Piper-betle-shaped nano-S-catalyzed synthesis of 1-amidoalkyl-2-naphthols under solvent-free reaction condition: A greener nanoparticle-catalyzed organic synthesis enhancement approach

Article abstract of DOI:10.1021/jo302682k

Nano-S prepared by an annealing process showed excellent catalytic activity for the synthesis of 1-amidoalkyl-2-naphthols under solvent-free reaction condition at 50 C. The catalyst could be reused up to the fifth cycle without loss in its action. The gre

Full text of DOI:10.1021/jo302682k

Note
pubs.acs.org/joc
Piper-Betle-Shaped Nano-S-Catalyzed Synthesis of 1‑Amidoalkyl-2-
naphthols under Solvent-Free Reaction Condition: A Greener
“Nanoparticle-Catalyzed Organic Synthesis Enhancement” Approach
Vijay K. Das, Madhurjya Borah, and Ashim J. Thakur*
Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, India
S
* Supporting Information
ABSTRACT: Nano-S prepared by an annealing process showed excellent
catalytic activity for the synthesis of 1-amidoalkyl-2-naphthols under solvent-free
reaction condition at 50 °C. The catalyst could be reused up to the fifth cycle
without loss in its action. The green-ness of the present protocol was also
measured using green metrics drawing its superiority.
ecently, nanotechnology is mastering intricacies for the
synthesis and application of interesting nanomaterials.1
Scheme 1. Synthesis of 1-Amidoalkyl-2-naphthols
R
Nanoparticles have evoked tremendous awareness as nano-
catalysts,2 bridging the homogeneous and heterogeneous
catalysis.3 Hence, nanocatalysis should proffer the prospects
for the synthesis of challenging compounds.4
The synthesis of sulfur in bulk or micro- or nanoform has
been pursued significantly due to its remarkable applications5 in
sulfur nanocomposites,6 modified carbon nanostructures,7 and
sulfur nanowires,8 etc. There are some reports for the
preparation and properties of sulfur nanoparticles.9
The preparation of nano-S was accomplished by annealing
elemental sulfur, which in turn was achieved by catalytic
conversion of H2S.18 To characterize the sulfur nanoparticles
synthesized at 120 and 180 °C, the EDX analysis was
performed to find the elemental composition. EDX confirmed
the presence of sulfur element only (Figure 1a). Both atomic
and weight percent for pure nano-S was found to be 100%.
SEM image (Figure 1b) of pure nano-S explored its sheet-like
structure that might be due to the stronger intermolecular
forces of attraction among the sulfur molecules.
The multicomponent reactions10 (MCRs) are promising
constructive sources for devising large molecules with economic
viability.11 In the premise of green chemistry,12 MCR under
solvent-free reaction condition (SFRC)13a,b are fascinating
since it involves the best reaction medium with “no
medium”.13c The synthesis of amidoalkyl naphthols14 is
important as the 1,3-amino-oxygenated moiety is ubiquitous
to a variety of biologically significant compounds.15
The TGA curve (Figure 1c) indicated the thermal stability
having a two-step pattern of weight loss within 180−290 °C.
The first weight loss (<180 °C) is attributed to the evaporation
of physically absorbed water, and the second weight loss at 290
°C is accompanied by the active liberation of H2S (Figure 1c).
The X-ray diffraction patterns (Figure 2) for (a) bulk-S, (b)
nano-S8 synthesized at 120 °C and (c) at 180 °C revealed that
the samples (a), (b), and (c) showed peaks corresponding to
(222), (026), (117), (313), (044), (062), (066), (357), and
(551) planes, indicating the presence of cubic orthorhombic
There are numerous approaches described in the literature
for the synthesis of 1-amidoalkyl-2-naphthols. These proto-
cols16 suffer from shortcomings such as large waste production,
higher reaction temperature, prolonged reaction time, low
yields, harsh conditions, undesirable byproducts, toxicity, low
recovery, and reusability of the catalyst. Therefore, to overcome
those drawbacks and in our continual interest in the growth of
“NOSE” (nanoparticle-catalyzed organic synthesis enhance-
ment) chemistry,17 we herein report a convenient protocol for
novel sulfur nanoparticle-catalyzed synthesis of 1-amidoalkyl-2-
naphthols under SFRC at 50 °C (Scheme 1). To the best of our
knowledge, nano-S-catalyzed synthesis of 1-amidoalkyl-2-
naphthols is not yet reported.
Received: January 3, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo302682k | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
Figure 1. (a) EDX analysis, (b) SEM image, and (c) TGA curve of pure nano-S.
a
Table 1. Optimization of Reaction Condition
b
entry
catalyst
none
solvent
T (°C)
t (h)
yield (%)
h
c
1
2
SFRC
SFRC
SFRC
SFRC
SFRC
SFRC
SFRC
SFRC
SFRC
EtOAc
MeOH
EtOH
THF
rt
3
16
16
16
5
NR
c
none
50
70
120
50
50
50
50
NR
c
3
none
NR
c
4
none
NR
d
e
5
nano-MgO
32
25
j
6
nano-Al2O3
5
f
7
nano-TiO2
6
g
k
8
nano-S8
30
98
52
48
24
26
44
j
g
i
k
9
nano-S8
60
30
g
10
11
12
13
14
15
16
17
18
19
nano-S8
50
50
50
50
50
50
50
50
50
50
6
7
g
nano-S8
g
nano-S8
7
g
nano-S8
9
g
nano-S8
toluene
H2O
5
Figure 2. XRD pattern of (a) pure bulk sulfur, (b) nano-sulfur
annealed at 120 °C and (c) nano-sulfur annealed at 180 °C.
g
nano-S8
12
8
12
17
17
15
17
pyridine
imidazole
Et3N
SFRC
SFRC
SFRC
SFRC
8
face-centered S8 (i.e., α-form) with face-centered lattice sites
(JCPDS PDF #78-1889). The sharp XRD peaks of bulk sulfur
(Figure 2a) were broadened on annealing to 120 and 180 °C
(Figure 2b,c), which confirmed the transformation into the
nanoform.
The crystallite sizes were found to lie between 13.8 and 25.6
nm in (b) and 7.3−5.4 nm in (c) calculated from the X-ray line
broadening by applying the full width at half-maximum (fwhm)
of characteristic peaks (222) and (117) to the Scherrer
equation. These sizes are consistent with those measured from
the TEM images, indicating the single crystal structure of
nanoparticles.
8
PPh3
8
a
Reaction condition: benzaldehyde (0.3 mL, 3 mmol), urea (0.180 g, 3
mmol), naphthol (0.432 g, 3 mmol), SFRC, or solvent (5 mL).
b
c
Isolated yields. No reaction was observed, 3.5 mol % of catalyst was
d
e
f
g
used. Particle sizes. 17.4−16.4 nm. 37.4−39.7 nm. <80 nm. 5.2−
18.3 nm. Grinded. Ultrasound. Trace. Minute.
h
i
j
k
2) among 2-naphthol 1, urea 2, and benzaldehyde 3 at room
temperature under neat condition by grinding with mortar and
Scheme 2. Model Reaction
High-resolution TEM (Figure 3) showed that the majority of
isolated particles had piper betle shape and a very few were of
pestle, but the reaction did not proceed (entry 1). Stirring the
reaction mixture at 50 °C/70 °C/120 °C aerobically (16 h)
also could not form any product (entries 2−4). These negative
results indicated the necessity of a catalyst. Next, we
investigated the reaction by using nanocatalysts (3.5 mol %)
under SFRC at 50 °C (entries 5−9). To our surprise, the
mentioned nanocatalysts furnished the products in trace to
poor yields, but nano-sized S8 showed outstanding activity in
the formation of desired product 4 (entry 8) in excellent yields
within much shorter time. The reaction was very clean with no
side product formation.
Figure 3. TEM micrographs of nano-S at (a) 25 nm and (b) 50 nm
scale.
spherical structure with an average diameter of 5.2 nm (Figure
3a) and 18.3 nm (Figure 3b).
With the idea of developing a green procedure with almost
no waste produced for the synthesis of amidoalkyl naphthol
derivatives, the optimization of the reaction condition (Table
1) was performed by considering the model reaction (Scheme
In order to check the effect of solvents (if any) in the
reaction, several solvents were screened. The reactions were
sluggish and gave poor yield with longer reaction time and
B
dx.doi.org/10.1021/jo302682k | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
tiresome catalyst isolation in the presence of solvents (entries
10−15). This may be attributed to the aggregation of sulfur
nanoparticles which might reduce its surface area and block the
active sites. Notably, the bulk basic catalysts were not effective
in the reaction (entries 16−19).
We also examined the influence of catalyst loading in the
model reaction (Scheme 2). The results are summarized in
Table S1 and graphically in Figure S1 (Supporting
Information), which indicated that the catalytic efficiency of
nano-S8 increased from 1 to 3 mol % and showed the maximum
efficiency at 3.5 mol % loading. Increasing catalyst loading,
keeping the reaction time constant (30 min), did not improve
the yield (entries 8−12).
akin to it has been previously reported with the sulfur-
containing catalysts.16d,23
The data assembled from the catalyst recyclability test
(Supporting Information, Table S2) delineated that the nano-S
was equally active in the synthesis of 4 (Scheme 2) from fresh
up to the fifth cycle, and after that, its yield slightly decreased
with a bit longer reaction time. The TONs (turnover numbers)
were also maintained from fresh up to the fifth cycle and then
dropped off to some extent.
The XRD patterns of the reused nano-S after the third and
fifth run were compared with the fresh one (Supporting
Information, Figure S3a). The reused nano-S after the third run
demonstrated unchanged morphology, but after the fifth run, it
showed a slight diminution in the intensity of the highest peak
(222) and an increase in the intensity of the (551) peak. It
might be due to the dislocation in the crystal planes17 during
the consecutive cycles.
To generalize the reaction, various benzaldehyde derivatives
were tested with naphthol and urea/acetamide under the
standardized condition, and the outcomes are summarized in
Table 2. Vaghei et al. reported the synthesis of (4-
The TEM micrograph (Supporting Information, Figure S3b)
after the fifth run portrayed the aggregation of the particles that
might have reduced the activity of nano-S, affording poorer
yield.
Table 2. Nano-S-Catalyzed Synthesis of Amidoalkyl
Naphthols
ab
,
entry
R1
R2
time (min)
yield (%)
The recycled catalyst could not be used directly because
some organic matter may get adsorbed on its surface.
Therefore, the regeneration of the activity of nano-S after the
fifth run was accomplished. To verify the decomposition of
catalyst after the fifth run (if any), EDX analysis was performed.
Interestingly, nano-S after the fifth run confirmed the existence
of sulfur only (Figure S4a, Supporting Information). With this
pleasing observation, the recycled catalyst was first washed with
hot deionized water to remove most organic adsorbates and
impurities. Calcination was then performed at 60 °C under
sonication (45 min) by putting in distilled THF to reactivate
the catalyst by collapsing the agglomeration.
The XRD pattern (Figure S4b, Supporting Information) of
reactivated nano-S after calcination under sonication revealed
the enhancement in the intensity and broadening of the peaks
(026), (117), (313), (044), (062), (066), and (357) and a
slight decrease in the intensity of (222) and (551) planes.
The TEM image (Figure S5, Supporting Information) of
reactivated nano-S explored the spherical particles with an
average diameter of 37 nm. The reusability test of reactivated
nano-S was performed from the model reaction (Scheme 2),
and the consequences are shown in Table S3 (Supporting
Information). Our data showed that the reactivated nano-S
could be reused up to the third consecutive run without
significant loss in its activity, and after that, its action slowed
down.
The “green-ness” of the present methodology was evaluated
by different parameters of green chemistry (Supporting
Information, Table S4) by considering Scheme 2 that
established the supremacy of nano-S over other catalysts. The
waste produced during the course of the reaction is the least in
our protocol compared to the other methodologies. Moreover,
the issues like solvent reusability and catalyst recyclability are
omitted by E-factor which absolutely raises the accuracy.
In conclusion, we have introduced a potent, benign, highly
active, and reusable nano-S for the one-pot synthesis of 1-
amidoalkyl naphthols under SFRC using our NOSE approach.
The method for the synthesis of nano-S is cheaper, and its
utilization in industry will leave almost zero waste production
along with easy isolation and regeneration of its activity. The
chemistry of nano-S as a catalyst is not explored yet in organic
1
2
C6H5
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
C6H5
C6H5
C6H5
C6H5
C6H5
30
15
15
35
45
30
30
30
30
60
60
10
25
30
25
45
30
30
30
25
40
98
94
94
92
92
92
94
95
91
84
85
90
91
95
90
90
95
95
95
95
90
4-ClC6H4
3
3-NO2C6H4
4-OCH3C6H4
4-OHC6H4
trans-C6H4CHCH
2-furyl
4
5
6
7
8
2-thienyl
9
2-CH3C6H4
CH3CH2
10
11
12
13
14
15
16
17
18
19
20
21
CH3CH2CH2
3-NO2C6H4
2-ClC6H4
C6H5
4-OHC6H4
trans-C6H4CHCH
C6H5
4-CH3C6H4
4-ClC6H4
4-OHC6H4
CH3CH2CH2
a
b
Yields refer to the isolated pure products. Products were
characterized by IR and NMR (1H and 13C spectroscopy, MS, and
also by comparing their melting points with the authentic ones.
hydroxyphenyl)-(2-hydroxynaphthalen-1-yl)methyl using a cat-
alytic amount of TBBDA.17 Since then and before there was no
report involving 4-hydroxybenzaldehyde as a starting material,
but using nano-S, it reacted efficiently with urea/acetamide/
benzamide and naphthol, furnishing the desired product in
excellent yields (entries 5, 15, and 20). No byproducts were
formed. Overall, the aldehydes in the liquid state favored the
product formation efficiently due to the best possible mixing,
although the reactions were conducted under SFRC.
A plausible mechanism explaining the sequence of the events
is tailored in Figure S2 (Supporting Information). We
presumed that the reaction proceeded via ortho-quinone
methides (o-QMs)19 (I) formed by the nucleophilic addition
of 2-naphthol to an aldehyde which was activated by nano-S.
Finally, (I) reacted with amides/urea via Michael addition to
produce amidoalkyl naphthols. The activation of the aldehydes
C
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The Journal of Organic Chemistry
Note
118.6, 56.1, 50.1; IR (KBr pellets) νmax (cm−1) 3481 (N−H), 3370
(O−H), 3265 (NH2), 2977 (C−H), 1637 (CO); m/z (GC-MS)
322.13 [M+]. Anal. Calcd for C19H18N2O3: C, 70.79; H, 5.63; N, 8.69.
Found: C, 70.73; H, 5.33; N, 8.61.
synthesis; therefore, we believe that this protocol is going to be
a breakthrough for its catalytic application.
EXPERIMENTAL SECTION
[(2-Hydroxynaphthalen-1-yl)-(4-hydroxyphenyl)methyl]urea16e
(Table 2, entry 5): White solid (283.36 mg, 92%); mp 146.7−148.6
■
Typical Procedure for the Synthesis of Nano-S. Elemental
sulfur (1 g) was taken in a silica crucible and heated in an oven preset
at 120 °C for 25 min. The melted substance was brought down to
room temperature and then placed over an ice bath. Finally, it was
grinded with mortar and pestle. This process was repeated thrice. After
that, it was washed with double distilled water (3 × 15 mL) and dried
in oven at 100 °C. The synthesis of nano-S at 180 °C was
accomplished akin to the above.
1
°C, Rf = 0.31 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
TMS) δ 10.51 (br, s, 1H, OH), 8.13−7.95 (m, 6H, Ar−H), 7.57 (br, s,
1H, NH), 7.20−6.98 (m, 4H, Ar−H), 6.69 (s, 1H, CH), 5.79 (s, 2H,
NH2); 13C NMR (100 MHz, DMSO-d6) δ 160.7, 150.5, 143.5, 132.5,
129.0, 129.6, 128.1, 127.8, 127.3, 125.6, 124.8, 122.6, 122.1, 119.8,
47.5; IR (KBr pellets) νmax (cm−1) 3458 (N−H), 3340 (O−H), 3287
(NH2), 2965 (C−H), 1656 (CO); m/z (GC-MS) 308.12 [M+].
Anal. Calcd for C18H16N2O3: C, 70.12; H, 5.23; N, 9.09. Found: C,
70.19; H, 4.93; N, 9.03.
Representative Procedure for Synthesis of Amidoalkyl
Naphthols (Table 2, entry 1). A 1:1:1 mixture of 2-naphthol
(0.144 g, 1 mmol), benzaldehyde (0.102 mL, 1 mmol), urea (0.060 g,
1 mmol), and nano-S (S8-NP) (0.00896 g, 3.5 mol %) was taken in a
mortar and grinded with a pestle. The grinded mixture was transferred
in a round-bottom flask (50 mL) and placed in a preheated oil bath at
50 °C under SFRC by stirring under aerobic condition for the required
time. The progress of the reaction was monitored by TLC. After
completion (confirmed by TLC), the reaction mixture was brought
down to room temperature and ethyl acetate (5 mL) was added to it.
It was then ultracentrifuged (3500 rpm) to pellet out the nano-S. The
separated catalyst was washed with hot ethanol (3 × 10 mL),
decanted, and finally dried in an oven at 100 °C. The reaction mixture
containing the desired product was purified either by column
chromatography or TLC preparative or in few cases by recrystalliza-
tion from hot ethanol. The analytical data of this product (0.28616 g,
98% yield) are in good accord with the reported data.19a This
procedure was followed for all of the products listed in Table 2.
Analytical Data for All Products. [(2-Hydroxynaphthalen-1-
yl)phenylmethyl]urea14a (Table 2, entry 1): White solid (286.16 mg,
98%); mp 171.2−173.5 °C, Rf = 0.37 (50% AcOEt/hexane); 1H NMR
(400 MHz, DMSO-d6, TMS) δ 9.99 (br, s, 1H, OH), 7.75−7.70 (m,
Ar−H), 7.35 (br, s, 1H, NH), 7.17−7.13 (m, Ar−H), 6.90 (s, 1H,
CH), 5.79 (s, 2H, NH2); 13C NMR (100 MHz, DMSO-d6, TMS) δ
159.1, 153.3, 144.7, 132.5, 131.1, 129.5, 129.1, 128.3, 126.4, 126.2,
122.9, 121.2,119.7, 48.6; IR (KBr pellets) νmax (cm−1) 3453 (N−H),
3382 (O−H), 3231 (NH2), 2956 (C−H), 1661 (CO); m/z (GC-
MS) 292.12 [M+]. Anal. Calcd (%) for C18H16N2O2: C, 73.95; H,
5.52; N, 9.58. Found: C, 74.04; H, 5.22; N, 9.64.
[1-(2-Hydroxynaphthalen-1-yl)-3-phenylallyl]urea (This Work)
(Table 2, entry 6): Pale yellow solid (292.56 mg, 92%); mp 169.7−
173.2 °C, Rf = 0.25 (50% AcOEt/hexane); 1H NMR (400 MHz,
DMSO-d6, TMS) δ 10.54 (br, s, 1H, OH), 8.11 (d, J = 7.5 Hz, 1H),
8.35 (d, J = 7.5 Hz, 1H), 7.75−7.71 (m, 6H, Ar−H), 7.55 (br, s, 1H,
NH), 6.91 (s, 1H, CH), 5.82 (s, 2H, NH2); 13C NMR (100 MHz,
DMSO-d6) δ 168.6, 153.3, 150.6, 144.8, 136.3, 132.3, 129.3, 128.6,
128.0, 127.5, 127.1, 126.6, 126.1, 123.5, 122.1, 118.9, 118.1, 49.8; IR
(KBr pellets) νmax (cm−1) 3418 (N−H), 3353 (O−H), 3278 (NH2),
2970 (C−H), 1653 (CO); m/z (GC-MS) 318.14 [M+]. Anal. Calcd
for C20H18N2O2: C, 75.45; H, 5.70; N, 8.80. Found: C, 75.30; H, 5.96;
N, 8.89.
[Furan-2-yl-(2-hydroxynaphthalen-1-yl)methyl]urea20 (Table 2,
entry 7): Off white solid (265.08 mg, 94%); mp 162.3−163.7 °C, Rf =
1
0.35 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6, TMS) δ
9.97 (s, 1H, OH), 7.75−7.69 (m, 6H, Ar−H), 7.39 (s, 1H, NH),
6.86−6.88 (m, 3H, Ar−H), 6.02 (s, 1H, CH), 5.76 (s, 2H, NH2); 13
C
NMR (100 MHz, DMSO-d6, TMS) δ 159.6, 156.8, 153.7, 141.8,
132.8, 129.7, 129.0, 128.7, 126.9, 122.9, 119.0, 118.2, 110.8, 105.6,
50.2; IR (KBr pellets) νmax (cm−1) 3471 (N−H), 3392 (O−H), 3254
(NH2), 2987 (C−H), 1669 (CO); m/z (GC-MS) 282.10 [M+].
Anal. Calcd (%) for C16H14N2O3: C, 68.07; H, 5.00; N, 9.92. Found:
C, 68.45; H, 4.93; N, 10.12.
[(2-Hydroxynaphthalen-1-yl)-thiophen-2-yl-methyl]urea16b
(Table 2, entry 8): Light yellow solid (283.10 mg, 95%); mp 159.2−
161.7 °C, Rf = 0.36 (50% AcOEt/hexane); 1H NMR (400 MHz,
DMSO-d6, TMS) δ 9.95 (s, 1H, OH), 7.77−7.71 (m, 6H, Ar−H), 7.33
(s, 1H, NH), 6.83−6.88 (m, 3H, Ar−H), 6.22 (s, 1H, CH), 5.80 (s,
2H, NH2); 13C NMR (100 MHz, DMSO-d6, TMS) δ 160.1, 157.3,
154.4, 141.9, 133.4, 129.8, 129.2, 128.8, 126.2, 122.7, 119.2, 118.5,
110.3, 105.9, 49.8; IR (KBr pellets) νmax (cm−1) 3474 (N−H), 3398
(O−H), 3258 (NH2), 2982 (C−H), 1672 (CO); m/z (GC-MS)
298.08 [M+]. Anal. Calcd (%) for C16H14N2O2S: C, 64.41; H, 4.73; N,
9.39. Found: C, 64.58; H, 4.99; N, 9.43.
[(4-Chlorophenyl)-(2-hydroxynaphthalen-1-yl)methyl]urea21
(Table 2, entry 2): White solid (306.44 mg, 94%); mp 210.6−212.7
1
°C, Rf = 0.35 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
TMS) δ 9.96 (br, s, 1H, OH), 7.79−7.71 (m, Ar−H, 6H), 7.36 (br, s,
1H, NH), 7.24−7.10 (m, Ar−H, 4H), 6.86 (s, 1H, CH), 5.80 (s, 2H,
NH2); 13C NMR (100 MHz, DMSO-d6, TMS) δ 159.0, 153.4, 144.0,
132.5, 130.8, 129.7, 129.1, 128.3, 128.1, 127.1, 123.0, 118.9, 49.9; IR
(KBr pellets) νmax (cm−1) 3485 (N−H), 3390 (O−H), 3192 (NH2),
2955 (C−H), 1650 (CO); m/z (GC-MS) 326.08 [M+]. Anal. Calcd
(%) for C18H15ClN2O2: C, 66.16; H, 4.63; N, 8.57. Found: C, 66.08;
H, 4.43; N, 8.67.
N-[(2-Hydroxynaphthalen-1-yl)-o-tolylmethyl]acetamide22
(Table 2, entry 9): Off white solid (277.55 mg, 91%); mp 200.3−202.7
1
°C, Rf = 0.38 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
[(2-Hydroxynaphthalen-1-yl)-(3-nitrophenyl)methyl]urea21
(Table 2, entry 3): Light yellow powder (316.78 mg, 94%); mp 186.6−
188.1 °C, Rf = 0.31 (50% AcOEt/hexane); 1H NMR (400 MHz,
DMSO-d6, TMS) δ 9.91 (br, s, 1H, OH), 8.11−8.07 (m, 6H, Ar−H),
7.91−7.85 (m, 4H, Ar−H), 7.34 (br, s, 1H, NH), 6.84 (s, 1H, CH),
5.82 (s, 2H, NH2); 13C NMR (100 MHz, DMSO-d6, TMS) δ 161.7,
153.4, 147.3, 145.0, 133.4, 132.1, 130.2, 129.2, 128.9, 128.6, 128.1,
127.3, 123.3, 119.1, 49.4; IR (KBr pellets) νmax (cm−1) 3484 (N−H),
3374 (O−H), 3260 (NH2), 2971 (C−H), 1632 (CO); m/z (GC-
MS) 337.11 [M+]. Anal. Calcd for C18H15N3O4: C, 64.09; H, 4.48; N,
12.46. Found: C, 64.14; H, 4.49; N, 12.66.
TMS) δ 9.98 (br, s, 1H, OH), 8.04−7.89 (m, 6H, Ar−H), 7.30−7.21
(m, 4H, Ar−H), 6.65 (br, s, 1H, NH), 5.77 (s, 1H, CH), 2.27 (s, 3H,
CH3), 1.89 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ 167.5,
152.7, 143.5, 139.5, 134.3, 132.4, 129.2, 128.6, 128.1, 126.3, 125.4,
123.4, 122.0, 118.3, 50.1, 22.7, 19.4; IR (KBr pellets) νmax (cm−1) 3422
(N−H), 3322 (O−H), 2993 (C−H), 1625 (CO); m/z (GC-MS)
305.14 [M+]. Anal. Calcd (%) for C20H19NO2: C, 78.66; H, 6.27; N,
4.59. Found: C, 78.60; H, 6.57; N, 4.64.
N-[1-(2-Hydroxynaphthalen-1-yl)-propyl]-acetamide23 (Table 2,
entry 10): White solid (204.12 mg, 84%); mp 172.9−174.4 °C, Rf =
1
0.42 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6, TMS) δ
[(2-Hydroxynaphthalen-1-yl)-(4-methoxyphenyl)methyl]urea10a
(Table 2, entry 4): White solid (296.24 mg, 92%); mp 182.3−184.7
10.05 (br, s, 1H, OH), 8.64 (br, s, 1H, NH), 7.82−7.75 (m, 6H, Ar−
H), 6.24 (t, 1H, J = 7.3 Hz, CH), 2.17 (s, 3H, CH3), 1.91−1.97 (m,
1H, CH2), 0.93 (t, 3H, J = 7.3 Hz, CH3); 13C NMR (100 MHz,
DMSO-d6) δ 166.4, 152.3, 134.6, 132.0, 131.3, 128.6, 128.1, 127.7,
127.2, 126.8, 126.1, 122.6, 119.4, 118.0, 48.6, 36.2, 19.8, 13.7; IR (KBr
pellets) νmax (cm−1) 3418 (N−H), 3228 (O−H), 3004 (C−H), 1636
(CO); m/z (GC-MS) 243.13 [M+]. Anal. Calcd (%) for
1
°C, Rf = 0.38 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
TMS) δ 10.03 (br, s, 1H, OH), 7.95−7.89 (m, 6H, Ar−H), 7.44 (br, s,
1H, NH), 7.28−7.23 (m, 4H, Ar−H), 6.88 (s, 1H, CH), 5.79 (s, 2H,
NH2), 3.57 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ 162.2,
153.4, 142.5, 135.5, 133.6, 129.5, 128.9, 128.2, 126.1, 123.5, 122.1,
D
dx.doi.org/10.1021/jo302682k | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
C15H17NO2: C, 74.05; H, 7.04; N, 5.76. Found: C, 74.12; H, 7.37; N,
5.56.
C21H19NO2: C, 79.47; H, 6.03; N, 4.41. Found: C, 79.51; H, 6.09; N,
4.77.
N-[1-(2-Hydroxynaphthalen-1-yl)butyl]acetamide23 (Table 2,
entry 11): White solid (218.45 mg, 85%); mp 221.3−223.8 °C, Rf =
N-[(2-Hydroxynaphthalen-1-yl)-phenylmethyl]benzamide14a
(Table 2, entry 17): White solid (335.35 mg, 95%); mp 235.1−237.5
1
1
0.40 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6, TMS) δ
°C, Rf = 0.25 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
10.15 (br, s, 1H, OH), 8.60 (br, s, 1H, NH), 7.80−7.73 (m, 6H, Ar−
H), 6.04 (t, 1H, J = 7.7 Hz, CH), 2.12 (s, 3H, CH3), 1.81−1.73 (m,
1H, CH2), 1.36−1.29 (m, 1H, CH2), 0.96 (t, 3H, J = 7.7 Hz, CH3);
13C NMR (100 MHz, DMSO-d6) δ 163.4, 152.1, 134.6, 132.4, 131.3,
129.1, 128.7, 128.2, 127.3, 126.7, 126.1, 122.0, 119.1, 118.3, 47.9, 36.6,
19.8, 13.7; IR (KBr pellets) νmax (cm−1) 3451 (N−H), 3234 (O−H),
3041 (C−H), 1636 (CO); m/z (GC-MS) 257.14 [M+]. Anal. Calcd
(%) for C16H19NO2: C, 74.68; H, 7.44; N, 5.44. Found: C, 74.93; H,
7.62; N, 5.74.
TMS) δ 10.34 (br, s, 1H, OH), 8.17−8.11 (m, 6H, Ar−H), 7.92−7.87
(m, 5H, Ar−H), 7.40 (br, s, 1H, NH), 7.20−7.14 (m, 5H, Ar−H),
6.07 (s, 1H, CH); 13C NMR (100 MHz, DMSO-d6) δ 169.5, 153.4,
148.2, 145.2, 134.8, 133.4, 132.8, 132.2, 130.8, 130.3, 129.7, 128.4,
128.1, 127.7, 127.1, 123.8, 122.6, 122.6, 121.0, 119.3, 118.1, 49.7; IR
(KBr pellets) νmax (cm−1) 3475 (N−H), 3361 (O−H), 2984 (C−H),
1656 (CO); m/z (GC-MS) 353.14 [M+]. Anal. Calcd for
C24H19NO2: C, 81.56; H, 5.42; N, 3.96. Found: C, 81.73; H, 5.51;
N, 3.90.
N-[(2-Hydroxynaphthalen-1-yl)-(3-nitrophenyl)methyl]-
acetamide14b (Table 2, entry 12): Pale yellow solid (302.40 mg,
90%); mp 240.2−241.6 °C, Rf = 0.36 (50% AcOEt/hexane); 1H NMR
(400 MHz, DMSO-d6, TMS) δ 10.03 (br, s, 1H, OH), 8.03−7.73 (m,
6H, Ar−H), 7.51 (br, s, 1H, NH), 7.11−7.02 (m, 4H, Ar−H), 6.10 (s,
1H, CH), 1.95 (s, 3H, CH3); 13C NMR (DMSO-d6, 100 MHz) δ
162.3, 154.2, 132.5, 130.1, 129.4, 128.8, 128.1, 127.3, 126.4, 123.3,
122.9, 122.1, 118.3, 117.0, 115.3, 114.1, 43.9, 22.3; IR (KBr pellets)
νmax (cm−1) 3436 (N−H), 3258 (O−H), 2997 (C−H), 1644 (CO);
m/z (GC-MS) 336.11 [M+]. Anal. Calcd (%) for C19H16N2O4: C,
67.85; H, 4.79; N, 8.33. Found: C, 67.49; H, 4.86; N, 8.40.
N-[(2-Chlorophenyl)-(2-hydroxynaphthalen-1-yl)methyl]-
acetamide24 (Table 2, entry 13): Off white solid (295.75 mg, 91%);
N-[(2-Hydroxynaphthalen-1-yl)-p-tolylmethyl]benzamide14b
(Table 2, entry 18): Light yellow solid (348.65 mg, 95%); mp 207.5−
209.8 °C, Rf = 0.27 (50% AcOEt/hexane); 1H NMR (400 MHz,
DMSO-d6, TMS) δ 9.91 (br, s, 1H, OH), 8.04−7.98 (m, 6H, Ar−H),
7.63 (br, s, 1H, NH), 7.23−7.14 (m, 9H, Ar−H), 6.07 (s, 1H, CH),
1.91 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6) δ 167.8, 153.1,
143.3, 139.5, 134.7, 132.9, 129.1, 128.8, 128.2, 126.3, 125.5, 123.4,
122.6, 119.4, 118.1, 48.7, 20.3; IR (KBr pellets) νmax (cm−1) 3419 (N−
H), 3317 (O−H), 3071 (C−H), 1623 (CO); m/z (GC-MS) 367.16
[M+]. Anal. Calcd for C25H21NO2: C, 81.72; H, 5.76; N, 3.81. Found:
C, 81.53; H, 6.11; N, 3.87.
N-[(4-Chlorophenyl)-(2-hydroxynaphthalen-1-yl)methyl]-
benzamide23 (Table 2, entry 19): Off white solid (367.65 mg, 95%);
1
1
mp 212.8−214.5 °C, Rf = 0.38 (50% AcOEt/hexane); H NMR (400
mp 179.0−181.6 °C, Rf = 0.24 (50% AcOEt/hexane); H NMR (400
MHz, DMSO-d6, TMS) δ 9.98 (br, s, 1H, OH), 7.94−7.88 (m, 6H,
Ar−H), 7.47 (br, s, 1H, NH), 7.29−7.36 (m, 4H, Ar−H), 6.03 (s, 1H,
CH), 1.91 (s, 3H, CH3); 13C NMR (100 MHz, DMSO-d6, TMS) δ
165.6, 154.1, 140.4, 133.5, 133.4, 132.8, 132.1, 130.3, 129.8, 129.1,
128.7, 127.6, 127.0, 123.1, 123.6, 119.2, 117.4, 48.6, 23.5; IR (KBr
pellets) νmax (cm−1) 3440 (N−H), 3251 (O−H), 2990 (C−H), 1645
(CO); m/z (GC-MS) 325.09 [M+]. Anal. Calcd (%) for
C19H16ClNO2: C, 70.05; H, 4.95; N, 4.30. Found: C, 69.96; H,
4.55; N, 4.45.
MHz, DMSO-d6, TMS) δ 10.06 (br, s, 1H, OH), 8.06−7.97 (m, 6H,
Ar−H), 7.43 (br, s, 1H, NH), 7.28−7.23 (m, 4H, Ar−H), 7.07−7.01
(m, 5H, Ar−H), 6.12 (s, 1H, CH); 13C NMR (100 MHz, DMSO-d6) δ
165.0, 153.3, 138.7, 134.1, 132.5, 132.1, 131.2, 130.6, 129.7, 128.4,
128.2, 128.0, 127.8, 127.3, 126.7, 126.2, 122.9, 122.4, 118.7, 116.6,
48.9; IR (KBr pellets) νmax (cm−1) 3440 (N−H), 3325 (O−H), 3070
(C−H), 1644 (CO); m/z (GC-MS) 387.10 [M+]. Anal. Calcd for
C24H18ClNO2: C, 74.32; H, 4.68; N, 3.61. Found: C, 74.26; H, 4.60;
N, 3.86.
N-[(2-Hydroxynaphthalen-1-yl)-phenylmethyl]acetamide14a
(Table 2, entry 14): White solid (276.45 mg, 95%); mp 228.3−229.5
N-[(2-Hydroxynaphthalen-1-yl)-(4-hydroxyphenyl)methyl]-
benzamide (This Work) (Table 2, entry 20): Light brown solid
(350.55 mg, 95%); mp 191.3−193.3 °C, Rf = 0.21 (50% AcOEt/
1
°C, Rf = 0.46 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6,
1
TMS) δ 9.70 (br, s, 1H, OH), 7.94−7.88 (m, 6H, Ar−H), 7.53 (br, s,
1H, CH), 7.21−7.07 (m, 5H, Ar−H), 2.01 (s, 3H, CH3); 13C (100
MHz, DMSO-d6, TMS) δ 167.6, 152.7, 144.7, 134.6, 128.9, 128.7,
128.1, 127.8, 127.1, 125.5, 124.7, 123.6, 122.3, 122.1, 118.2, 43.6, 21.7;
IR (KBr pellets) νmax (cm−1) 3459 (N−H), 3388 (O−H), 3007 (C−
H), 1660 (CO); m/z (GC-MS) 291.13 [M+]. Anal. Calcd (%) for
C19H17NO2: C, 78.33; H, 5.88; N, 4.81. Found: C, 78.70; H, 5.93; N,
4.91.
hexane); H NMR (400 MHz, DMSO-d6, TMS) δ 11.24 (br, s, 1H,
OH), 8.94 (br, s, 1H, NH), 8.11−8.05 (m, 6H, Ar−H), 7.81−7.76 (m,
4H, Ar−H), 7.21−7.15 (m, 5H, Ar−H), 6.79 (s, 1H, CH); 13C NMR
(100 MHz, DMSO-d6, TMS) δ 169.6, 156.4, 152.4, 149.2, 144.7,
139.2, 134.5, 132.5, 132.1, 130.0, 129.6, 129.2, 128.8, 128.1, 127.9,
127.1, 125.2, 124.4, 122.9, 122.2, 120.8, 119.3, 50.3 ; IR (KBr pellets)
νmax (cm−1) 3488 (N−H), 3366 (O−H), 2955 (C−H), 1655 (CO);
m/z (GC-MS) 369.14 [M+]. Anal. Calcd for C24H19NO3: C, 78.03; H,
5.18; N, 3.79. Found: C, 77.67; H, 5.22; N, 4.08.
N-[(2-Hydroxynaphthalen-1-yl)-(4-hydroxyphenyl)methyl]-
acetamide (This Work) (Table 2, entry 15): Light crimson solid
(276.30 mg, 90%); mp 185.8−189.6 °C, Rf = 0.29 (50% AcOEt/
N-[1-(2-Hydroxynaphthalen-1-yl)butyl]benzamide23 (Table 2,
entry 21): White solid (287.10 mg, 90%); mp 240.1−242.7 °C, Rf =
1
1
hexane); H NMR (400 MHz, DMSO-d6, TMS) δ 10.07 (br, s, 1H,
0.33 (50% AcOEt/hexane); H NMR (400 MHz, DMSO-d6, TMS) δ
OH), 7.71−7.68 (m, 6H, Ar−H), 7.44 (br, s, 1H, NH), 7.22−7.17 (m,
4H,, Ar−H), 6.41 (s, 1H, CH), 1.97 (s, 3H, CH3); 13C NMR (100
MHz, DMSO-d6, TMS) δ 167.2, 148.1, 140.3, 130.4, 129.7, 129.1,
128.4, 127.7, 127.2, 125.6, 124.1, 122.7, 122.1, 120.5, 119.0, 49.3 22.1;
IR (KBr pellets) νmax (cm−1) 3480 (N−H), 3365 (O−H), 2992 (C−
H), 1675 (CO); m/z (GC-MS) 307.12 [M+]. Anal. Calcd (%) for
C19H17NO3: C, 74.25; H, 5.58; N, 4.56. Found: C, 74.33; H, 5.52; N,
4.26.
10.08 (br, s, 1H, OH), 8.11−8.05 (m, 6H, Ar−H), 7.83−7.79 (m, 5H,
Ar−H), 7.31 (br, s, 1H, NH), 6.34 (t, 1H, J = 6.5 Hz, CH), 2.15 (s,
3H, CH3), 1.84−1.78 (m, 1H, CH2), 1.39−1.33 (m, 1H, CH2), 0.97
(t, 3H, J = 6.5 Hz, CH3); 13C NMR (100 MHz, DMSO-d6) δ 162.7,
155.3, 148.1, 144.6, 139.7, 139.2, 135.1, 133.7, 132.4, 129.3, 128.8,
128.3, 127.7, 126.2, 125.3, 122.8, 119.6, 118.4, 48.7, 36.3, 19.4, 13.3; IR
(KBr pellets) νmax (cm−1) 3469 (N−H), 3239 (O−H), 3010 (C−H),
1659 (CO); m/z (GC-MS) 319.16 [M+]. Anal. Calcd (%) for
C21H21NO2: C, 78.97; H, 6.63; N, 4.39. Found: C, 79.11; H, 6.92; N,
4.45.
N-[1-(2-Hydroxynaphthalen-1-yl)-3-phenylallyl]acetamide16c
(Table 2, entry 16): Off white solid (285.30 mg, 90%); mp 174.5−
176.0 °C, Rf = 0.28 (50% AcOEt/hexane); 1H NMR (400 MHz,
DMSO-d6, TMS) δ 11.03 (br, s, 1H, OH), 8.29 (d, J = 6.9 Hz, 1H),
8.17 (d, J = 6.9 Hz, 1H), 7.80−7.74 (m, 6H, Ar−H), 7.51 (br, s, 1H,
NH), 6.23 (s, 1H, CH), 2.05 (s, 3H, CH3); 13C NMR (100 MHz,
DMSO-d6) δ 169.1, 155.2, 151.4, 145.2, 134.4, 133.0, 130.2, 129.1,
128.7, 128.0, 127.5, 126.7, 126.2, 123.4, 122.3, 118.7, 118.2, 48.7, 21.3;
IR (KBr pellets) νmax (cm−1) 3411 (N−H), 3350 (O−H), 2989 (C−
H), 1659 (CO); m/z (GC-MS) 317.14 [M+]. Anal. Calcd for
ASSOCIATED CONTENT
■
S
* Supporting Information
Recycling potential of nano-S, turnover number (TON) for
nano-S, green metrics, Tables S1, S2, S3, and S4, list of figures,
and 1H and 13C NMR spectra of new compounds. This
E
dx.doi.org/10.1021/jo302682k | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Note
(17) Das, V. K.; Devi, R. R.; Raul, P. K.; Thakur, A. J. Green Chem.
2012, 14, 847.
(18) Nagal, G. Chem. Eng. 1997, 104, 125.
material is available free of charge via the Internet at http://
pubs.acs.org.
(19) (a) Das, B.; Laxminarayana, K.; Ravikanth, B.; Rao, B. R. J. Mol.
Catal. A: Chem. 2007, 261, 180. (b) Khodaei, M. M.; Khosropour, A.
R.; Moghanian, H. Synlett 2006, 6, 916.
(20) Cai, X.-H.; Guo, H.; Xie, B. Int. J. Chem. 2011, 3, 119.
(21) Khabazzadeh, H.; Saidi, K.; Seyedi, N. J. Chem. Sci. 2009, 121,
429.
AUTHOR INFORMATION
■
Corresponding Author
*Fax: (+)91(3712)267005/6. E-mail: ashim@tezu.ernet.in.
Notes
The authors declare no competing financial interest.
(22) Shaterian, H. R.; Yarahmadi, H.; Ghashang, M. Bioorg. Med.
Chem. Lett. 2008, 18, 788.
(23) Wang, M.; Liang, Y. Monatsh. Chem. 2011, 142, 153.
(24) Ali, D.; Hojatollah, K.; Kazem, S. ARKIVOC 2009, 7, 303.
ACKNOWLEDGMENTS
■
V.K.D. thanks UGC for Rajiv Gandhi National Fellowship.
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dx.doi.org/10.1021/jo302682k | J. Org. Chem. XXXX, XXX, XXX−XXX