks
because the amino and phenolic hydroxy groups can be
converted into a wide variety of compounds [15, 16].
Encouraged by the remarkable results obtained with the
above reaction conditions, and in order to show the general-
ity and scope of this new protocol, we used various aminodi-
azines 1a-d (2-aminopyrimidine, 2-amino-4,6-dimethylpyri-
midine, 2-amino-4-methylpyrimidine and 2-amino-4-chloro-
6-methylpyrimidine), naphthols 2a-d (2-naphthol, 1-
naphthol, 2,7-dihydroxynaphthalene and 2,3-dihydroxyna-
phthalene) and salicylaldehyde in the synthesis of new Betti
bases (3a-k) with high to excellent yields (Scheme 1). The
results of the above mentioned reactions are shown in Table
1.
Our long interest in the chemistry of nitrogen-containing
heteroaromatic systems and green chemistry, recently led us
to discover that synthesis of new Betti bases was carried out
from 2-naphthol, arylaldehydes and heteroarylamines in wa-
ter solvent [5]. The most striking novelty of this method is
the use of water as a reactin solvent. In continuation of our
efforts for the development of multi-component condensa-
tion reactions [17-19] we have explored a straightforward
We proposed the mechanism for the formation of these
compounds. We assume that imine generated in situ from the
reaction of amine and salicylaldehyde in the first step. Then,
in the second step imine reacts with naphthol affording the
corresponding aminonaphthol. To make insight into the reac-
*Address correspondence to this author at the Department of Chemistry,
Payame Noor University, PO BOX 19395-3697, Tehran, Iran; Tel: 0098-
281-2224024; Fax: 0098-281-2226400; E-mail: olyaei_a@pnu.ac.ir
1875-6255/12 $58.00+.00
© 2012 Bentham Science Publishers

452 Letters in Organic Chemistry, 2012, Vol. 9, No. 6
NH2
Olyaei et al.
OH
X
CHO
Z
W
Y
N
N
Solvent-free
80oC
Aminonaphthols
+
+
Y'
X'
3
2
1
11 Examples
Scheme 1. Synthesis of new Betti base derivatives 3.
Table 1. Synthesis of Betti Base Derivatives Under Solvent-Free Conditions at 80 oC
Yield (%)
Time (Min)
3
Product
Naphthol
Amine
Entry
HO
N
N
NH2
HN
OH
OH
OH
90
25
3a
1
N
N
OH
OH
OH
HO
HN
N
N
NH2
92
30
3b
2
N
N
HO
HN
N
N
NH2
87
30
3c
3
N
N
Cl
HO
HN
N
NH2
OH
85
30
3d
4
N
N
N
OH
Cl
N
OH
NH2
OH HN
N
87
25
3e
5
N
N
HO
N
OH
NH2
OH HN
N
88
25
3f
6
N
N
HO

An Efficient Green MCR Protocol for the Synthesis of New Betti Bases
Letters in Organic Chemistry, 2012, Vol. 9, No. 6 453
Table 1. contd….
Yield (%)
Time (Min)
3
Product
Naphthol
Amine
Entry
HO
N
N
NH2
HN
HO
HO
HO
OH
OH
OH
93
30
3g
7
N
N
HO
OH
HO
HN
N
NH2
N
HO
91
3h
8
N
N
OH
HO
HN
N
NH2
N
91
30
3i
9
N
N
HO
OH
Cl
HO
HN
N
N
NH2
HO
OH
86
25
3j
10
N
N
HO
OH
Cl
HO
HN
N
NH2
OH
N
89
25
3k
11
N
N
OH
OH
OH
tion mechanism, we initially studied the reaction of 2-
naphthol with salicylaldehyde. No reaction progress was
observed during several hours. When the Schiff base product
obtained from 2-aminopyrimidine condensation with salicy-
laldehyde was treated with 2-naphthol under the reaction
conditions, the corresponding Betti base derivative was ob-
tained (Scheme 2). Notably, a wide range of heteroary-
lamines with electron donating and electron withdrawing
groups and naphthols were well tolerated under the reaction
conditions. However, negative charge on the nitrogen in the
intermediate, was stabilized with heteroaryl and the reactions
proceeded very fast.
tons should have appeared in the region of aromatic on the
basis of integration. Hydroxyl protons presented as broad
signals at about ꢀ 9.68-10.21 ppm due to the formation of
hydrogen bonding. The OH and NH absorptions are ob-
served at 3250–3400 cm-1 in the IR spectra. This Compound
exhibits the expected parent ions with medium intensity in
mass spectra.
CONCLUSION
In summary, we have successfully developed a quick,
convenient, and efficient method for the synthesis of new
aminonaphthol (Betti base) derivatives. This protocol is en-
dowed with several advantages such as improved yields,
clean reaction, easy operation, obtaining pure products wi-
thout futhure purification by column chromatography, sol-
vent and catalyst-free conditions, low reaction times and
Identification of products 3a–k was carried out on the ba-
1
sis of spectroscopic information. For example, the H NMR
spectrum of compound 3a the pyrimidinyl moieties are ex-
hibited as two well-resolved AB2 spin systems at about ꢀ
6.57 and 8.29 ppm. The methine, amine and aromatic pro-

454 Letters in Organic Chemistry, 2012, Vol. 9, No. 6
Olyaei et al.
HO
N
OH
NH2
+
N
N
N
N
CHO
OH
N
N
N
N
N
HN
H
O
HO
Scheme 2.
12H, Ar-H, methine-H and NH), 8.29 (d, 2H, J = 4.76 Hz,
pyrimidine-H4,6), 9.68 (br, 1H, OH), 10.21 (br, 1H, OH)
ppm; 13C NMR (125 MHz, DMSO-d6): 47.71, 111.40,
116.22, 119.54, 119.74, 120.24, 123.32, 124.22, 126.95,
128.55, 129.11, 129.13, 129.47, 129.57, 129.64, 133.33,
153.92, 155.47, 159.99, 162.23 ppm; MS (EI): m/z 343 (M+),
279, 265, 167, 149, 113; Anal. calcd. For C21H17N3O2: C,
73.47; H, 4.95; N, 12.24. Found: C, 73.52; H, 4.99; N, 12.31.
obtaining high to excellent yields merits recommendation to
the users. These compounds are potential chelating agents
for metal ions and synthesis of novel aminoxanthene deriva-
tives and this aspect is currently under study in our research
laboratory.
EXPERIMENTAL
All commercially available chemicals and reagents were
used without further purification. Melting points were de-
termined with an Electrothermal model 9100 apparatus and
are uncorrected. IR spectra were recorded on a Shimadzu
1-(2-Hydroxyphenyl(2-(4,6-dimethylpyrimidinyl)amino)
methyl)naphthalene-2-ol (3b)
M.P = 164-166 o C; IR (KBr): 3376, 3054, 2998, 1588,
1371, 1232, 824 cm-1; 1H NMR (500 MHz, DMSO-d6): 2.21
(s, 6H, 2xCH3), 6.38 (s, 1H, pyrimidine-H5), 6.70-8.19 (m,
12H, Ar-H, methine-H and NH), 10.25 (br, 1H, OH), 10.44
(br, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): 24.18,
48.24, 110.24, 117.05, 119.79, 119.92, 120.09, 123.46,
127.13, 128.37, 128.74, 129.12, 129.15, 129.23, 129.50,
129.72, 130.14, 133.08, 153.64, 155.34, 161.77 ppm; MS
(EI): m/z 371 (M+), 247, 231, 144, 124, 115, 108, 93; Anal.
calcd. For C23H21N3O2: C, 74.39; H, 5.66; N, 11.32. Found:
C, 74.32; H, 5.72; N, 11.30.
1
4300 spectrophotometer. The H and 13C NMR spectra were
recorded in DMSO-d6 on Bruker DRX-500 and 300 Avance
spectrometers. Chemical shifts (ꢀ) are reported in parts per
million and are referenced to the NMR solvent. Mass spectra
of the products were obtained with a HP (Agilent technolo-
gies) 5937 mass selective detector. Elemental analyses were
carried out by a CHN–O–Rapid Heraeus elemental analyzer
(Wellesley, MA).
General Procedure for the Synthesis of 1-(2-hydroxy
Phenyl(diazineamino)methyl)naphthols (3a–k)
1-(2-Hydroxyphenyl(2-(4-methylpyrimidinyl)amino)methyl)
naphthalene-2-ol (3c)
A mixture of aminodiazine 1 (1.0 mmol), salicylaldehyde
(1.0 mmol) and naphthol 2 (1.0 mmol) was magnetically
stirred on a preheated oil bath at 80 °C for the appropriate
amount of time as indicated in Table 1. The progress of the
reaction was monitored by thin-layer chromatography
(TLC). After completion, the reaction mixture was cooled to
room temperature and EtOH (5 mL) was added until solid
products precipitated. The precipitate was filtered, washed
with cold ethanol and dried. The crude product was stirred
for 5 min in boiling EtOH and the resulting white precipitate
was filtered. The obtained products 3 were found to be pure
upon TLC examination.
M.P = 173-174 o C; IR (KBr): 3375, 3052, 2998, 1583,
1
1521, 1443, 1236, 801 cm-1; H NMR (500 MHz, DMSO-
d6): 2.24 (s, 3H, CH3), 6.48 (d, 1H, J = 4.99 Hz, pyrimidine-
H5), 6.69-8.27 (m, 12H, Ar-H, methine-H and NH), 8.16 (d,
1H, J = 4.99 Hz, pyrimidine-H6), 9.87 (br, 1H, OH), 10.30
(br, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): 24.45,
47.89, 110.91, 116.52, 119.68, 119.75, 120.24, 123.37,
124.10, 125.70, 127.01, 128.60, 129.10, 129.47, 129.62,
129.87, 130.50, 133.22, 153.79, 155.39, 158.52, 162.00 ppm;
MS (EI): m/z 357 (M+), 247, 231, 213, 144, 121, 116, 110,
94; Anal. calcd. For C22H19N3O2: C, 73.95; H, 5.32; N,
11.76. Found: C, 74.02; H, 5.40; N, 11.64.
1-(2-Hydroxyphenyl(2-pyrimidinylamino)methyl)naphtha-
lene-2-ol (3a)
1-(2-Hydroxyphenyl(2-(4-chloro-6-methylpyrimidinyl)
amino)methyl)naphthalene-2-ol (3d)
M.P = 187-189 o C; IR (KBr): 3406, 3049, 2950, 1594,
M.P = 142-143 o C; IR (KBr): 3375, 3061, 2990, 1570,
1
1534, 1385, 1247, 804 cm-1; H NMR (500 MHz, DMSO-
1
1521, 1430, 1267, 812 cm-1; H NMR (500 MHz, DMSO-
d6): 6.57 (t, 1H, J = 4.76 Hz, pyrimidine-H5), 6.69-8.32 (m,
d6): 2.22 (s, 3H, CH3), 6.57 (s, 1H, pyrimidine-H5), 6.68-

An Efficient Green MCR Protocol for the Synthesis of New Betti Bases
Letters in Organic Chemistry, 2012, Vol. 9, No. 6 455
8.33 (m, 12H, Ar-H, methine-H and NH), 9.55 (br, 1H, OH),
10.14 (br, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6):
24.29, 47.79, 108.89, 109.40, 116.03, 119.39, 119.61,
119.99, 123.25, 124.39, 126.84, 128.60, 128.92, 129.07,
129.48, 129.63, 133.35, 153.97, 155.50, 160.79, 161.98,
170.73 ppm; MS (EI): m/z 391 (M+), 248, 231, 144, 128,
115, 93; Anal. calcd. For C22H18ClN3O2: C, 67.43; H, 4.59;
N, 10.72. Found: C, 67.50; H, 4.67; N, 10.70.
156.33, 161.27 ppm; MS (EI): m/z 387 (M+), 247, 231, 189,
160, 131, 108, 95; Anal. calcd. For C23H21N3O3: C, 71.31; H,
5.42; N, 10.85. Found: C, 71.40; H, 5.32; N, 10.80.
1-(2-Hydroxyphenyl(2-(4-methylpyrimidinyl)amino)methyl)
naphthalene-2,7-diol (3i)
o
M.P = 168-169 C; IR (KBr): 3376, 3052, 2985, 1584,
1523, 1227, 823 cm-1; 1H NMR (500 MHz, DMSO-d6): 2.26
(s, 3H, CH3), 6.48 (d, 1H, J = 4.95 Hz, pyrimidine-H5), 6.67-
7.61 (m, 11H, Ar-H, methine-H and NH), 8.17 (d, 1H, J =
4.95 Hz, pyrimidine-H6), 9.65 (s, 1H, OH), 10.04 (br, 1H,
OH), 10.18 (br, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-
d6): 24.42, 48.39, 106.03, 110.87, 115.92, 116.29, 116.71,
118.21, 119.65, 123.89, 128.68, 129.42, 129.52, 129.72,
130.71, 134.97, 154.15, 155.69, 156.63, 158.25, 158.52,
161.94 ppm; MS (EI): m/z 373 (M+), 247, 213, 160, 131,
109, 94; Anal. calcd. For C22H19N3O3: C, 70.77; H, 5.09; N,
11.26. Found: C, 70.61; H, 5.11; N, 11.31.
1-(2-Hydroxyphenyl(2-(4,6-dimethylpyrimidinyl)amino)
methyl)naphthalene-1-ol (3e)
o
M.P = 170-171 C; IR (KBr): 3382, 3058, 2996, 1585,
1384, 1249, 809 cm-1; 1H NMR (300 MHz, DMSO-d6): 2.26
(s, 6H, 2xCH3), 6.30 (s, 1H, pyrimidine-H5), 6.35-8.22 (m,
12H, Ar-H, methine-H and NH), 9.70 (br, 1H, OH), 10.26
(br, 1H, OH) ppm; 13C NMR (75 MHz, DMSO-d6): 23.69,
48.46, 109.82, 115.78, 119.10, 119.38, 122.84, 124.38,
125.22, 125.93, 126.21, 126.79, 127.66, 128.33, 128.44,
128.50, 128.55, 133.70, 150.41, 154.41, 161.52 ppm; MS
(EI): m/z 371 (M+), 247, 231, 207, 160, 124, 107, 91; Anal.
calcd. For C23H21N3O2: C, 74.39; H, 5.66; N, 11.32. Found:
C, 74.44; H, 5.60; N, 11.35.
1-(2-Hydroxyphenyl(2-(4-chloro-6-methylpyrimidinyl)
amino)methyl)naphthalene-2,7-diol (3j)
o
M.P = 180-182 C; IR (KBr): 3356, 3050, 2991, 1557,
1523, 1221, 828 cm-1; 1H NMR (300 MHz, DMSO-d6): 2.33
(s, 3H, CH3), 6.58 (s, 1H, pyrimidine-H5), 6.63-7.59 (m,
11H, Ar-H, methine-H and NH), 9.49 (s, 1H, OH), 9.81 (br,
2H, OH) ppm; 13C NMR (75 MHz, DMSO-d6): 23.85, 47.90,
105.80, 108.98, 115.39, 115.82, 117.57, 118.93, 123.42,
128.22, 128.39, 129.07, 129.50, 130.19, 134.68, 153.95,
155.34, 156.11, 160.52, 161.52, 163.64, 170.28 ppm; MS
(EI): m/z 407 (M+), 247, 218, 189, 160, 143, 128, 108, 93;
Anal. calcd. For C22H18ClN3O3: C, 64.78; H, 4.41; N, 10.30.
Found: C, 64.80; H, 4.50; N, 10.33.
1-(2-Hydroxyphenyl(2-(4-methylpyrimidinyl)amino)methyl)
naphthalene-1-ol (3f)
o
M.P = 188-189 C; IR (KBr): 3377, 3055, 2990, 1581,
1520, 1243, 802 cm-1; 1H NMR (300 MHz, DMSO-d6): 2.27
(s, 3H, CH3), 6.41 (d, 1H, J = 4.80 Hz, pyrimidine-H5), 6.50-
8.19 (m, 12H, Ar-H, methine-H, pyrimidine-H6 and NH),
9.41 (br, 1H, OH), 9.71 (br, 1H, OH) ppm; 13C NMR (75
MHz, DMSO-d6): 23.96, 48.54, 110.43, 115.70, 117.69,
119.21, 119.34, 122.67, 124.49, 125.22, 125.78, 126.13,
126.77, 127.76, 128.25, 128.58, 128.80, 133.71, 150.15,
154.58, 158.03, 161.67 ppm; MS (EI): m/z 357 (M+), 248,
247, 231, 189, 165, 144, 110, 94; Anal. calcd. For
C22H19N3O2: C, 73.95; H, 5.32; N, 11.76. Found: C, 73.91;
H, 5.25; N, 11.71.
1-(2-Hydroxyphenyl(2-(4,6-dimethylpyrimidinyl)amino)
methyl)naphthalene-2,3-diol (3k)
o
M.P = 171-172 C; IR (KBr): 3420, 3050, 2990, 1580,
1367, 1240, 748 cm-1; 1H NMR (300 MHz, DMSO-d6): 2.22
(s, 6H, 2xCH3), 6.31 (s, 1H, pyrimidine-H5), 6.34-8.24 (m,
11H, Ar-H, methine-H and NH), 9.30 (br, 1H, OH), 9.68 (br,
2H, OH), 10.34 (br, 1H, OH) ppm; 13C NMR (75 MHz,
DMSO-d6): 23.75, 48.06, 109.15, 109.87, 116.84, 119.65,
120.40, 123.07, 123.48, 123.55, 123.65, 126.80, 127.00,
128.44, 129.03, 129.33, 129.73, 145.18, 146.62, 154.90,
161.28 ppm; MS (EI): m/z 387 (M+), 315, 273, 247, 227,
160, 123, 108, 91; Anal. calcd. For C23H21N3O3: C, 71.31; H,
5.42; N, 10.85. Found: C, 71.24; H, 5.51; N, 10.88.
1-(2-Hydroxyphenyl(2-pyrimidinylamino)methyl)naphtha-
lene-2,7-diol (3g)
o
M.P = 180-181 C; IR (KBr): 3364, 3052, 2995, 1600,
1531, 1218, 817 cm-1; 1H NMR (500 MHz, DMSO-d6): 6.56
(t, 1H, J = 4.72 Hz, pyrimidine-H5), 6.67-7.62 (m, 11H, Ar-
H, methine-H and NH), 8.29 (d, 2H, J = 4.72 Hz, pyrimidine-
H4,6), 9.64 (s, 1H, OH), 9.75 (br, 1H, OH), 10.09 (br, 1H,
OH) ppm; 13C NMR (125 MHz, DMSO-d6): 48.12, 106.19,
111.34, 115.88, 116.10, 116.29, 118.29, 119.46, 123.89,
128.58, 129.43, 129.48, 130.69, 135.09, 154.32, 155.75,
156.57, 158.88, 158.97, 162.19 ppm; MS (EI): m/z 359 (M+),
264, 247, 199, 160, 131, 95; Anal. calcd. For C21H17N3O3: C,
70.19; H, 4.73; N, 11.70. Found: C, 70.25; H, 4.65; N, 11.78.
ACKNOWLEDGMENT
The authors thank the Research Council of Payame Noor
University for financial support.
1-(2-Hydroxyphenyl(2-(4,6-dimethylpyrimidinyl)amino)
methyl)naphthalene-2,7-diol (3h)
CONFLICT OF INTEREST
o
Declared none.
M.P = 178-180 C; IR (KBr): 3376, 3247, 3057, 2995,
1588, 1532, 1228, 835 cm-1; H NMR (300 MHz, DMSO-
1
d6): 2.28 (s, 6H, 2xCH3), 6.30 (s, 1H, pyrimidine-H5), 6.39-
7.78 (m, 11H, Ar-H, methine-H and NH), 9.50 (s, 1H, OH),
9.65 (br, 1H, OH), 10.34 (br, 1H, OH) ppm; 13C NMR (75
MHz, DMSO-d6): 23.74, 48.42, 105.34, 109.81, 115.58,
115.88, 116.95, 117.56, 119.52, 123.49, 128.47, 129.15,
129.21, 129.30, 129.60, 130.37, 134.41, 153.55, 155.26,
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