Trityl chloride as an efficient organic catalyst for the synthesis of 1-amidoalkyl-2-naphtols in neutral media at room temperature

Article abstract of DOI:10.1016/j.apcata.2010.07.057

A highly efficient and simple procedure for the preparation of 1-amidoalkyl-2-naphthols via one-pot three-component condensation reaction of 2-naphthol, arylaldehydes and acetonitrile (Ritter type reaction) in the presence of catalytic amount of trityl ch

Full text of DOI:10.1016/j.apcata.2010.07.057

Applied Catalysis A: General 386 (2010) 179–187
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Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Trityl chloride as an efficient organic catalyst for the synthesis of
1-amidoalkyl-2-naphtols in neutral media at room temperature
Ardeshir Khazaeia,∗, Mohammad Ali Zolfigola,∗∗, Ahmad Reza Moosavi-Zarea, Abdolkarim Zareb,
Abolfath Parhamib, Ali Khalafi-Nezhadc
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 6517838683, Iran
b Department of Chemistry, Payame Noor University (PNU), Iran
c Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 April 2010
Received in revised form 30 June 2010
Accepted 27 July 2010
Available online 6 August 2010
A highly efficient and simple procedure for the preparation of 1-amidoalkyl-2-naphthols via one-pot
three-component condensation reaction of 2-naphthol, arylaldehydes and acetonitrile (Ritter type reac-
tion) in the presence of catalytic amount of trityl chloride at room temperature is described. The reactions
proceed in high yields and in relatively short reaction times.
© 2010 Elsevier B.V. All rights reserved.
Keywords:
Trityl chloride
Organic catalyst
1-Amidoalkyl-2-naphthol
Multi-component reaction
Ritter type reaction
1. Introduction
[28], FeCl3·SiO2 [29], and triflic acid [30]. However, many of the
reported methods are associated with one or more of the follow-
1-Amidoalkyl-2-naphthol derivatives are significant as they
can be easily converted to 1-aminoalkyl-2-naphthols as an
important class of bioactive compounds, by amide hydrolysis
reaction. 1-Aminoalkyl-2-naphthols have been frequently applied
as hypotensive and bradycardiac agents [1–3]. 1-Amidoalkyl-
2-naphthols can be also converted to 1,3-oxazine derivatives
[4]. 1,3-Oxazines have potentially different biological activities
including antibiotic [5–7], antitumor [8–10], analgesic [11,12],
anticonvulsant [13], antipsychotic [14], antimalarial [15], antiang-
inal [16], antihypertensive [17], and antirheumatic properties
[18]. One-pot three-component condensation of 2-naphthol, ary-
laldehydes and amide derivatives or acetonitrile has been used
as a practical synthetic route toward 1-amidoalkyl-2-naphthols
[19–28]. Several Lewis and Brønsted acidic catalysts have been used
for this transformation, including Ce(SO4)2 [19], p-toluenesulfonic
acid [20], iodine [21], cation-exchanged resins [22], Fe(HSO4)3
[23], sulfamic acid/ultrasound [24], silica-supported perchloric
acid [25], NaHSO4·H2O [26], K5CoW12O40·3H2O [27], H3PW12O40
ing drawbacks: (i) low yield, (ii) long reaction time, (iii) harsh
reaction conditions, (iv) the use of toxic, corrosive, expensive or
non-reusable catalysts, (v) the use of large amount of catalyst,
(vi) application of large amount of acetonitrile (as reactant and
solvent), and (vii) because of the use of acidic catalysts in most
of the reported methods, application of aldehydes bearing basic
groups or acid-sensitive aldehydes in the reaction is not possible.
In addition, there are only very few methods for the synthesis of 1-
aminoalkyl-2-naphthols at room temperature or mild conditions
[21,24]. The preparation of these compounds via the condensation
of 2-naphthol, arylaldehydes and acetonitrile (Ritter type reaction)
has been also scarcely studied [19,23,25,26,29,30]. Thus, search for
finding an efficient, extremely mild and non-acidic catalyst for the
synthesis of 1-aminoalkyl-2-naphthols by Ritter type reaction is
still of practical importance.
The use of organic catalysts instead of inorganic Lewis and
Brønsted acidic catalysts have some advantages including (i) the
possibility to perform reactions for acid-sensitive substrates, (ii)
performing reactions in milder reaction conditions, (iii) selectivity,
and (iv) the substrates bearing basic functional groups or electron-
donating substituents prone to capture the acidic catalyst do not
affect reaction results [31–36]. While carbocations are Lewis acids,
their inherent instability has precluded up to now their use in
catalysis with decent turnover numbers. Nevertheless, recently, tri-
∗
Corresponding author. Fax: +98 811 8272404.
Corresponding author. Fax: +98 811 8272404.
∗∗
E-mail addresses: Khazaei 1326@yahoo.com (A. Khazaei), zolfi@basu.ac.ir,
mzolfigol@yahoo.com (M.A. Zolfigol).
0926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2010.07.057

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A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
Scheme 1. The synthesis of 1-amidoalkyl-2-naphthols.
Table 2
arylmethyl chlorides (Ar3CCl) have been successfully employed as
novel organic catalysts for the synthesis of bis(indolyl)methanes
[31] and N-sulfonyl imines [32] in which triarylmethyl cation has
acted as catalyst. Triarylmethyl chlorides are inexpensive and can
be obtained commercially or easily prepared by the known proce-
dure [37]. These compounds have been also extensively studied as
bulky protective groups for amino and primary hydroxyl functional
groups in multi-step organic synthesis [38]. Furthermore, triaryl-
methyl chlorides in combination with metal salts particularly SnCl2
have been used in a few organic transformations [39]. Nevertheless,
the use of these compounds in the absence of co-catalysts is really
attractive.
The condensation of 2-naphthol, 4-chlorobenzaldehyde and acetonitrile using dif-
ferent amounts of TrCl at room temperature.
Entry
Catalyst Amount (mol%)
Time (h)
Yielda (%)
1
2
3
4
5
5
7.5
10
12.5
15
4
3
1.25
1.25
1.25
82
90
94
94
94
a
Isolated yield.
To assess the efficiency and the scope of the organic catalyst
in the preparation of 1-amidoalkyl-2-naphthols, the condensa-
tion of 2-naphthol with various arylaldehydes and acetonitrile was
examined in the presence of TrCl at room temperatures. The cor-
responding results are displayed in Table 3. As it can be seen in
Table 3, the reactions were carried out efficiently within 0.75–4 h,
and the desired products were produced in high to excellent yields
(83–94%). Thus, TrCl is a highly efficient, general and mild organic
catalyst for the preparation of 1-amidoalkyl-2-naphthols. The
influence of electron-releasing substituents, electron-withdrawing
substituents and halogens on the aromatic ring of arylaldehydes on
the reaction results was investigated. As Table 3 indicates, electron-
releasing groups slightly decreased the yields and increased the
reaction times (entries 2–7); however, electron-withdrawing sub-
stituents and halogens had no significant effect on the yields, and
arylaldehydes bearing these substituents were reacted faster than
benzaldehyde (entries 8–15). It should be mentioned that when
the reaction was examined with 4-(dimethylamino)benzaldehyde,
the corresponding 1-amidoalkyl-2-naphthol (1g) was obtained in
86% yield, indicating that the amine function cannot affect the
efficiency of the reaction via irreversible complexation with the
catalyst (entry 7).
Interestingly, the condensation of 2-naphthol with 4-
(diethoxymethyl)benzaldehyde and acetonitrile was successfully
performed using trityl chloride and afforded two products 2a
and 2b (Scheme 2). When 1 equiv. of 2-naphthol and 1 equiv.
of the adehyde were reacted with 1.25 equiv. of acetonitrile in
the presence of TrCl (15 mol%), bis(1-amidoalkyl-2-naphthol) 2a
and 1-amidoalkyl-2-naphthol 2b were obtained in 25 and 39%,
respectively; however, the use of 2 equiv. of 2-naphthol, 1 equiv.
of 4-(diethoxymethyl)benzaldehyde and 2.5 equiv. of acetonitrile
gave compounds 2a and 2b in 76 and 18%, correspondingly. It
is worth noting that almost in none of the reported methods
Considering the above subjects, we wish to introduce trityl chlo-
ride as a highly efficient and homogeneous organic catalyst for the
synthesis of 1-amidoalkyl-2-naphthol derivatives by the one-pot
three-component condensation of 2-naphthol with aromatic alde-
hydes and acetonitrile under extremely mild conditions in neutral
media (Scheme 1).
2. Results and discussion
First of all, to optimize the reaction conditions, the reac-
tion of 2-naphthol (2 mmol), 4-chlorobenzaldehyde (2 mmol) and
acetonitrile (2.5 mmol) was selected as a model reaction, and
its behavior was studied in the presence of 10 mol% of trityl
chloride (TrCl), monomethoxytrityl chloride (Ph2(p-MeOC6H4)CCl,
MMTCl) and dimethoxytrityl chloride (Ph(p-MeOC6H4)2CCl) at
room temperature. The results are summarized in Table 1. As
it is shown in Table 1, higher yield and shorter reaction time
were obtained using trityl chloride. Furthermore, we calculated
turn over numbers (TON) and turn over frequencies (TOF) states
on the effectiveness of these catalysts for the synthesis of 1-
amidoalkyl-2-naphthols (Table 1). The TON and TOF values showed
that TrCl is more effective than MMTCl and DMTCl. Thus, TrCl
was chosen as catalyst for the synthesis of 1-amidoalkyl-2-
naphthols.
In another study, the condensation of 2-naphthol, 4-
chlorobenzaldehyde and acetonitrile was examined in the
presence of different quantities of trityl chloride at room temper-
ature (Table 2). As Table 2 indicates, the reasonable results were
obtained when the reaction was performed using 10 mol% of trityl
chloride (entry 3). No improvement in the reaction results was
observed by increasing the amount of trityl chloride to 15 mol%
(entries 4 and 5).
Table 1
Catalytic activity of different triarylmethyl chlorides on the reaction of 2-naphthol, 4-chlorobenzaldehyde and acetonitrile at room temperature.
Entry
Catalyst
Catalyst amount (mol%)
Time (h)
TONa
TOFb (h−1
)
Yieldc (%)
1
2
3
TrCl
MMTCl
DMTCl
10
10
10
1.25
3
5
9.4
8.5
5.7
7.52
2.83
1.14
94
85
57
a
Turn over number.
Turn over frequency.
Isolated yield.
b
c

A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
181
Table 3
The synthesis of 1-aminoalkyl-2-naphthols from 2-naphthol, aromatic aldehydes and acetonitrile using TrCl at room temperature.
Entry
Aldehyde
Product
Time (h)
1.75
Yielda (%)
Mp (◦C) (Lit.)
1
92
238–240 (241–243) [19]
2
2.5
89
220–222 (222–223) [23]
3
3
86
197–199 (200–202) [22]
4
3.25
87
183–185 (184–186) [23]
5
6
7
3.5
88
83
86
200–202 (203–205) [23]
232–234 (235–236) [23]
119–121 (123–125) [25]
4
3
8
9
1.75
93
94
246–248 (248–250) [28]
1.5
235–237 (236–237) [24]

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A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
Table 3 (Continued)
Entry
Aldehyde
Product
Time (h)
0.75
Yielda (%)
Mp (◦C) (Lit.)
10
11
12
92
177–179 (180–182) [23]
1.25
94
220–222 (224–227) [19]
1.5
91
197–199 (194–196) [24]
13
1
90
226–228 (227–229) [23]
14
1.25
92
201–204 (203–205) [24]
15
1
93
196–198 (198–199) [23]
a
Isolated yield.
for the preparation of 1-amidoalkyl-2-naphthol, the synthesis of
bis(1-amidoalkyl-2-naphthol)s has not been studied.
functional group in the reaction mixture was compared with those
in benzaldehyde as follows:
The condensation of 2-naphthol with bis-aldehydes (tereph-
thaldehyde) and acetonitrile was also rapidly performed using
TrCl at room temperature (Scheme 3). The use of 1 equiv.
of 2-naphthol, 1 equiv. of terephthalaldehyde and 1.25 equiv.
of acetonitrile in the reaction afforded bis(1-amidoalkyl-2-
naphthol) 2a and monomer 2c in 28 and 35%, respec-
tively. However, the condensation of 2 equiv. of 2-naphthol
with 1 equiv. of the aldehyde and 2.5 equiv. of acetonitrile
gave compounds 2a and 2c in 84 and 15%, correspond-
ingly.
In a proposed reaction mechanism, we suggest that aldehyde
and trityl chloride produce complexes of intermediates I and II in
a reversible reaction (Scheme 4) [31,32]. To prove the formation
of I and II, benzaldehyde was reacted with trityl chloride at room
temperature, and then IR, 1H and 13C NMR spectra of the aldehydic
IR (nujol): ꢀmax (cm−1
) of C O in benzaldehyde (1705)
decreased to 1700 in the reaction mixture.
1H NMR (300 MHz, CDCl3): ı (ppm) of the aldehydic hydrogen
(9.78) increased to 10.04 in the reaction mixture.
13C NMR (300 MHz, CDCl3): ı (ppm) of the carbonyl carbon
(191.8) increased to 195.2 in the reaction mixture.
These results confirm that intermediates I and II are present
in the reversible reaction media. Moreover, the cationic interme-
diates I and II have been introduced by Oikawa et al. for the first
time [40]. These complexes act as activated carbonyl compound
and then react with 2-naphthol providing III, which converts to IV
by proton transfer. Afterward, IV reacts with acetonitrile to obtain
V in a Ritter type reaction [19,26,29]. Hydrolysis of intermediate
V, by very few absorbed water from environment, produces VI,
and this intermediate together with previously produced Ph3COH

A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
183
Scheme 2. The condensation of 2-naphthol with 4-(diethoxymethyl)benzaldehyde and acetonitrile.
Scheme 3. The condensation of 2-naphthol with terephthaldehyde and acetonitrile.
afford VII, H2O and TrCl. This in situ produced H2O can convert
V to VI; thus, there is no need to absorb H2O from environment
except the few amount absorbed for starting the conversion of V
to VI. To verify this subject, the condensation of 2-naphthol with
4-chlorobenzaldehyde and acetonitrile was tested using TrCl in
the presence of different amounts of water at room temperature.
The results are summarized in Table 4. As Table 4 shows, incre-
ment the amount of water decreased the yield and enhanced the
reaction time. This can be attributed to the hydrolysis of TrCl to
TrOH in the presence of stoichiometric or larger amount of water.
It should be mentioned that because of high reactivity of inter-
mediate V, the gradually produced water in the reaction media
absorb very fast by this intermediate and cannot hydrolyze TrCl.
Therefore, the very few water in the reaction media absorbed from
environment accompanied with the water produced gradually in
the conversion of intermediate VI to VII is sufficient to hydrolyze
V to VI, and there is no need to add water to the reaction mixture.
Furthermore, in the papers cited in Refs. [19,23,25,26,29,30], the
reaction has been performed without addition of water. Finally,
intermediate VII converts to the corresponding 1-amidoalkyl-2-
naphthol by tautomerization [19,26,29]. The suggested mechanism
is confirmed based on Refs. [19,26,29,31,32,40], and also by the
fact that the catalyst was completely recovered unchanged and
triarylmethanol could not be identified after the completion of
the reaction as it could be observed on TLC by comparison with
pure authentic samples. In another study, to confirm that TrCl
cannot convert to TrOH and HCl by very few water presented in
the reaction medium from environment, and consequently HCl is
not the real catalyst of the process, the reaction of 2-naphthol, 4-
chlorobenzaldehyde and acetonitrile was examined in the presence
of the expected amount of HCl. In these conditions, the product
was obtained in 58% yield within 2.5 h, and two by-products were
produced as monitored by TLC. Moreover, the reaction was tested
using a base (pyridine) in which no progress in the reaction was
observed. The reaction was also examined in the presence of TrCl
together with pyridine wherein the reaction was carried out suc-
Table 4
The condensation of 2-naphthol (2 mmol) with 4-chlorobenzaldehyde (2 mmol) and
acetonitrile (2.5 mmol) using TrCl (0.2 mmol) in the presence of different amounts
of water.
Entry
Water amount (mmol)
Time (h)
Yielda (%)
1
2
3
4
5
6
7
–
0.5
1
2
4
1.25
1.25
1.5
1.75
2
94
91
85
74
60
38
17
10
20
3
8
a
Isolated yield.

184
A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
starting materials remained). Furthermore, the condensation of 2-
naphthol, 4-chlorobenzaldehyde and acetonitrile was checked in
the presence of only pyridinium chloride wherein the product was
produced in 36% yield after 12 h. These experiments confirm that
TrCl do not convert to TrOH and HCl in the reaction conditions; thus,
HCl is not the catalyst of our reaction, and TrCl really has catalyzed
the reaction.
To compare the applicability and the efficiency of trityl chloride
with the reported catalysts for the synthesis of 1-amidoalkyl-2-
naphthols via Ritter type reaction, we have tabulated turn over
frequency (TOF) of these catalysts to perform the condensation of
2-naphthol, 4-chlorobenzaldehyde and acetonitrile, in Table 5. As
it is shown in Table 5, trityl chloride is superior to the previously
reported catalysts in term of TOF.
3. Experimental
All chemicals were purchased from Merck or Fluka Chemical
Companies. The known products were identified by comparison of
their melting points and spectral data with those reported in the
literature. The 1H NMR (250 or 300 MHz) and 13C NMR (62.5 or
75 MHz) were run on a Bruker Avance DPX-250 FT-NMR spectrom-
eter (ı in ppm). Microanalyses were performed on a Perkin-Elmer
240-B microanalyzer. Melting points were recorded on a Büchi B-
545 apparatus in open capillary tubes.
3.1. General procedure for the synthesis of
1-amidoalkyl-2-naphthols 1a–1o
To a mixture of 2-naphthol (0.288 g, 2 mmol), aldehyde (2 mmol)
and acetonitrile (0.103 g, 2.5 mmol) in a test tube, was added TrCl
(0.056 g, 0.2 mmol), sealed with a stopper, and the resulting mix-
ture was stirred at room temperature for the times reported in
Table 3. Afterward, petroleum ether (20 mL) was added to the reac-
tion mixture, refluxed and stirred for 3 min, and filtered (trityl
chloride is soluble in petroleum ether; however, the products are
insoluble in this solvent). The filtrate containing the catalyst was
washed two times with 20 mL of 40% (w/v) solution of NaHSO3 in
H2O/EtOH (4/1) to extract the unreacted aldehyde dissolved in the
petroleum ether. The organic layer was separated and dried with
CaCl2; the solvent was evaporated to give pure recycled TrCl. The
resulting precipitate from previous step (crude product) was intro-
duced to a column chromatography on silica gel, and eluted with
EtOAc/n-hexane (1/1) to give pure 1-amidoalkyl-2-naphthols.
3.2. General procedure for the preparation of
bis(1-amidoalkyl-2-naphthol) 2a, and 1-amidoalkyl-2-naphthols
2b and 2c
Scheme 4. The proposed mechanism for the TrCl-catalyzed condensation of 2-
naphthol with aldehydes and acetonitrile.
To a mixture of 2-naphthol (0.576 g, 4 mmol), terephthalalde-
hyde (0.268 g, 2 mmol) and acetonitrile (0.206 g, 5 mmol) in a in a
test tube, was added TrCl (0.084 g, 0.3 mmol, 15 mol%), sealed with
a stopper, and the resulting mixture was stirred at room tempera-
ture for 1 h. Afterward, petroleum ether (30 mL) was added to the
reaction mixture, refluxed and stirred for 3 min, and filtered. The
filtrate was washed two times with 30 mL of 40% (w/v) solution of
NaHSO3 in H2O/EtOH (4/1). The organic layer was separated and
dried with CaCl2; the solvent was evaporated to give pure recycled
TrCl. Afterward, warm aqueous ethanol (15%, 30 mL) was added to
the resulting precipitate from previous step (crude products), and
stirred for 3 min (1-amidoalkyl-2-naphthol 2b is soluble in warm
aqueous ethanol; however, bis(1-amidoalkyl-2-naphthol) 2a is
insoluble in this solvent). During this time, the crude 1-amidoalkyl-
2-naphthol 2b was dissolved in the aqueous ethanol, and the pure
bis(1-amidoalkyl-2-naphthol) 2a was remained; thus, two prod-
ucts were easily separated by filtration. Then, the solvent of the
cessfully and the product was obtained in 94% within 1.25 h. In
these conditions, pyridine firstly absorbs one H+ from interme-
diate VI and produce pyridinium chloride. Afterward, pyridinium
chloride with TrOH (produced in the conversion of intermediate IV
to V) can form TrCl in a reversible reaction (Scheme 5) (to prove
this, in a separate reaction, pyridinium chloride was reacted with
TrOH at room temperature in which TrCl was obtained, and some
Scheme 5. The production of TrCl from pyridinium chloride and TrOH.

A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
185
Table 5
Comparison of the results of the reaction of 2-naphthol, 4-chlorobenzaldehyde and acetonitrile catalyzed by trityl chloride with those obtained by the reported catalysts.
Catalyst/conditions
Catalyst amount (mol%)
Time (h)
Yield (%)
TOFa (h−1
)
Ref.
b
TrCl/MeCN, r.t.
10
100
5
0.6
33.3
2.5
1.25
24
20
20
20
94
74
63
82
79
79
7.52
0.03
0.63
6.83
0.11
1.58
–
Ce(SO4)2/MeCN, reflux
Fe(HSO4)3/MeCN, reflux
HClO4/SiO2/MeCN, reflux
NaHSO4·H2O/MeCN, reflux
FeCl3·SiO2/MeCN, reflux
[19]
[23]
[25]
[26]
[29]
20
a
Turn over frequency.
Our work.
b
filtrate was evaporated and the crude 1-amidoalkyl-2-naphthol 2b
was purified by column chromatography on silica gel eluted with
EtOAc/n-hexane (1/1).
3.3.6. N-[(2-Hydroxynaphthalen-1-yl)(3,4-
dimethoxyphenyl)methyl]acetamide (1f)
Pale yellow solid; mp 232–234 ◦C (lit. [23] mp 235–236 ◦C); 1
H
NMR (300 MHz, DMSO-d6): ı (ppm) 2.08 (s, 3H), 3.67 (s, 3H), 6.74
(s, 3H), 6.74–6.82 (m, 2H), 7.94–8.42 (m, 7H), 7.96–8.08 (m, 2H),
9.75 (s, 1H); 13C NMR (75 MHz, DMSO-d6): ı (ppm) 22.6, 43.2, 56.0,
56.5, 112.9, 116.8, 117.5, 119.8, 121.3, 122.8, 124.4, 126.7, 127.6,
127.8, 128.4, 131.7, 135.3, 149.7, 151.6, 152.4, 168.7.
3.3. Selected spectral data of the products
3.3.1. N-[(2-Hydroxynaphthalen-1-yl)(phenyl)methyl]acetamide
(1a)
White solid; mp 238–240 ◦C (lit. [19] mp 241–243 ◦C); 1H NMR
(250 MHz, DMSO-d6): ı (ppm) 2.06 (s, 3H), 7.01–7.20 (m, 9H),
7.65–7.73 (m, 3H), 8.11 (d, J = 7.7 Hz, 1H), 9.69 (s, 1H); 13C NMR
(62.5 MHz, DMSO-d6): ı (ppm) 23.5, 41.3, 118.8, 120.2, 122.0, 123.9,
124.9, 125.7, 127.6, 128.1, 128.3, 128.5, 128.6, 134.2, 144.0, 152.6,
169.6; Anal. calcd. for C19H17NO2: C, 78.33; H, 5.88; N, 4.81. Found:
C, 78.52; H, 5.97; N, 4.93.
3.3.7. N-[(2-Hydroxynaphthalen-1-yl)(4-
dimethylaminophenyl)methyl]acetamide (1g)
Pale yellow solid; mp 119–121 ◦C (lit. [25] mp 123–125 ◦C); 1
H
NMR (300 MHz, DMSO-d6): ı (ppm) 1.97 (s, 3H), 3.02 (s, 6H), 6.63
(s, 1H), 6.70 (d, J = 8.4 Hz, 2H), 6.95–7.08 (m, 4H), 7.45–7.62 (m, 3H),
8.06 (d, J = 8.0 Hz, 1H), 8.43 (d, J = 8.3 Hz, 1H), 9.74 (s, 1H); 13C NMR
(75 MHz, DMSO-d6): ı (ppm) 23.2, 39.3, 42.9, 113.8, 117.4, 118.7,
121.6, 123.3, 126.9, 127.8, 128.1, 128.7, 130.0, 131.7, 133.8, 148.1,
152.3, 168.7.
3.3.2. N-[(2-Hydroxynaphthalen-1-yl)(4-
methylphenyl)methyl]acetamide (1b)
White solid; mp 220–222 ◦C (lit. [23] mp 222–223 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.08 (s, 3H), 2.29 (s, 3H), 7.08–7.19
(m, 6H), 7.32–7.38 (m, 2H), 7.63 (d, J = 8.4 Hz, 1H), 7.81–7.88 (m,
2H), 8.41 (d, J = 8.0 Hz, 1H), 9.78 (s, 1H); 13C NMR (75 MHz, DMSO-
d6): ı (ppm) 21.3, 24.7, 46.7, 117.1, 118.8, 121.9, 124.2, 125.6, 127.0,
128.6, 128.7, 129.2, 131.2, 136.1, 138.9, 145.0, 152.1, 169.3.
3.3.8. N-[(2-Hydroxynaphthalen-1-yl)(4-
nitroxyphenyl)methyl]acetamide (1h)
Yellow solid; mp 246–248 ◦C (lit. [28] mp 248–250 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.06 (s, 3H), 7.14–7.35 (m, 4H),
7.59–7.67 (m, 2H), 7.76 (d, J = 9.2, 2H), 7.95–8.06 (m, 3H), 8.52 (d,
J = 8.2 Hz, 1H), 9.86 (s, 1H); 13C NMR (75 MHz, DMSO-d6): ı (ppm)
23.1, 48.3, 118.2, 119.4, 121.3, 122.4, 123.1, 127.2, 128.4, 128.7,
129.8, 131.5, 133.6, 145.1, 149.3, 152.1, 168.9.
3.3.3. N-[(2-Hydroxynaphthalen-1-yl)(2-
methylphenyl)methyl]acetamide (1c)
White solid; mp 197–199 ◦C (lit. [22] mp 200–202 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 1.96 (s, 3H), 2.23 (s, 3H), 6.97–7.23
3.3.9. N-[(2-Hydroxynaphthalen-1-yl)(3-nitrophenyl)methyl]-
acetamide (1i)
Pale yellow solid; mp 235–237 ◦C (lit. [24] mp 236–237 ◦C); 1
H
(m, 7H), 7.61–7.78 (m, 4H), 8.39 (d, J = 8.0 Hz, 1H), 9.83 (s, 1H); 13
C
NMR (250 MHz, DMSO-d6): ı (ppm) 2.06 (s, 3H), 7.15–7.49 (m, 6H),
7.78–8.04 (m, 5H), 8.54 (d, J = 8.1 Hz, 1H), 10.12 (s, 1H); 13C NMR
(62.5 MHz, DMSO-d6): ı (ppm) 23.3, 48.1, 118.1, 118.7, 120.5, 122.3,
123.8, 125.7, 127.3, 128.4, 129.1, 129.6, 130.8, 133.1, 134.1, 144.5,
148.7, 152.9, 169.8; Anal. calcd. for C19H16N2O4: C, 67.85; H, 4.79;
N, 8.33. Found: C, 67.62; H, 4.68; N, 8.46.
NMR (75 MHz, DMSO-d6): ı (ppm) 20.8, 23.0, 44.1, 117.4, 118.6,
120.8, 123.5, 124.9, 126.3, 127.4, 128.1, 128.3, 128.7, 129.2, 130.8,
132.7, 135.2, 142.7, 152.7, 169.1.
3.3.4. N-[(2-Hydroxynaphthalen-1-yl)(4-
methoxyphenyl)methyl]acetamide (1d)
Pale yellow solid; mp 183–185 ◦C (lit. [23] mp 184–186 ◦C); 1
H
3.3.10. N-[(2-Hydroxynaphthalen-1-yl)(2-nitrophenyl)methyl]-
acetamide (1j)
NMR (300 MHz, DMSO-d6): ı (ppm) 2.09 (s, 3H), 3.63 (s, 3H), 6.68
(d, J = 8.0 Hz, 2H), 6.74 (s, 1H), 7.40–7.50 (m, 3H), 7.59 (t, J = 7.3 Hz,
2H), 7.78–7.85 (m, 2H), 8.39 (d, J = 8.2 Hz, 2H), 9.48 (s, 1H); 13C NMR
(75 MHz, DMSO-d6): ı (ppm) 22.4, 39.8, 55.0, 113.9, 117.6, 118.0,
122.8, 124.3, 126.8, 128.8, 128.9, 129.2, 131.1, 131.4, 137.4, 148.7,
157.9, 167.3.
Pale yellow solid; mp 177–179 ◦C (lit. [23] 180–182 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.03 (s, 3H), 7.06–7.38 (m, 5H),
7.70–7.81 (m, 4H), 7.90 (d, J = 8.2 Hz, 1H), 8.06 (d, J = 8.0 Hz, 1H),
8.49 (d, J = 8.1 Hz, 1H), 9.75 (s, 1H); 13C NMR (75 MHz, DMSO-d6):
ı (ppm) 22.8, 48.0, 117.1, 118.4, 121.3, 123.4, 124.5, 126.5, 127.3,
128.2, 128.5, 129.3, 132.2, 133.0, 133.9, 140.8, 148.6, 152.4, 169.2.
3.3.5. N-[(2-Hydroxynaphthalen-1-yl)(3-
methoxyphenyl)methyl]acetamide (1e)
3.3.11. N-[(2-Hydroxynaphthalen-1-yl)(4-
White solid; mp 200–202 ◦C (lit. [23] mp 203–205 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.05 (s, 3H), 3.60 (s, 3H), 6.71 (s, 1H),
6.97–7.36 (m, 7H), 7.70–7.78 (m, 2H), 8.02–8.11 (m, 2H), 9.81 (s,
1H); 13C NMR (75 MHz, DMSO-d6): ı (ppm) 23.2, 42.9, 56.2, 112.4,
114.1, 117.3, 118.2, 120.5, 122.6, 123.8, 127.0, 128.4, 128.6, 129.2,
131.2, 133.5, 142.3, 150.4, 159.8, 169.1.
chlorophenyl)methyl]acetamide (1k)
Pale yellow solid; mp 220–222 ◦C (lit. [19] 224–227 ◦C); 1H NMR
(250 MHz, DMSO-d6): ı (ppm) 2.07 (s, 3H), 7.06 (m, 2H), 7.14–7.24
(m, 5H), 7.68–7.77 (m, 3H), 7.98 (d, J = 7.4 Hz, 1H), 8.16 (d, J = 7.1 Hz,
1H), 9.90 (s, 1H); 13C NMR (62.5 MHz, DMSO-d6): ı (ppm) 23.2, 47.6,
118.8, 119.8, 122.1, 123.7, 125.8, 126.9, 127.4, 128.3, 128.6, 129.3,

186
A. Khazaei et al. / Applied Catalysis A: General 386 (2010) 179–187
129.9, 134.0, 143.4, 152.5, 169.8; Anal. calcd. for C19H16ClNO2: C,
70.05; H, 4.95; N, 4.30. Found: C, 70.25; H, 4.87; N, 4.24.
3.3.18. N-[(4-Formylphenyl)(2-hydroxynaphthalen-1-
yl)methyl]acetamide (2c)
Pale yellow solid; mp 237–240 ◦C; IR (KBr): 3390, 3207, 3057,
1700, 1628, 1607, 1278, 819 cm−1 1H NMR (300 MHz, DMSO-d6):
;
3.3.12. N-[(2-Hydroxynaphthalen-1-yl)(2-
chlorophenyl)methyl]acetamide (1l)
ı (ppm) 2.02 (s, 3H), 6.91–7.39 (m, 6H), 7.79–7.82 (m, 4H), 8.41 (d,
J = 6.6 Hz, 1H), 8.56 (d, J = 7.6 Hz, 1H), 9.93 (s, 1 H), 10.10 (s, 1 H); 13
C
White solid; mp 197–199 ◦C (lit. [24] 194–196 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.01 (s, 3H), 6.97–6.43 (m, 8H),
7.68–7.76 (m, 2H), 8.16–8.22 (m, 2H), 9.64 (s, 1H); 13C NMR
(75 MHz, DMSO-d6): ı (ppm) 22.6, 47.3, 118.0, 118.2, 123.5, 124.5,
126.9, 127.8, 127.9, 128.6, 129.1, 129.6, 130.2, 130.9, 131.8, 131.9,
143.6, 148.9, 169.7.
NMR (75 MHz, DMSO-d6): ı (ppm) 23.0, 48.4, 118.6, 118.8, 122.9,
123.5, 126.3, 127.1, 128.9, 129.1, 129.9, 130.1, 132.7, 134.9, 150.6,
153.7, 170.1, 193.1; MS: m/z = 319.2 (M+).
4. Conclusions
In conclusion, we have introduced a highly efficient and
homogenous organic catalyst for the one-pot three-component
Ritter type reaction of 2-naphthol, various arylaldehydes and ace-
tonitrile. The promising points for the presented methodology are
efficiency, generality, high yield, short reaction time, extremely
mild reaction conditions, cleaner reaction profile and simplicity
which makes it a useful and attractive process for the synthesis of
1-amidoalkyl-2-naphthoils as biologically interesting compounds.
3.3.13. N-[(2-Hydroxynaphthalen-1-yl)(4-
bromophenyl)methyl]acetamide (1m)
White solid; mp 226–228 ◦C (lit. [23] 227–229 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 1.98 (s, 3H), 6.98–7.34 (m, 8H),
7.61–7.67 (m, 2H), 7.86 (d, J = 10.1, 1H), 8.27 (d, J = 8.1 Hz, 1H), 9.74
(s, 1H); 13C NMR (75 MHz, DMSO-d6): ı (ppm) 23.7, 46.5, 117.8,
118.7, 121.2, 122.4, 123.8, 126.9, 128.4, 128.7, 129.3, 130.2, 131.0,
133.2, 139.8, 152.6, 168.4.
Acknowledgements
3.3.14. N-[(2-Hydroxynaphthalen-1-yl)(4-
The authors gratefully acknowledge partial support of this work
by the Research Affairs Office of Bu-Ali Sina University (Grant num-
ber 32-1716 entitled development of chemical methods, reagent
and molecules), Center of Excellence in Development of Chemical
Method (CEDCM), Hamedan, I.R Iran.
fluorophenyl)methyl]acetamide (1n)
White solid; mp 201–204 ◦C (lit. [24] 203–205 ◦C); 1H NMR
(300 MHz, DMSO-d6): ı (ppm) 2.05 (s, 3H), 7.11 (m, 2H), 7.18–7.35
(m, 5H), 7.65–7.78 (m, 4H), 8.46 (d, J = 7.9 Hz, 1H), 9.87 (s, 1H); 13
C
NMR (75 MHz, DMSO-d6): ı (ppm) 23.5, 47.1, 115.1, 117.9, 118.3,
121.4, 123.0, 126.1, 127.5, 128.0, 128.3, 128.9, 130.9, 137.1, 152.8,
160.1, 168.0.
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3.3.16.
N-[{4-[Acetylamino-(2-hydroxy-naphthalen-1-yl)-methyl]-
phenyl}-(2-hydroxy-naphthalen-1-yl)-methyl]acetamide (2a)
White solid; mp 277–279 ◦C; IR (KBr): 3402, 3192, 3059, 1644,
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;
(ppm) 2.01 (s, 6H), 7.17–7.39 (m, 12H), 7.77–7.93 (m, 6H), 8.53
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;
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111.8, 119.1, 119.6, 120.9, 122.7, 124.5, 126.2, 128.5, 129.1, 129.7,
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7.01; N, 3.62.
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