Simple and efficient one-pot, three-component, solvent-free synthesis of β-enaminones via sonogashira coupling-michael addition sequences

Article abstract of DOI:10.1080/00397910801914343

A simple, efficient, and environmentally friendly one-pot, three-component synthesis of β-enaminones via Sonogashira coupling-Michael addition sequences under solvent-free conditions has been reported. Also the synthesis of β-enaminones has been achieved

Full text of DOI:10.1080/00397910801914343

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Simple and Efficient One‐Pot,
Three‐Component, Solvent‐Free Synthesis
of β‐Enaminones via Sonogashira
Coupling–Michael Addition Sequences
Sanjay S. Palimkar a , Vijaykumar S. More a & Kumar V. Srinivasan a
a Division of Organic Chemistry: Technology , National Chemical Laboratory ,
Pune, India
Published online: 25 Apr 2008.
To cite this article: Sanjay S. Palimkar , Vijaykumar S. More & Kumar V. Srinivasan (2008) Simple and Efficient
One‐Pot, Three‐Component, Solvent‐Free Synthesis of β‐Enaminones via Sonogashira Coupling–Michael
Addition Sequences, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 38:9, 1456-1469, DOI: 10.1080/00397910801914343
To link to this article: http://dx.doi.org/10.1080/00397910801914343
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Synthetic Communicationsw, 38: 1456–1469, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910801914343
Simple and Efficient One-Pot,
Three-Component, Solvent-Free Synthesis
of b-Enaminones via Sonogashira
Coupling–Michael Addition Sequences
Sanjay S. Palimkar, Vijaykumar S. More, and
Kumar V. Srinivasan
Division of Organic Chemistry: Technology, National Chemical
Laboratory, Pune, India
Abstract: A simple, efficient, and environmentally friendly one-pot, three-component
synthesis of b-enaminones via Sonogashira coupling–Michael addition sequences
under solvent-free conditions has been reported. Also the synthesis of b-enaminones
has been achieved in high yields by the direct reaction of amines with ynones under
solvent-free conditions.
Keywords: Alkynes, coupling, b-enaminones, Michael additions, solvent free, ynones
The chemical industry is one of the major contributors to environmental
pollution, because of the use of hazardous chemicals and in particular the
use of large amounts of highly flammable, volatile, and often toxic organic
solvents as reaction media as well as for processing, extraction, and purifi-
cation of the products. With increasing awareness of the concept of green
chemistry,[1] the chemical community has focused their attention on the devel-
opment of environmentally friendly processes based upon the replacement of
such volatile organic solvents with alternative nontoxic, nonflammable, and
nonvolatile media such as ionic liquids, supercritical fluids, and water, or
Received October 25, 2008
Address correspondence to Kumar V. Srinivasan, Division of Organic Chemistry:
Technology, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008,
India. E-mail: kv.srinivasan@ncl.res.in
1456

Synthesis of b-Enaminones
1457
alternatively the reactions have been carried out under solvent-free
conditions.[2]
Sequential transformations and multicomponent one-pot reactions are
always resource effective and environmentally acceptable and thus greener
than multistep reactions. They offer significant advantages over conventional
linear-step syntheses by reducing time and saving money, energy, and raw
materials, thus resulting in both economic and environmental benefits. At
the same time, diversity can be achieved for building up libraries by simply
varying each component.[3]
b-Enaminones are versatile synthetic intermediates, extensively
employed in organic synthesis.[4] In particular, such compounds are
important precursors for the sythesis of a wide variety of heterocycles.[5]
Also they have been employed as synthons of pharmaceutical compounds
because they have anti-epileptic,[6] antimolluscicidal, and larvicidal activi-
ties[7] and act as intermediates for the synthesis of naturally occurring
alkaloids.[8] The most well-known and explored route to b-enaminones
involves the direct condensation of b-dicarbonyl compounds with amines in
refluxing aromatic hydrocarbons with azeotropic removal of water.[9] In
recent years, several improved environmentally benign procedures have
been reported, including reaction of amines with b-dicarbonyl compounds
in the absence of catalyst in water and ionic liquid as reaction media,[10]
reactions catalyzed by Yb(OTf)3,[11] NaAuCl4,[12] Bi(TFA)3,[13] ceric
ammonium nitrate (CAN),[14] and erbium triflate.[15] Mu¨ller et al. have
reported a one-pot synthesis of b-enaminones via a Sonogashira coupling–
Michael addition reaction sequence that makes use of copper, a triphenyl
phosphine ligand, and volatile organic solvents such as tetrahydro furan
(THF) and methanol, all contributing to environmental pollution.[16]
Volatile organic solvents are high in the list of most damaging chemicals.
In their study, only reactive amines, primary and secondary aliphatic
amines, were used, and less reactive aromatic amines were not studied.
Moreover, many of these processes suffer from major or minor limitations
such as drastic reaction conditions, low yields, tedious workup procedures,
low selectivity, and co-occurrence of several side reactions.
Although several methods are available for the synthesis of b-enami-
nones, the development of a clean, facile, high-yielding and nonpolluting
protocols for the construction of this highly versatile synthetic intermediate
b-enaminone is still a synthetic challenge to organic chemists.
As part of our continuing interest in developing more efficient and envir-
onmentally benign methods in organic synthesis, our investigations include
for instance copper-, ligand-, and solvent-free synthesis of ynones,[17] novel
one-pot synthesis of 2,4-disubstituted-3H-benzo[b][1,4]diazepines in
water[3] and ionic liquid–promoted regiospecific synthesis of quinolines.[18]
Herein, we report a simple, atom-efficient, solvent-free, one-pot, three-
component synthesis of b-enaminones via coupling of acid chlorides with
terminal alkynes followed by the in situ Michael addition of the resulting

1458
S. S. Palimkar, V. S. More, and K. V. Srinivasan
Scheme 1.
ynones with amines in good to excellent isolated yields. Also we have reported
the synthesis of b-enaminones by the direct reaction of amines with corre-
sponding ynones in very high isolated yields also under solvent-free
conditions (Scheme 1).
Initially, the Sonogashira coupling of acid chlorides with 1-alkynes was
achieved under copper-, ligand-, and solvent-free conditions using
Pd(OAc)2 (0.2 mol%) as catalyst and 1 equivalent of triethyl amine as the
base[17] followed by the in situ addition of respective amines, and the
resulting reaction mixture was further subjected to heating at 80 8C for 20–
60 min to afford b-enaminones in very good to excellent isolated yields.
Also the direct reaction of amines with corresponding ynones have been
carried out at 80 8C for 20–60 min under neat conditions to afford the
b-enaminones in very high yields and purity, and there was no need of
column chromatography for the purification of the products in this case.
The results are summarized in Table 1. In all the cases, the reaction mixture
was a homogeneous melt at 80 8C under solvent-free conditions.
The scope and generality of the method could be validated by observing
that a wide range of amines including aromatic amines having both electron-
donating and electron-withdrawing groups and aliphatic primary and
secondary amines, were well tolerated, giving excellent isolated yields of
the b-enaminones. Moreover, the various acid chlorides and terminal
alkynes including different substituents such as methyl, methoxy, chloro,
and trifluoromethyl were equally facile for the reaction, resulting in the
formation of b-enaminones in excellent isolated yields.
The structure of all the b-enaminones synthesized were well characterized
by 1H, 13C, and nuclear overhauser effect spectroscopy (NOESY) NMR spectral
analyses, and their elemental analyses, were in conformity with their structures.
Most characteristically, in the 1H spectra the –NH proton signal appeared as a
broad singlet in the range d ¼ 11–13 (ppm) for primary amines, and olefinic
protons appear as a distinct singlet in the range d ¼ 5.50–6.02 (ppm). The con-
figuration of carbon–carbon double bond was determined by NOE experiment.

Table 1. Solvent-free synthesis of b-enaminones
Acid chloride
1
Reaction
time (min)
Yield
(%)a
Yield
(%)b
Entry
1
1-Alkyne 2
Amine 3
Product 4
60
85
99
2
3
1a
1a
2a
2a
60
60
80
79
99
98
4
1a
2a
50
82
99
(continued)

Table 1. Continued
Acid chloride
Reaction
time (min)
Yield
(%)a
Yield
(%)b
Entry
1
1-Alkyne 2
Amine 3
Product 4
5
1a
1a
1a
2a
60
60
30
76
95
99
98
99
99
6
7
2a
2a
8
1a
2a
20
90
99

9
1a
2a
2a
20
60
85
75
98
98
10
3a
11
12
1b
1b
2a
3d
3a
50
60
80
91
99
99
13
1b
3a
60
89
99
(continued)

Table 1. Continued
Acid chloride
Reaction
time (min)
Yield
(%)a
Yield
(%)b
Entry
1
1-Alkyne 2
Amine 3
Product 4
14
2a
3a
60
77
98
15
16
3g
3a
30
90
99
2b
60
96
98
aIsolated yields by using method A.
bIsolated yields by using method-B.

Synthesis of b-Enaminones
1463
The b-enaminones (4h and 4i) obtained from secondary amines have (E) con-
figuration and b-enaminones (4a–g, 4j–p) obtained from the primary amines
have the thermodynamically favored (Z) configuration, due to the hydrogen
bonding between oxygen atom of the carbonyl group and NH-hydrogen.
In conclusion, we disclose here a simple, clean, atom-efficient, and envir-
onmentally friendly one-pot, three-component reaction as well as a two-pot
procedure for the synthesis of b-enaminones via Sonogashira coupling–
Michael addition sequences. A simple experimental procedure, relatively
fast reaction rates, excellent yields, and selectivity and purity of product are
the key advantages of our protocol, enabling it to be operated in combi-
chem mode to generate libraries with a diverse array of the b-enaminones.
Various substituents (electron donating and electron withdrawing) deployed
on acid chlorides, terminal alkynes, and amines were well tolerated. Most sig-
nificantly, efficiency, cost-effectiveness, and green methodology will make
this procedure useful to academia as well as industry.
EXPERIMENTAL
All reactions requiring anhydrous conditions were performed under positive
pressure of argon using oven-dried glassware (110 8C), which was cooled
under argon. Triethyl amine was distilled from CaH2 and stored over
potassium hydroxide (KOH). Melting points were recorded in open capillaries
using a Buchi melting-point B-540 apparatus. Column chromatography was
performed using silica gel (60- to 120-mesh size), and thin-layer chromato-
graphy (TLC) was carried out using aluminum sheets precoated with silica
gel 60F254 (Merck). All chemicals used were reagent grade procured commer-
1
cially and used without further purification. H and 13C NMR spectra were
recorded on a Bruker Avance DPX 200 spectrometer by using TMS as
internal standard. Elemental analysis was performed on Flash EA 1112
Thermo Finnigan instrument.
General Procedure for Synthesis of b-Enaminones
Method A
Acid chloride (1 mmol), terminal alkyne (1 mmol), and dry triethyl amine
(1 mmol) were added dropwise to a stirred mixture of Pd(OAc)2
(0.2 mol%), at room temperature under an atmosphere of argon. The
reaction mixture was further stirred at room temperature for 10 min. After
completion of reaction as monitored by TLC, amine (1 mmol) was added to
the same flask. The resulting reaction mixture was further subjected to
heating at 80 8C in a preheated oil bath for the time indicated in Table 1.
After the completion of reaction, the reaction mixture was extracted with

1464
S. S. Palimkar, V. S. More, and K. V. Srinivasan
ethyl acetate and washed with water. The organic layer was separated and
dried over anhydrous MgSO4, followed by the evaporation of solvent to
obtain the crude product. The crude product was further purified by column
chromatography using ethyl acetate/petroleum ether as eluent to afford the
desired pure product.
Method B
Ynones were used synthesized by using our improved procedure, a protocol
which is free from the use of copper, ligand, and solvent.[17] A mixture of
ynones (1 mmol) and amines (1 mmol) was stirred at 80 8C in a preheated
oil bath for 20–60 min (Table 1). After the completion of reaction as
indicated by TLC, the reaction mixture was cooled and the product was re-
crystallized from the mixture of hexane–ethyl acetate (9:1) to afford analyti-
cally pure b-enaminones in excellent yields.
Characterization Data of b-Enaminones (4a–q)
(Z)-1-(4-Chlorophenyl)-3-phenyl-3-(phenylamino)prop-2-en-1-one (4a)
Yellow solid; mp 160–161 8C. 1H NMR (200 MHz, CDCl3) d ¼ 5.94 (s, 1H),
6.71 (d, J ¼ 7.42 Hz, 2H), 6.92 (dt, J ¼ 7.22, 1.23 Hz, 1H), 7.05 (dt, J ¼ 7.90,
1.63 Hz, 2H), 7.21–7.35 (m, 7H), 7.82 (dt, J ¼ 8.58, 1.88 Hz, 2H), 12.82 (br s,
1H). 13C NMR (50 MHz, CDCl3) d ¼ 96.5, 123.2, 124.3, 128.3, 128.5, 128.6,
128.7, 129.7, 135.6, 137.4, 138.2, 139.2, 161.9, 188.0. Anal. calcd. for
C21H16ClNO: C, 75.56; H, 4.83; N, 4.20. Found: C, 75.40; H, 4.60; N, 4.01.
(Z)-3-(4-Tolylamino)-1-(4-chlorophenyl)-3-phenylprop-2-en-1-one (4b)
Yellow solid; mp 158–159 8C. 1H NMR (200 MHz, CDCl3) d ¼ 2.24 (s, 3H),
5.99 (s, 1H), 6.69 (d, J ¼ 8.30 Hz, 2H), 6.93 (d, J ¼ 8.29 Hz, 2H), 7.32–7.43
(m, 7H), 7.90 (dt, J ¼ 8.60, 1.91 Hz, 2H), 12.90 (br s, 1H). 13C NMR
(50 MHz, CDCl3) d ¼ 20.7, 96.1, 123.2, 128.3, 128.5, 128.6, 129.3, 129.6,
134.1, 135.7, 136.5, 137.3, 138.3, 162.1, 187.8. Anal. calcd. for
C21H16ClNO: C, 75.97; H, 5.22; N, 4.03. Found: C, 75.93; H, 5.60; N, 3.80.
(Z)-3-(4-Isopropylphenylamino)-1-(4-chlorophenyl-3-phenylprop-2-
en-1-one (4c)
Yellow solid; mp 117–118 8C. 1H NMR (200 MHz, CDCl3) d ¼ 1.17
(d, J ¼ 6.82 Hz, 6H), 2.69–2.90 (m, 1H), 5.98 (s, 1H), 6.71
(d, J ¼ 8.44 Hz, 2H), 6.98 (d, J ¼ 8.44 Hz, 2H), 7.33–7.43 (m, 7H), 7.89
(dt, J ¼ 8.69, 1.99 Hz, 2H), 12.93 (br s, 1H). 13C NMR (50 MHz, CDCl3)
d ¼ 23.8, 33.4, 96.1, 123.0, 126.6, 128.3, 128.5, 128.6, 129.6, 135.7, 136.7,

Synthesis of b-Enaminones
1465
137.2, 138.3, 144.9, 162.0, 187.7. Anal. calcd. for C24H22ClNO: C, 76.69; H,
5.90; N, 3.73. Found: C, 76.50; H, 6.01; N, 3.81.
(Z)-3-(4-Methoxyphenylamino)-1-(4-chlorophenyl)-3-phenylprop-2-
en-1-one (4d)
Yellow solid; mp 126–127 8C. 1H NMR (200 MHz, CDCl3) d ¼ 3.72 (s, 3H),
5.98 (s, 1H), 6.64–6.78 (m, 4H), 7.32–7.42 (m, 7H), 7.89 (dt, J ¼ 8.60,
1.80 Hz, 2H), 12.91 (br s, 1H). 13C NMR (50 MHz, CDCl3) d ¼ 55.3, 95.6,
113.9, 124.9, 128.3, 128.5, 129.6, 132.2, 135.6, 137.2, 138.3, 156.6, 162.5,
187.6. Anal. calcd. for C22H18ClNO2: C, 72.62; H, 4.99; N, 3.85. Found: C,
72.40; H, 5.07; N, 4.01.
(Z)-3-(2-Bromo-4-methylphenylamino)-1-(4-chlorophenyl)-3-
phenylprop-2-en-1-one (4e)
Yellow viscous oil. 1H NMR (200 MHz, CDCl3) d ¼ 2.14 (s, 3H), 6.01
(s, 1H), 6.29 (d, J ¼ 8.23 Hz, 1H), 6.63 (d, J ¼ 9.61 Hz, 1H), 7.28–7.35
(m, 8H), 7.85 (dt, J ¼ 8.59, 1.94 Hz, 2H), 12.64 (br s, 1H). 13C NMR
(50 MHz, CDCl3) d ¼ 20.4, 97.2, 117.4, 125.6, 127.9, 128.2, 128.5, 128.6,
128.8, 129.8, 136.2, 135.5, 135.6, 135.7, 137.5, 138.0, 161.4, 188.3. Anal.
calcd. for C22H17BrClNO: C, 61.92; H, 4.02; N, 3.28. Found: C, 62.20; H,
4.35; N, 3.01.
(Z)-3-(4-Chlorophenylamino)-1-(4-chlorophenyl)-3-phenylprop-2-en-
1-one (4f)
Yellow solid; mp 187–188 8C. 1H NMR (200 MHz, CDCl3) d ¼ 5.96 (s, 1H),
6.62 (d, J ¼ 8.71 Hz, 2H), 7.00 (d, J ¼ 8.70 Hz, 2H), 7.26–7.36 (m, 7H), 7.81
(dt, J ¼ 8.71, 1.90 Hz, 2H), 12.77 (br s, 1H). 13C NMR (50 MHz, CDCl3)
d ¼ 96.9, 124.3, 128.2, 128.6, 128.7, 128.8, 128.9, 129.6, 129.9, 135.2,
137.6, 137.9, 161.5, 188.3. Anal. calcd. for C21H15Cl2NO: C, 68.49; H,
4.11; N, 3.80. Found: C, 68.20; H, 4.44; N, 3.66.
(Z)-3-(Benzylamino)-1-(4-chlorophenyl)-3-phenylprop-2-en-1-one (4g)
Pale yellow oil. 1H NMR (200 MHz, CDCl3) d ¼ 4.42 (d, J ¼ 6.57 Hz, 2H),
5.78 (s, 1H), 7.20–7.46 (m, 12H), 7.84 (d, J ¼ 8.60 Hz, 2H), 11.71 (br s, 1H).
13C NMR (50 MHz, CDCl3) d ¼ 48.4, 93.5, 126.8, 127.4, 127.6, 128.3, 128.4,
128.5, 128.7, 129.6, 135.1, 136.8, 138.1, 138.4, 167.0, 187.0. Anal. calcd. for
C22H18ClNO: C, 75.97; H, 5.22; N, 4.03. Found: C, 75.60; H, 5.48; N, 4.40.

1466
S. S. Palimkar, V. S. More, and K. V. Srinivasan
(E)-1-(4-Chlorophenyl)-3-phenyl-3-(piperidin-1-yl)prop-2-en-1-one (4h)
1
Pale yellow solid; mp 131–132 8C. H NMR (200 MHz, CDCl3) d ¼ 1.57
(m, 6H), 3.18 (m, 4H), 5.68 (s, 1H), 7.14–7.24 (m, 3H), 7.28–7.42
(m, 4H), 7.64–7.78 (m, 2H). 13C NMR (50 MHz, CDCl3) d ¼ 24.3, 25.7,
26.8, 49.2, 94.6, 128.0, 128.2, 128.3, 128.5, 128.7, 129.0, 129.2, 129.4,
136.4, 136.4, 136.7, 140.0, 164.9, 186.8. Anal. calcd. for C20H20ClNO: C,
73.72; H, 6.19; N, 4.30. Found: C, 73.78; H, 6.40; N, 4.21.
(E)-1-(4-Chlorophenyl)-3-(dibutylamino)-3-phenylprop-2-en-1-one (4i)
Pale yellow solid; mp 88–90 8C. 1H NMR (200 MHz, CDCl3) d ¼ 0.88
(m, 6H), 1.27 (m, 4H), 1.54 (m, 4H), 3.19 (m, 4H) 5.86 (s, 1H), 7.18–7.24
(m, 2H), 7.27–7.29 (m, 2H), 7.38–7.45 (m, 2H), 7.75 (d, J ¼ 8.63 Hz, 2H).
13C NMR (50 MHz, CDCl3) d ¼ 13.7, 20.1, 50.2, 92.9, 127.7, 127.9, 128.2,
128.4, 128.9, 136.3, 136.9, 140.4, 163.9, 185.4. Anal. calcd. for
C23H28ClNO: C, 74.68; H, 7.63; N, 3.79. Found: C, 74.43; H, 7.93; N, 3.82.
(Z)-1, 3-Diphenyl-3-(phenylamino)prop-2-en-1-one (4j)
Yellow solid; mp 101–102 8C. 1H NMR (200 MHz, CDCl3) d ¼ 6.09 (s, 1H),
6.79 (d, J ¼ 7.45 Hz, 2H), 6.99 (tt, J ¼ 7.18, 1.10 Hz, 1H), 7.13 (tt, J ¼ 7.83,
1.49 Hz, 2H) 7.30–7.50 (m, 8H), 7.95–7.99 (m, 2H), 12.90 (br s, 1H).
13C NMR (50 MHz, CDCl3) d ¼ 97.0, 123.2, 124.1, 127.2, 128.3, 128.5,
128.6, 128.7, 131.3, 135.8, 139.4, 139.8, 161.4, 189.6. Anal. calcd. for
C21H17NO: C, 84.25; H, 5.72; N, 4.68. Found: C, 84.18; H, 5.34; N, 4.71.
(Z)-3-(4-Methoxyphenylamino)-1,3-diphenylprop-2-en-1-one (4k)
Yellow solid; mp 126–127 8C. 1H NMR (200 MHz, CDCl3) d ¼ 3.71 (s, 3H),
6.04 (s, 1H), 6.67 (d, J ¼ 9.03 Hz, 2H), 6.75 (d, J ¼ 8.77 Hz, 2H), 7.29–7.39
(m, 5H), 7.41–7.47 (m, 3H), 7.95–7.97 (m, 2H), 12.91 (br s, 1H). 13C NMR
(50 MHz, CDCl3) d ¼ 55.2, 96.0, 113.9, 124.8, 127.1, 128.3, 128.4, 128.5,
131.1, 132.4, 135.7, 139.9, 156.4, 162.0, 189.2. Anal. calcd. for
C22H19NO2: C, 80.22; H, 5.81; N, 4.25. Found: C, 80.32; H, 5.63; N, 4.26.
(Z)-1-Phenyl-3-(phenylamino)-3-p-tolylprop-2-en-1-one (4l)
1
Yellow solid; mp 94–96 8C. H NMR (200 MHz, CDCl3) d ¼ 2.36 (s, 3H),
6.08 (s, 1H), 6.82 (d, J ¼ 7.43 Hz, 2H), 6.99 (tt, J ¼ 7.32, 1.26 Hz, 1H),
7.10–7.18 (m, 4H), 7.25–7.32 (m, 2H), 7.41–7.50 (m, 3H), 7.94–7.99
(m, 2H), 12.90 (br s, 1H). 13C NMR (50 MHz, CDCl3) d ¼ 21.3, 96.8,
123.2, 124.0, 127.2, 128.3, 128.6, 129.2, 131.2, 132.8, 139.5, 139.9, 161.6,
189.5. Anal. calcd. for C22H19NO: C, 84.31; H, 6.11; N, 4.47. Found: C,
84.30; H, 6.09; N, 4.26.

Synthesis of b-Enaminones
1467
(Z)-3-(4-Methoxyphenyl)-1-phenyl-3-(phenylamino)prop-2-en-1-one (4m)
1
Yellow solid; mp 96–98 8C. H NMR (200 MHz, CDCl3) d ¼ 3.81 (s, 3H),
6.07 (s, 1H), 6.80–6.87 (m, 4H), 6.99 (t, J ¼ 7.36 Hz, 1H), 7.15
(t, J ¼ 7.89, 2H), 7.31–7.49 (m, 5H), 7.94–7.99 (m, 2H), 12.89 (br s, 1H).
13C NMR (50 Hz, CDCl3) d ¼ 55.2, 96.6, 113.8, 123.2, 123.9, 127.1, 127.8,
128.3, 128.7, 129.9, 131.1, 139.6, 139.9, 160.7, 161.3, 189.3. Anal. calcd.
for C22H19NO2: C, 80.22; H, 5.81; N, 4.25. Found: C, 80.30; H, 5.78; N, 4.54.
(Z)-3-Phenyl-3-(phenylamino)-1-p-tolylprop-2-en-1-one (4n)
Yellow solid; mp 137–139 8C. 1H NMR (200 MHz, CDCl3) d ¼ 2.33 (s, 3H),
6.00 (s, 1H), 6.69 (d, J ¼ 7.58 Hz, 2H), 6.89 (t, J ¼ 7.11 HZ, 1H), 7.04
(t, J ¼ 7.82 Hz, 2H), 7.15–7.35(m, 7H), 7.79 (d, J ¼ 8.32 Hz, 2H), 12.80
(br s, 1H). 13C NMR (50 MHz, CDCl3) d ¼ 21.5, 96.9, 123.1, 123.9, 127.3,
128.3, 128.5, 128.6, 129.0, 129.6, 135.9, 137.1, 139.5, 141.7, 161.1, 189.5.
Anal. calcd. for C22H19NO: C, 84.31; H, 6.11; N, 4.47. Found: C, 84.53; H,
6.22; N, 4.52.
(Z)-3-(Benzylamino)-3-(4-(trifluoromethyl)phenyl)-1-o-tolylprop-2-
en-1-one (4o)
Pale yellow oil. 1H NMR (200 MHz, CDCl3) d ¼ 3.44 (s, 3H), 4.30
(d, J ¼ 6.57, 2H), 5.38 (s, 1H), 7.09–7.26 (m, 8H), 7.37–7.44 (m, 3H),
7.58 (d, J ¼ 8.08 Hz, 2H), 11.39 (br s, 1H). 13C NMR (50 MHz, CDCl3)
d ¼ 20.4, 48.3, 98.1, 120.9, 125.4, 125.5, 125.6, 126.7, 127.5, 128.2, 128.7,
129.3, 131.1, 131.8, 135.9, 138.1, 138.7, 141.4, 164.2, 194.1. Anal. calcd.
for C24H20F3NO: C, 72.90; H, 5.10; N, 3.54. Found: C, 73.01; H, 5.20; N,
3.72.
(Z)-3-(Phenylamino)-1-(thiophen-2-yl)-3-p-tolylprop-2-en-1-one (4p)
Yellow solid; mp 110–111 8C. 1H NMR (200 MHz, CDCl3) d ¼ 2.36 (s, 3H),
5.95 (s, 1H), 6.78 (d, J ¼ 7.66 Hz, 2H), 6.98 (tt, J ¼ 7.26, 2.15 Hz, 1H),
7.08–7.16 (m, 5H), 7.27 (d, J ¼ 8.32, 2H), 7.52 (dd, J ¼ 3.93, 1.15 Hz,
1H), 7.65 (dd, J ¼ 2.66, 1.01 Hz, 1H), 12.56 (br s, 1H). 13C NMR
(50 MHz, CDCl3) d ¼ 21.3, 96.6, 122.9, 123.9, 127.8, 128.2, 128.4, 128.6,
129.2, 130.9, 132.6, 139.5, 139.9, 146.8, 161.2, 182.3. Anal. calcd. for
C20H17NOS: C, 75.20 H, 5.36; N, 4.39. Found: C, 75.02; H, 5.13; N, 4.40.
ACKNOWLEDGMENT
S. S. P. thanks the CSIR, New Delhi, for the award of a research fellowship.

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S. S. Palimkar, V. S. More, and K. V. Srinivasan
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