Triethylamine-bonded sulfonic acid ([Et3N-SO3H]Cl): A highly efficient and homogeneous catalyst for the condensation of 2-naphthol with arylaldehydes and amides (alkyl carbamates or thioamides)

Article abstract of DOI:10.1080/17415993.2012.690415

Ionic liquid triethylamine-bonded sulfonic acid ([Et₃N-SO ₃H]Cl, N,N-diethyl-N-sulfoethanammonium chloride) is utilized as a highly efficient, inexpensive and homogeneous catalyst to promote the following one-pot multi-component organic transformations under solvent-free conditions: (i) the condensation of 2-naphthol with arylaldehydes and amides leading to 1-amidoalkyl-2-naphthols, (ii) the reaction of 2- naphthol with aromatic aldehydes and alkyl carbamates to produce 1-carbamatoalkyl-2-naphthols, and (iii) the condensation between 2-naphthol, arylaldehydes and thioamides leading to 1-thioamidoalkyl-2- naphthols. High yields, short reaction times, efficiency, generality, clean process, simple methodology, low cost, easy work-up, ease of preparation of the catalyst, and environmentally benign conditions are some advantages of the protocols.

Full text of DOI:10.1080/17415993.2012.690415

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Triethylamine-bonded sulfonic acid
([Et 3N–SO 3H]Cl): a highly efficient
and homogeneous catalyst for the
condensation of 2-naphthol with
arylaldehydes and amides (alkyl
carbamates or thioamides)
Abdolkarim Zare a , Shayesteh Akbarzadeh a , Elmira Foroozani
a , Hamideh Kaveh a , Ahmad Reza Moosavi-Zare b , Alireza
Hasaninejad c , Mohammad Mokhlesi b , Mohammad Hassan Beyzavi
d & Mohammad Ali Zolfigol b
a Department of Chemistry, Payame Noor University, PO BOX
19395-4697, Tehran, Iran
b Faculty of Chemistry, Bu-Ali Sina University, Hamedan,
6517838683, Iran
c Department of Chemistry, Faculty of Sciences, Persian Gulf
University, Bushehr, 75169, Iran
d Institut für Chemie und Biochemie, Freie Universität Berlin,
Takustr. 3, 14195, Berlin, Germany
Published online: 11 Jun 2012.
To cite this article: Abdolkarim Zare , Shayesteh Akbarzadeh , Elmira Foroozani , Hamideh Kaveh ,
Ahmad Reza Moosavi-Zare , Alireza Hasaninejad , Mohammad Mokhlesi , Mohammad Hassan
Beyzavi & Mohammad Ali Zolfigol (2012) Triethylamine-bonded sulfonic acid ([Et 3N–SO 3H]Cl): a
highly efficient and homogeneous catalyst for the condensation of 2-naphthol with arylaldehydes
and amides (alkyl carbamates or thioamides), Journal of Sulfur Chemistry, 33:3, 259-272, DOI:
10.1080/17415993.2012.690415
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Journal of Sulfur Chemistry
Vol. 33, No. 3, June 2012, 259–272
Triethylamine-bonded sulfonic acid ([Et3N–SO3H]Cl): a highly
efficient and homogeneous catalyst for the condensation of
2-naphthol with arylaldehydes and amides (alkyl carbamates
or thioamides)
Abdolkarim Zarea*, Shayesteh Akbarzadeha, Elmira Foroozania, Hamideh Kaveha,
Ahmad Reza Moosavi-Zareb, Alireza Hasaninejadc, Mohammad Mokhlesib,
Mohammad Hassan Beyzavid and Mohammad Ali Zolfigolb
aDepartment of Chemistry, Payame Noor University, PO BOX 19395-4697, Tehran, Iran; bFaculty of Chem-
istry, Bu-Ali Sina University, Hamedan 6517838683, Iran; cDepartment of Chemistry, Faculty of Sciences,
Persian Gulf University, Bushehr 75169, Iran; dInstitut für Chemie und Biochemie, Freie Universität Berlin,
Takustr. 3, 14195 Berlin, Germany
(Received 6 March 2012; final version received 30 April 2012)
Ionic liquid triethylamine-bonded sulfonic acid ([Et3N–SO3H]Cl, N,N-diethyl-N-sulfoethanammonium
chloride) is utilized as a highly efficient, inexpensive and homogeneous catalyst to promote the following
one-pot multi-component organic transformations under solvent-free conditions: (i) the condensation of
2-naphthol with arylaldehydes and amides leading to 1-amidoalkyl-2-naphthols, (ii) the reaction of 2-
naphthol with aromatic aldehydes and alkyl carbamates to produce 1-carbamatoalkyl-2-naphthols, and
(iii) the condensation between 2-naphthol, arylaldehydes and thioamides leading to 1-thioamidoalkyl-2-
naphthols. High yields, short reaction times, efficiency, generality, clean process, simple methodology, low
cost, easy work-up, ease of preparation of the catalyst, and environmentally benign conditions are some
advantages of the protocols.
*Corresponding author. Email: abdolkarimzare@yahoo.com
ISSN 1741-5993 print/ISSN 1741-6000 online
© 2012 Taylor & Francis
http://dx.doi.org/10.1080/17415993.2012.690415
http://www.tandfonline.com

260 A. Zare et al.
Keywords: triethylamine-bonded sulfonic acid ([Et3N–SO3H]Cl, N,N-diethyl-N-sulfoethanammonium
chloride); ionic liquid; 1-amidoalkyl-2-naphthol; 1-carbamatoalkyl-2-naphthol; 1-thioamidoalkyl-2-
naphthol
1. Introduction
Ionic liquids (ILs) have received much attention in the last decade from chemists, due to their broad
range of potential uses (1–18). Moreover, they have various useful properties such as thermal
and chemical stability, nonflammable, nonvolatile under atmospheric conditions, recoverable,
eco-friendly nature, and wide liquid-state temperature range (1–4). The ability to design ILs
gave us an opportunity to generate ILs of special properties tailored to given reactions (1, 2).
Among the different kinds, Brønsted acidic ILs have attracted rising interest in the last few
years (11–18). These series of ILs have offered new possibilities for developing environmental
friendly acid catalysts for organic transformations, because of the advantages of combining liquid
and solid acids, their operational simplicity, efficacy, and selectivity coupled with their green
natures (11–18). Considering the high importance of Brønsted acidic ILs, more recently, we
have synthesized Brønsted acidic IL triethylamine-bonded sulfonic acid ([Et3N–SO3H]Cl, N,N-
diethyl-N-sulfoethanammonium chloride) by the reaction of triethylamine with chlorosulfonic
acid (Scheme 1) and introduced it as a highly efficient catalyst in organic synthesis (18). Herein,
we report that this IL can efficiently catalyze the syntheses of 1-amidoalkyl-2-naphthols, 1-
carbamatoalkyl-2-naphthols, and 1-thioamidoalkyl-2-naphthols. On the basis of the structure of
[Et3N–SO3H]Cl, we anticipate that it can act as an efficient catalyst in reactions which can benefit
from rate acceleration from acidic catalysts.
CH2Cl2
+
N
+
N
ClSO3H
Cl
SO3H
[Et3N-SO3H]Cl
Scheme 1. The synthesis of [Et3N–SO3H]Cl.
Multi-component reactions (MCRs) involve three or more compounds reacting in a single
event to form a product, which contains the essential parts of all the starting materials. MCRs are
welcome too in terms of economic and practical considerations. Furthermore, they contribute to
the requirements of an environmentally friendly process by reducing the number of synthetic steps,
energy consumption, and waste production. Therefore, in the last decade, research in academia
and industry has increasingly emphasized the use of MCRs as well as domino reaction sequences
for a broad range of products (19–25).
1-Amidoalkyl-2-naphthols, 1-carbamatoalkyl-2-naphthols, and 1-thioamidoalkyl-2-naphthols
are of importance because they can be easily converted to the important biologically active
compounds, 1-aminoalkyl-2-naphthols (26), by hydrolysis reactions. One of the most important
biologically active compounds containing a 1-aminoalkyl-2-naphthol moiety in its structure is
compound I which has been shown to have hypotensive and bradycardic activities (Figure 1)
(26). 1-Amidoalkyl-2-naphthol derivatives can also be converted to 1,3-oxazine derivatives
(II) (Figure 1) (27). 1,3-Oxazines have potentially different biological activities including
antibiotic (28), antitumor (29), analgesic (30), anticonvulsant (31), and antipsychotic (32)
properties.

Journal of Sulfur Chemistry 261
R
N
H
N
R
H
OH
O
(I)
(II)
Figure 1. The general structures of the bioactive compounds related to 1-amidoalkyl-2-naphthol derivatives.
Since 1-amidoalkyl (carbamatoalkyl or thioamidoalkyl)-2-naphthol derivatives have potentially
different biological activities (26–32), in recent years, much attention has been devoted to their
synthesis. These compounds have generally been synthesized by one-pot three-component con-
densations of 2-naphthol with arylaldehydes and amides (alkyl carbamates or thioamides) in the
presence of catalysts (15, 33–46). Nevertheless, the synthesis of 1-carbamatoalkyl-2-naphthols
(42–45), and especially 1-thioamidoalkyl-2-naphthol (46), has been scarcely studied in the lit-
erature. In general, although some catalysts for the synthesis of the title compounds are known,
newer catalysts continue to attract attention for their novelty, generality, unique features, and
effectiveness. Furthermore, most of the reported catalysts and methods for the synthesis of the
title compounds suffer from one or more of the following drawbacks: the use of expensive and
toxic catalysts, poor compliance with green chemistry protocols, the use of large amounts of
catalyst, low product yield, prolonged reaction time, the use of an additional energy (ultrasound
or microwave), and especially no generality (in most of the reported procedures, the synthesis of
one type of the title compounds has been achieved).
O
R
NH2
OH
NH
R = Methyl, Vinyl
Ar
O
R
1-Amidoalkyl-2-naphthols
(1-12)
O
O
OH
H3CO
NH2
[Et3N-SO3H]Cl (20 mol%)
Solvent-free, 110 °C
OH
+
Ar
H
Ar
NH
O
OCH3
1-Carbamatoalkyl-2-naphthols
(13-17)
S
H3C
NH2
OH
Ar
NH
CH3
S
1-Thioamidoalkyl-2-naphthols
(18-20)
Scheme 2. The synthesis of 1-amidoalkyl (carbamatoalkyl or thioamidoalkyl)-2-naphthols from
2-naphthol, arylaldehydes and amides, alkyl carbamates or thioamides using [Et3N–SO3H]Cl.

262 A. Zare et al.
In this paper, we report IL [Et3N–SO3H]Cl as a highly efficient, homogeneous, and inexpensive
catalyst to promote the following one-pot multi-component organic transformations at 110 ◦C
in the absence of solvent: (i) the condensation of 2-naphthol with arylaldehydes and amides
leading to 1-amidoalkyl-2-naphthols, (ii) the reaction of 2-naphthol with aromatic aldehydes and
alkyl carbamates to produce 1-carbamatoalkyl-2-naphthols, and (iii) the condensation between
2-naphthol, arylaldehydes, and thioamides leading to 1-thioamidoalkyl-2-naphthols (Scheme 2).
2. Results and discussion
The structure of [Et3N–SO3H]Cl was identified by 1H NMR, 13C NMR, and mass spectra. The
corresponding spectral data are reported in the Experimental section. The important peak in
1
the H NMR spectra of [Et3N–SO3H]Cl is related to the acidic hydrogen (SO3H) which was
observed at 7.43 ppm. To confirm that this peak (7.43) is really related to the hydrogen of SO3H
in [Et3N–SO3H]Cl, not to the hydrogen of ClSO3H (its unreacted starting material) or another
possible product formed from the reaction of NEt3 with ClSO3H (i.e. [Et3N–H][ClSO3]), we also
1
ran the H NMR spectra of ClSO3H as well as [Et3N–H]Cl in CDCl3 (the acidic hydrogen of
both [Et3N–H][ClSO3] and [Et3N–H]Cl is found on nitrogen. Since [Et3N–H][ClSO3] was not
available commercially in chemical companies catalogs, we used [Et3N–H]Cl instead of [Et3N–
H][ClSO3]). In these spectra, the peaks of the acidic hydrogen of [Et3N–SO3H]Cl, ClSO3H, and
[Et3N–H]Cl were observed at 7.43, 10.75, and 11.59 ppm, respectively. The difference between
the peaks of the acidic hydrogen in the compounds confirmed that the peak observed at 7.43 ppm
in the 1H NMR spectra of [Et3N–SO3H]Cl is correctly related to the hydrogen of the SO3H group
of this compound (18).
In another study, to prove that [Et3N–SO3H]Cl is the correct structure of the catalyst and is
responsible for the catalytic results, the condensation of 2-naphthol with 4-nitrobenzaldehyde
and acetamide was examined as a model reaction at 110 ◦C under solvent-free conditions in the
presence of 20 mol% of [Et3N–SO3H]Cl, NEt3, ClSO3H, and [Et3N–H]Cl as catalysts.The [Et3N–
H]Cl is used as a surrogate for [Et3N–H][ClSO3] since this latter compound is not commercially
available. This is justified because in both cases, it is the acidic proton on the ammonium cation
and not the counterion that is functioning as the catalyst. The results are displayed in Table 1. The
IL, [Et3N–SO3H]Cl, catalyzed the reaction resulting in excellent yields in a short reaction time.
In contrast, NEt3 gave low yields and ClSO3H and [Et3N–H]Cl afforded moderate yields of the
product but in relatively much longer reaction times. These results also confirmed that the catalyst
has been correctly synthesized, and its structure is [Et3N–SO3H]Cl, not [Et3N–H][ClSO3] (18).
It has been established that tertiary amine–sulfur trioxides (R3N+–SO3−) are produced by the
dropwise addition of 1 equiv. of chlorosulfonic acid to 2 equiv. of tertiary amines dissolved in
Table 1. The solvent-free condensation of 2-naphthol with
4-nitrobenzaldehyde and acetamide using NEt3, ClSO3H, and
[Et3N–H]Cl at 110 ◦C.
Entry
Catalyst
Time (min)
Yielda (%)
1
–
150
30
180
45
21
95
12
72
49
3
[Et3N–SO3H]Cl
NEt3
ClSO3H
[Et3N–H]Cl
4b
5
7
120
Notes: aIsolated yield.
bBecause of the low boiling point of NEt3, this reaction was carried out at
85 ◦C.

Journal of Sulfur Chemistry 263
dichloroethane at low temperature (Scheme 3) (47, 48). Under these conditions, the first equivalent
of tertiary amine adds to ClSO3H to displace chloride to form [R3N–SO3H]Cl, and the second
equivalentoftertiaryamine−actsasabasetoabstracttheacidichydrogentoformthetertiaryamine–
sulfur trioxides (R3N+–SO3 ) (47, 48). In our synthesis of [Et3N–SO3H]Cl, we added 1 equiv. of
triethylamine dropwise to 1 equiv. of chlorosulfonic acid at low temperature. Under these condi-
tions, there is always an excess of ClSO3H in the reaction mixture; thus, when [Et3N–SO3H]Cl
forms, there is no Et3N in the reaction media to abstract the acidic hydrogen to afford Et3N+–
SO−3 and Et3NHCl. We also demonstrated that 20 mol% of Et3N+–SO−3 is not as effective as our
catalyst, [R3N–SO3H]Cl, in the solvent-free reaction of 2-naphthol with 4-nitrobenzaldehyde and
acetamide at 110 ◦C and only gave a 24% yield of the product within 150 min. These studies
provide compelling evidence that the catalyst in our studies is [Et3N–SO3H]Cl (18).
R
R
R
+
2
+
ClSO3H
+
R3NHCl
R
N
R
SO3
R
N
Scheme 3. The preparation of R3N+–SO3− by the reaction of tertiary amines (2 equiv.) with
chlorosulfonic acid (1 equiv.).
Furthermore, more recently, Khazaei (14), Zolfigol et al. (15–17) and also Ghaffari Khaligh
(49) showed that when 1-methylimidazole (1 equiv.) or imidazole (2 equiv.) is reacted with chloro-
sulfonic acid (1 equiv.), the nitrogen atoms of 1-methylimidazole or imidazole act as nucleophiles
(not bases) and attack the sulfur of ClSO3H to give 3-methyl-1-sulfonic acid imidazolium chloride
([Msim]Cl) and 1,3-disulfonic acid imidazolium chloride ([Dsim]Cl), respectively (Scheme 4).
R = CH3
+
Cl
N
N
H3C
SO3H
ClSO3H
[Msim]Cl
N
N
R
R = H
+
Cl
N
N
HO3S
SO3H
[Dsim]Cl
Scheme 4. The nucleophilic reaction of 1-methylimidazole or imidazole with chlorosulfonic
acid.
To evaluate the efficacy of the catalyst in the synthesis of 1-amidoalkyl (carbamatoalkyl or
thioamidoalkyl)-2-naphthols, the one-pot multi-component condensation of 2-naphthol with 4-
nitrobenzaldehyde and acetamide was selected as a model reaction (Scheme 2), and its behavior
was studied in the presence of different amounts of [Et3N–SO3H]Cl under solvent-free conditions
in the range of 90–120 ◦C. The results are summarized in Table 2 and show that 20 mol% of
[Et3N–SO3H]Cl was sufficient to catalyze the reaction efficiently (Table 2, Entry 3). Moreover,
the optimal temperature for the reaction was 110 ◦C (Table 2, Entry 3). Increasing the amount of
the catalyst and the temperature did not improve the results (Table 2, Entries 4 and 7).
In the next step, the generality and the efficacy of [Et3N–SO3H]Cl, to catalyze the synthesis
of 1-amidoalkyl-2-naphthols, were explored by studying the reaction of 2-naphthol with dif-
ferent arylaldehydes and amides under the optimal reaction conditions (Table 3, compounds
1–12). It was observed that all arylaldehydes (bearing halogens and electron-withdrawing and

264 A. Zare et al.
Table 2. The condensation between 2-naphthol, 4-nitrobenzaldehyde, and acetamide using
different molar ratios of [Et3N–SO3H]Cl in the range of 90–120 ◦C.
Entry
Mol% of the catalyst
Temperature (◦C)
Time (min)
Yielda (%)
1
2
3
4
5
6
7
–
110
110
110
110
90
150
60
30
30
100
60
21
90
95
95
57
84
95
15
20
25
20
20
20
100
120
30
Note: aIsolated yield.
electron-releasing substituents on their aromatic rings) afforded the desired products in high to
excellent yields and in short reaction times; and also both amides (acetamide and acrylamide) gave
excellent results. Interestingly, the catalyst also efficiently promoted the reaction of 2-naphthol
with various aromatic aldehydes and methyl carbamate as well as thioacetamide to furnish
1-carbamatoalkyl-2-naphthols (Table 3, compounds 13–17) and 1-thioamidoalkyl-2-naphthols
(Table 3, compounds 18–20) in high to excellent yields and in short reaction times.
In another study, 2-naphthol (2 mmol) was reacted with 4-nitrobenzaldehyde (2 mmol) in the
presence of [Et3N–SO3H]Cl (20 mol%) without acetamide wherein 2-naphthol was completely
consumed, and some 4-nitrobenzaldehyde remained unreacted. In this reaction, about 30% of
14-(4-nitrophenyl)-14H-dibenzo[a, j]xanthene (18) and also two by-products were obtained.
3. Conclusion
In conclusion, we have introduced the IL [Et3N–SO3H]Cl as a new acidic catalyst for the prepa-
ration of 1-amidoalkyl (carbamatoalkyl or thioamidoalkyl)-2-naphthol derivatives via the one-pot
multi-component condensation of 2-naphthol with arylaldehydes and amides (alkyl carbamates
or thioamides) under solvent-free conditions. The described method has many advantages such
as generality, efficiency, simple work-up procedure, short reaction times, low cost, ease of prepa-
ration of the catalyst, clean production of the products in high yields, and good agreement with
green chemistry protocols.
4. Experimental
4.1. General
All chemicals were purchased from Merck or Fluka Chemical Companies. All known compounds
were identified by comparison of their melting points and NMR data with those reported in the
literature. The 1H NMR (250, 300, or 400 MHz) and 13C NMR (62.5, 75, or 100 MHz) were run
on a Bruker Avance DPX FT-NMR spectrometer (δ in ppm). Mass spectra were obtained with
Shimadzu GC-MS-QP 1100 EX model. Melting points were recorded on a Büchi B-545 apparatus
in open capillary tubes.
4.2. Preparation of [Et3N–SO3 H]Cl
A solution of triethylamine (0.50 g, 5 mmol) in CH2Cl2 (40 ml) was added dropwise to a stirring
solution of chlorosulfonic acid (0.58 g, 5 mmol) in dry CH2Cl2 (40 ml) over a period of 10 min

Journal of Sulfur Chemistry 265
Table 3. The solvent-free reaction of 2-naphthol with arylaldehydes and amide derivatives (methyl carbamate or
thioacetamide) catalyzed by [Et3N–SO3H]Cl at 110 ◦C.
Amide derivative
Aldehyde
Product
Time (min)
Yielda (%)
M.p. ◦C (Lit.)
OH
CHO
NH
40
94
237–239 (238–240) (15)
O
O
CH3
H3C
H3C
H3C
H3C
H3C
NH2
NH2
NH2
NH2
NH2
(1)
OH
NH
CH3
CHO
20
20
25
30
96
95
90
95
226–228 (226–228) (15)
221–223 (220–222) (15)
196–198 (197–199) (15)
245–247 (246–248) (15)
O
O
O
O
Br
O
(2)
Br
OH
NH
CH3
CHO
Cl
O
(3)
Cl
OH
CHO
Cl
NHCOCH3
Cl
(4)
OH
NH
CHO
NO2
O2N
O
CH3
(5)
OH
CHO
O2N
NH
15
30
96
93
182–184 (184–186) (33)
O
O
CH3
H3C
NH2
NO2
(6)
CHO
CH3
OH
NH
CH3
223–225 (224–226) (34)
(Continued)
O
H3C
O
H3C
NH2
(7)

266 A. Zare et al.
Table 3. Continued
Amide derivative
Aldehyde
Product
Time (min) Yielda (%)
M.p. ◦C (Lit.)
CHO
OH
NH
50
45
35
86
89
92
185–187 (184–186) (38)
O
H3CO
H3CO
O
CH3
H3C
NH2
OCH3
(8)
OH
CHO
NH
CH3
200–202 (200–202) (15)
O
O
H3C
NH2
OCH3
(9)
OH
NH
CHO
CHO
243–245 (247–249) (35)
CH2
O
O
H2C
NH2
(10)
OH
NH
30
30
15
10
94
91
93
96
217–219 (223–225) (36)
213–215 (214–216) (36)
220–222 (217–218) (43)
CH2
O
O2N
O
H2C
NH2
NO2
(11)
OH
NH
CHO
CH2
O
H3C
O
H2C
NH2
CH3
(12)
OH
NH
CHO
O
O
OCH3
H3CO
NH2
(13)
OH
NH
CHO
Br
171–173
O
Br
O
OCH3
H3CO
NH2
(14)
(Continued)

Journal of Sulfur Chemistry 267
Table 3. Continued
Amide derivative
Aldehyde
Product
Time (min)
Yielda (%)
M.p. ◦C (Lit.)
OH
Cl
CHO
Cl
NH
10
94
96
95
88
85
84
199–201 (196–198) (43)
O
O
OCH3
H3CO
H3CO
H3CO
NH2
NH2
NH2
(15)
OH
CHO
NO2
NH
10
10
30
30
25
203–205 (205–207) (36)
248–250 (253–255) (42)
190–193 (–) (46)
178–180
O
O2N
O2N
O
OCH3
(16)
OH
CHO
NH
OCH3
O
O
NO2
(17)
OH
NH
CH3
CHO
S
S
H3C
H3C
H3C
NH2
(18)
OH
NH
CHO
Br
S
Br
S
CH3
NH2
(19)
OH
CHO
O2N
NH
CH3
157–159
S
S
NH2
NO2
(20)
Note: aIsolated yield.
at 10 ◦C. Afterward, the reaction mixture was allowed to heat to room temperature (accompanied
with stirring) and stirred for another 4 h. The solvent was evaporated, and the liquid residue was
triturated with t-butylmethyl ether (3 × 10 ml) and dried under powerful vacuum at 90 ◦C to give
[Et3N–SO3H]Cl as a viscous pale yellow oil in 93% yield (18).

268 A. Zare et al.
4.2.1. N,N-Diethyl-N-sulfoethanammonium chloride ([Et3N–SO3H]Cl)
1H NMR (400 MHz, CDCl3) δ = 1.41 (t, J = 7.2 Hz, 9H), 3.17 (q, J = 7.2 Hz, 6H), 7.43 (br,
1H). 13C NMR (100 MHz, CDCl3) δ = 8.9, 47.0. MS (m/z): 218 (M+ + 1), 217 (M+).
4.3. General procedure for the synthesis of 1-amidoalkyl (carbamatoalkyl or
thioamidoalkyl)-2-naphthols
To a well-ground mixture of 2-naphthol (0.288 g, 2 mmol), aldehyde (2 mmol), and amide (alkyl
carbamate or thioamide) (2.4 mmol) in a test tube was added [Et3N–SO3H]Cl (0.087 g, 0.4 mmol),
and the resulting mixture was firstly stirred magnetically and after solidification of the reaction
mixture with a small rod at 110 ◦C for the times reported in Table 3. Afterward, the reaction
mixture was cooled to room temperature, H2O (8 ml) was added to it, stirred for 3 min, and
filtered. The solid residue was recrystallized from EtOH (95%) to give the pure product.
4.3.1. N-[(2-Hydroxynaphthalen-1-yl)(phenyl)methyl]acetamide (1)
1H NMR (250 MHz, DMSO-d6) δ = 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) δ = 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.
4.3.2. N-[(2-Hydroxynaphthalen-1-yl)(4-bromorophenyl)methyl]acetamide (2)
1H NMR (300 MHz, DMSO-d6) δ = 1.98 (s, 3H), 6.98–7.34 (m, 8H), 7.61–7.67 (m, 2H), 7.86
(d, J = 10.1 Hz, 1H), 8.27 (d, J = 8.1 Hz, 1H), 9.74 (s, 1H). 13C NMR (75 MHz, DMSO-d6)
δ = 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.
4.3.3. N-[(2-Hydroxynaphthalen-1-yl)(4-chlorophenyl)methyl]acetamide (3)
1H NMR (250 MHz, DMSO-d6) δ = 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) δ = 23.2, 47.6, 118.8, 119.8, 122.1, 123.7, 125.8, 126.9, 127.4, 128.3, 128.6, 129.3,
129.9, 134.0, 143.4, 152.5, 169.8.
4.3.4. N-[(2-Hydroxynaphthalen-1-yl)(2-chlorophenyl)methyl]acetamide (4)
1H NMR (300 MHz, DMSO-d6) δ = 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) δ = 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.
4.3.5. N-[(2-Hydroxynaphthalen-1-yl)(4-nitrophenyl)methyl]acetamide (5)
1H NMR (400 MHz, DMSO-d6) δ = 2.04 (s, 3H), 7.21–7.32 (m, 3H), 7.43 (t, J = 7.6 Hz, 1H),
7.54–7.61 (m, 2H), 7.82–7.91 (m, 3H), 8.07 (m, 2H), 8.66 (d, J = 8.0 Hz, 1H), 10.16 (s, 1H).
13C NMR (100 MHz, DMSO-d6) δ = 23.0, 48.0, 118.9, 120.9, 121.7, 123.1, 127.2, 128.9, 129.2,
130.0, 130.4, 132.6, 133.3, 145.9, 148.2, 153.8, 170.2.

Journal of Sulfur Chemistry 269
4.3.6. N-[(2-Hydroxynaphthalen-1-yl)(3-nitrophenyl)methyl]acetamide (6)
1H NMR (250 MHz, DMSO-d6) δ = 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) δ = 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.
4.3.7. N-[(2-Hydroxynaphthalen-1-yl)(p-tolyl)methyl]acetamide (7)
1H NMR (400 MHz, DMSO-d6) δ = 2.0 (s, 3H), 2.24 (s, 3H), 7.05–7.10 (m, 4H), 7.14 (d, J =
8.4 Hz, 1H), 7.24–7.29 (m, 2H), 7.37 (t, J = 7.2 Hz, 1H), 7.76–7.82 (m, 2H), 7.87 (s, 1H), 8.45
(d, J = 8.4 Hz, 1H), 10.0 (s, 1H). 13C NMR (100 MHz, DMSO-d6) δ = 21.0, 23.1, 48.1, 118.9,
119.5, 122.8, 123.8, 126.4, 126.7, 129.0, 129.1, 129.6, 132.8, 135.5, 140.0, 153.5, 169.6.
4.3.8. N-[(2-Hydroxynaphthalen-1-yl)(4-methoxyphenyl)methyl]acetamide (8)
1H NMR (300 MHz, DMSO-d6) δ = 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) δ = 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.
4.3.9. N-[(2-Hydroxynaphthalen-1-yl)(3-methoxyphenyl)methyl]acetamide (9)
1H NMR (300 MHz, DMSO-d6) δ = 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) δ = 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.
4.3.10. N-[(2-Hydroxynaphthalen-1-yl)(phenyl)methyl]acrylamide (10)
1H NMR (300 MHz, DMSO-d6) δ = 5.59 (1H, d, J = 10.2 Hz), 6.12 (1H, d, J = 17.1 Hz), 6.59
(dd, 1H, J = 9.9, 16.5 Hz), 7.14–7.35 (m, 8H), 7.74–7.87 (m, 3H), 8.69 (d, J = 7.8, 1H), 10.01 (s,
1H). 13C NMR (75 MHz, DMSO-d6) δ = 48.5, 118.9, 119.0, 122.8, 123.1, 123.7, 126.1, 126.6,
126.8, 128.5, 128.9, 129.0, 129.8, 132.3, 132.8, 142.7, 153.7, 164.9.
4.3.11. N-[(2-Hydroxynaphthalen-1-yl)(4-nitrophenyl)methyl]acrylamide (11)
1H NMR (400 MHz, DMSO-d6) δ = 5.66 (d, J = 10.4 Hz, 1H), 6.22 (d, J = 16.8 Hz, 1H), 6.67
(dd, J = 10.4, 17.2 Hz, 1H), 7.22–7.33 (m, 3H), 7.44 (d, J = 8.8 Hz, 3H), 7.83–7.86 (m, 3H),
8.18 (d, J = 8.8 Hz, 2H), 8.89 (d, J = 8.0 Hz, 1H), 10.17 (s, 1H). 13C NMR (100 MHz, DMSO-
d6) δ = 48.5, 118.0, 118.9, 123.1, 123.3, 123.7, 126.6, 127.2, 127.6, 128.9, 129.1, 130.4, 131.8,
132.7, 146.4, 151.2, 153.9, 165.3.
4.3.12. N-[(2-Hydroxynaphthalen-1-yl)(p-tolyl)methyl]acrylamide (12)
1H NMR (300 MHz, DMSO-d6) δ = 2.21 (s, 3H), 5.59 (d, J = 9.6 Hz, 1H), 6.12 (d, J = 16.8 Hz,
1H), 6.59 (dd, J = 15.9, 10.2 Hz, 1H), 7.04–7.35 (m, 8H), 7.74–7.85 (m, 3H), 8.68 (d, J = 7.5 Hz,
1H), 10.00 (s, 1H). 13C NMR (75 MHz, DMSO-d6) δ = 21.0, 49.5, 118.9, 119.1, 122.8, 123.8,
126.0, 126.5, 126.8, 128.9, 129.3, 131.8, 132.3, 135.7, 139.6, 153.7, 164.9.

270 A. Zare et al.
4.3.13. Methyl (2-hydroxynaphthalen-1-yl)(phenyl)methylcarbamate (13)
1H NMR (400 MHz, DMSO-d6) δ = 3.59 (s, 3H), 6.90 (d, J = 8.8 Hz, 1H), 7.17–7.19 (m, 1H),
7.24–7.30 (m, 6H), 7.41 (t, J = 7.6 Hz, 1H), 7.68 (d, J = 5.6 Hz, 1H), 7.77–7.83 (m, 2H), 7.95
(d, J = 8.0 Hz, 1H), 10.14 (s, 1H). 13C NMR (100 MHz, DMSO-d6) δ = 50.8, 52.1, 118.9, 119.3,
123.0, 126.5, 126.8, 127.0, 128.5, 128.8, 129.0, 129.7, 132.5, 142.8, 153.3, 157.0.
4.3.14. Methyl (4-bromophenyl)(2-hydroxynaphthalen-1-yl)methylcarbamate (14)
1H NMR (400 MHz, DMSO-d6) δ = 3.59 (s, 3H), 6.85 (d, J = 8.8 Hz, 1H), 7.19 (d, J = 8.0 Hz,
1H), 7.23–7.31 (m, 2H), 7.41 (t, J = 8.0 Hz, 2H), 7.47 (d, J = 8.4 Hz, 2H), 7.72 (d, J = 5.2 Hz,
1H), 7.78–7.83 (m, 2H), 7.91 (d, J = 7.2 Hz, 1H), 10.18 (s, 1H). 13C NMR (100 MHz, DMSO-d6)
δ = 50.4, 52.1, 118.8, 118.9, 119.9, 123.0, 127.1, 128.7, 128.8, 129.0, 130.0, 131.4, 132.4, 142.4,
153.4, 157.1; MS (m/z): 386 (M+).
4.3.15. Methyl (3-chlorophenyl)(2-hydroxynaphthalen-1-yl)methylcarbamate (15)
1H NMR (400 MHz, DMSO-d6) δ = 3.59 (s, 3H), 6.87 (d, J = 8.8 Hz, 1H), 7.16 (d, J = 7.2 Hz,
1H), 7.21–7.32 (m, 5H), 7.42 (t, J = 8.0 Hz, 1H), 7.77–7.84 (m, 3H), 7.93 (d, J = 8.4 Hz, 1H),
10.2 (s, 1H). 13C NMR (100 MHz, DMSO-d6) δ = 50.4, 52.2, 118.7, 118.8, 123.0, 123.3, 125.2,
126.2, 126.8, 127.1, 128.8, 129.1, 130.1, 130.5, 132.4, 133.3, 145.5, 153.4, 157.1.
4.3.16. Methyl (2-hydroxynaphthalen-1-yl)(4-nitrophenyl)methylcarbamate (16)
1H NMR (400 MHz, DMSO-d6) δ = 3.62 (s, 3H), 6.99 (d, J = 8.4 Hz, 1H), 7.24–7.32 (m, 2H),
7.53 (t, J = 8.0 Hz, 1H), 7.50 (d, J = 8.8 Hz, 2H), 7.83 (t, J = 8.4 Hz, 2H), 7.88 (s, 1H), 7.93
(d, J = 6.4 Hz, 1H), 8.16 (d, J = 8.8 Hz, 2H), 10.25 (s, 1H). 13C NMR (100 MHz, DMSO-d6)
δ = 50.7, 52.2, 118.4, 118.8, 123.1, 123.2, 123.8, 127.3, 127.6, 128.8, 129.1, 130.3, 132.4, 146.5,
151.1, 153.6, 157.2.
4.3.17. Methyl (2-hydroxynaphthalen-1-yl)(3-nitrophenyl)methylcarbamate (17)
1H NMR (400 MHz, DMSO-d6) δ = 3.62 (s, 3H), 7.00 (d, J = 8.4 Hz, 1H), 7.24–7.32 (m, 2H),
7.44 (t, J = 7.2 Hz, 1H), 7.55 (t, J = 8.0 Hz, 1H), 7.65 (d, J = 8.0 Hz, 1H), 7.83 (t, J = 6.0 Hz,
2H), 7.94 (d, J = 8.0 Hz, 1H), 7.99 (d, J = 8.0 Hz, 1H), 8.07 (d, J = 8.0 Hz, 1H), 8.15 (s, 1H),
10.29 (s, 1H). 13C NMR (100 MHz, DMSO-d6) δ = 50.5, 52.2, 118.3, 118.9, 120.9, 121.6, 121.9,
123.1, 127.3, 128.8, 129.1, 130.4, 132.4, 133.3, 133.9, 145.5, 148.2, 153.6, 157.2.
4.3.18. N-[(2-Hydroxynaphthalen-1-yl)(phenyl)methyl]thioacetamide (18)
1H NMR (300 MHz, DMSO-d6) δ = 2.54 (s, 3H), 7.11–7.28 (m, 8H), 7.40 (t, J = 8.1 Hz, 1H),
7.79 (t, J = 8.7 Hz, 3H), 7.96 (d, J = 8.7 Hz, 1H), 10.39 (s, 1H). 13C NMR (75 MHz, DMSO-d6)
δ = 33.5, 55.9, 117.4, 119.0, 122.9, 123.3, 126.5, 126.9, 127.1, 128.4, 128.7, 129.0, 130.1, 133.2,
140.8, 154.2, 200.0. MS (m/z): 307 (M+).
4.3.19. N-[(4-Bromophenyl)(2-hydroxynaphthalen-1-yl)methyl]thioacetamide (19)
1H NMR (400 MHz, DMSO-d6) δ = 2.59 (s, 3H), 7.09 (d, J = 8.4 Hz, 2H), 7.25 (d, J = 8.0 Hz,
1H), 7.31 (t, J = 7.2 Hz, 1H), 7.43–7.49 (m, 3H), 7.78–7.85 (m, 3H), 7.99 (d, J = 8.8 Hz, 1H),

Journal of Sulfur Chemistry 271
10.20 (s, 1H), 10.40 (d, J = 8.0 Hz, 1H). 13C NMR (100 MHz, DMSO-d6) δ = 33.4, 55.3, 117.0,
118.9, 120.0, 123.1, 123.2, 127.2, 128.7, 129.1, 130.4, 131.3, 131.4, 133.0, 140.4, 154.2, 200.6.
MS (m/z): 386 (M+).
4.3.20. N-[(2-Hydroxynaphthalen-1-yl)(3-nitrophenyl)methyl]thioacetamide (20)
1H NMR (400 MHz, DMSO-d6) δ = 2.63 (s, 3H), 7.28 (d, J = 12.0 Hz, 1H), 7.31 (t, J = 7.6 Hz,
1H), 7.49 (t, J = 7.6 Hz, 1H), 7.58 (d, J = 5.2 Hz, 2H), 7.81–7.90 (m, 3H), 7.98 (s, 1H), 8.03 (d,
J = 8.4 Hz, 1H), 8.08–8.11 (m, 1H), 10.3 (s, 1H), 10.56 (d, J = 8.0 Hz, 1H). 13C NMR (100 MHz,
DMSO-d6) δ = 33.3, 35.3, 116.5, 118.9, 121.1, 122.0, 122.9, 123.2, 127.5, 128.7, 129.2, 130.1,
130.9, 133.0, 133.5, 143.5, 148.2, 145.3. 201.3. MS (m/z): 352 (M+).
Acknowledgements
The authors thank Payame Noor University and Bu-Ali Sina University Research Councils for the financial support of
this work.
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