The chemistry of α,β-ditosyloxyketones: new and convenient route for the synthesis of 1,4,5-trisubstituted pyrazoles from α,β-chalcone ditosylates

Article abstract of DOI:10.1016/j.tet.2009.10.001

The reaction of α,β-chalcone ditosylates with various reagents such as phenylhydrazine hydrochloride, semicarbazide hydrochloride and thiosemicarbazide in suitable conditions leads to 1,2-aryl shift, thereby providing a novel route for the synthesis of 1,4,5-trisubstituted pyrazoles.

Full text of DOI:10.1016/j.tet.2009.10.001

Tetrahedron 65 (2009) 10175–10181
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
The chemistry of
a,
b-ditosyloxyketones: new and convenient route for the
synthesis of 1,4,5-trisubstituted pyrazoles from
a
,b
-chalcone ditosylates
,
a
a
b
a
Om Prakash a , Deepak Sharma , Raj Kamal , Rajesh Kumar , Reshmi R. Nair
*
a Department of Chemistry, Kurukshetra University, Kurukshetra 136119, Haryana, India
b Post Graduate Department of Chemistry, M.L.N. College, Yamuna Nagar-135001, Haryana, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of a,b-chalcone ditosylates with various reagents such as phenylhydrazine hydrochloride,
Received 7 June 2009
Received in revised form
23 September 2009
Accepted 1 October 2009
Available online 6 October 2009
semicarbazide hydrochloride and thiosemicarbazide in suitable conditions leads to 1,2-aryl shift, thereby
providing a novel route for the synthesis of 1,4,5-trisubstituted pyrazoles.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
a
a
,
,
b
b
-Chalcone dibromides
-Chalcone ditosylates
1,4,5-Trisubstituted pyrazoles
Hydroxy(tosyloxy)iodobenzene
O
C
O
C
OTs OTs
CH CH Ar'
2
KOH, ROH
reflux
Ar
CH2Ar'
1. Introduction
Ar
Ar
ð1Þ
ð2Þ
3
a
-Tosyloxyketones have been found to behave analogous to
-haloketones in most of their chemical transformations. A great
deal of work from our research group and others has emphasized
the advantages of -tosyloxyketones over
-haloketones.1,2 On the
other hand while the chemistry of -chalcone dibromides 1 is
well explored,3 the reactivity mode of
-chalcone ditosylates 2
has been studied recently in our research group for the first time.
The aim of the study is to explore the potential of -chalcone
R = H, Me, Et
a
KOH (Cat. amount),
MeOH
O
C
OTs OTs
O
C
Ar'
a
a
CH CH Ar'
Ar
CH CH(OMe)2
a,b
stirring, r.t.
a,b
2
4
Prompted by foregoing observations coupled with our interest
in the synthesis of heterocyclic compounds, we now became in-
terested to investigate the reactivity of -chalcone ditosylates 2
a,b
ditosylates 2 in organic synthesis with particular emphasis on
comparison with their dibromo analogs.
a,b
with phenylhydrazine hydrochloride, semicarbazide hydrochloride
and thiosemicarbazide. The results obtained from this study have
offered a novel convenient route for the synthesis of 1,4,5-tri-
substituted pyrazoles.
In our preliminary study it has been reported that the reaction of
a,b-chalcone ditosylates 2 with 2 equiv of potassium hydroxide
leads to 1,2-aryl shift and carbon–carbon bond cleavage thereby
providing new route for the synthesis of desoxybenzoins 3 Eq (1).4
Using catalytic amount of potassium hydroxide at room tempera-
2. Results and discussion
ture, the reaction however affords
thylacetals 4 Eq. (2).4 These results have shown that the reactivity
pattern of -chalcone ditosylates 2 is quite different from
a-aryl-b-ketoaldehyde dime-
Thus, various derivatives of
a,b-chalcone ditosylates 2aa–2dh
a
,b
a,b-
were prepared by the treatment of respective chalcone with
chalcone dibromides 1, which are known to undergo elimination
under the similar reaction conditions.3b
O
C
O
C
OTs OTs
CH CH Ar'
2
HTIB
CH Cl
Ar
CH CH Ar'
Ar
2
2
5
* Corresponding author. Tel.: þ91 1744 234366; fax: þ91 1744 238277.
E-mail address: dromprakash50@rediffmail.com (O. Prakash).
Scheme 1.
a,b-Ditosyloxylation of chalcones using HTIB.
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.10.001

10176
O. Prakash et al. / Tetrahedron 65 (2009) 10175–10181
Table 1
Physical data of
a
,b
-chalcone ditosylates 2
Entry
2
Ar
Ar0
Mpt.
Yielda (%)
1
2
3
4
5
6
7
8
aa
ab
ac
ae
af
ag
bb
bf
bg
bh
ca
cc
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
4-MeC6H4
4-MeC6H4
4-MeC6H4
4-MeC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-ClC6H4
C6H5
4-MeC6H4
4-MeOC6H4
4-BrC6H4
2-thienyl
3-methyl-2-thienyl
4-MeC6H4
2-thienyl
3-methyl-2-thienyl
5-methyl-2-thienyl
C6H5
4-MeOC6H4
2-thienyl
3-methyl-2-thienyl
C6H5
2-thienyl
3-methyl-2-thienyl
5-methyl-2-thienyl
134–136(136–138)6
114–115
138–140
110–112
120–122
146–147
128–129
138–139
118–120
135–136
132–133
93–94
154–155
110–112
108–110
128–130
148–150
144–145
65
61
71
62
62
61
68
67
67
68
62
69
65
64
60
57
58
62
9
10
11
12
13
14
15
16
17
18
cf
cg
da
df
dg
dh
4-ClC6H4
4-ClC6H4
4-ClC6H4
a
Yield (%) of the products was calculated with respect to the corresponding chalcones.
hydroxy(tosyloxy)iodobenzene (HTIB)5 according to the method of
Koser6 (Scheme 1)4(Table 1).
a similar manner and affords corresponding pyrazole (6ab–6dh) in
good yield (52–68%) (Scheme 2, Table 2).
We first examined the reaction of
phenylhydrazine hydrochloride with a view to compare their
reactivity with -chalcone dito-
-chalcone dibromides 1.7 Thus
sylate 2aa (0.001 mol) was refluxed with phenylhydrazine hydro-
chloride(0.002 mol)indimethylformamide (25 mL)for 3 h. Theusual
work up of the reaction afforded single colorless product in 76% yield.
The melting point and spectral data (IR, NMR) of the product matched
withthestructure of 1,4,5-triphenylpyrazole (6aa). To study the scope
a
,
b
-chalcone ditosylates 2 with
In the light of encouraging results obtained from the studies on
the reactivity of a,b-chalcone ditosylates 2 with phenylhydrazine
a,b
a,b
hydrochloride, it was thought of significant interest to examine the
reactivity of 2 with other nucleophilic carbonyl reagents namely,
semicarbazide hydrochloride and thiosemicarbazide. Based on our
previous observations, it was anticipated that the reaction of 2 with
semicarbazide hydrochloride and thiosemicarbazide might afford
4,5-disubstituted pyrazole-1-carboxamides and 4,5-disubstituted
pyrazole-1-thiocarboxamides, respectively.
of reaction a wide range of substituted a,b-chalcone ditosylates (2ab–
2dh) were treated with phenylhydrazine hydrochlorideunder similar
The reaction of a,b-chalcone ditosylate 2aa was carried out sep-
conditions. It was observed that each of the derivatives behaves in
arately with semicarbazide hydrochloride and thiosemicarbazide
under the conditions described in Elba’s work10 on the reaction of
a,b-dibromochalcones. The reactions occurred according to our
Ar'
expectation and 4,5-diphenylpyrazole-1-carboxamide (7aa) and
4,5-diphenylpyrazole-1-thiocarboxamide (8aa) were obtained in
good yields. Using the similar conditions, the other derivatives of
a,b-chalcone ditosylate (2ab,2ac,2ae,2da) also gave the corre-
sponding 4,5-diarylpyrazole-1-carboxamides (7ab,7ac,7ae,7da).
O
C
OTs OTs
N
PhNHNH HCl
2.
Ar
Ar
CH CH Ar'
N
DMF,
Ph
Similarly other 4,5-diarylpyrazole-1-thiocarboxamide derivatives
2
6
(8ab,8ac,8da) were prepared in good yield from corresponding
chalcone ditosylates (2ab,2ac,2da) (Scheme 3, Tables 3 and 4). The
results clearly indicated that -chalcone ditosylates 2 behave in
a,b-
Scheme 2. Synthesis of 1,4,5-triarylpyrazoles from a,b-chalcone ditosylates.
a,b
a similar manner with different derivatives of carbonyl reagents and
provide a general approach for the synthesis of 1,4,5-trisubstituted
pyrazoles (6–8).
Table 2
Physical data of 1,4,5-triarylpyrazoles 6
Entry
6
Mpt.
Yielda (%)
1
2
3
4
5
6
7
8
aa
ab
ac
ae
af
ag
bb
bf
bg
bh
ca
cc
209–210(210–211)8
167–168(168–169)9
151(150–151)8
189–190
210–212
120–122
76
68
65
64
68
54
63
62
65
63
62
64
64
62
64
58
57
52
Ar'
NH CONHNH HCl
2
2.
N
EtOH,
Ar
N
CONH2
7
186–187
175–176
110–112
163–164
O
C
OTs OTs
9
Ar
CH CH Ar'
10
11
12
13
14
15
16
17
18
181–182(182–183)8
172–173(173)8
138–140
Ar'
2
cf
NH CSNHNH
2
2
N
N
cg
da
df
dg
dh
88–90
Ar
EtOH,
202(201–202)9
140–142
CSNH2
150–152
144–145
8
a
Yield (%) of the products was calculated with respect to the corresponding
-chalcone ditosylates.
Scheme 3. Synthesis of 4,5-diarylpyrazole-1-carboxamides and 4,5-diarylpyrazole-1-
thiocarboxamides from -chalcone ditosylates.
a
,
b
a,b

O. Prakash et al. / Tetrahedron 65 (2009) 10175–10181
10177
Table 3
with phenylhydrazine hydrochloride, semicarbazide hydrochloride
and thiosemicarbazide are known to give pyrazolines7,10 or 4-bro-
mrpyrazolines.10,12 The reactions have been proposed to occur
Physical data of 4,5-diarylpyrazole-1-carboxamides 7
Entry
7
Mpt.
Yielda (%)
through in situ formation of chalcones or
termediates depending upon the reaction conditions (Scheme 5).
a-bromochalcones as in-
1
2
3
4
5
aa
ab
ac
ae
da
155–156
110–112
97–98
140–142
139–140
62
63
65
53
58
O
C
Br Br
O
C
HCl.H2NNHX
Ar
CH CH Ar'
a
Ar
CH CH Ar'
Yield (%) of the products was calculated with respect to the corresponding
-chalcone ditosylates.
a
,
b
1
XNHNH2
Table 4
Ar
Physical data of 4,5-diarylpyrazole-1-thiocarboxamides 8
O
Entry
8
Mpt.
Yielda (%)
Ar
C
CBr CH Ar'
1
2
3
4
aa
ab
ac
da
160–162
88–90
110–112
148–149
61
63
65
59
N
N
Ar'
X
Br
Ar
a
Yield (%) of the products was calculated with respect to the corresponding
-chalcone ditosylates.
X = Ph; DMF
a
,
b
X = CSNH2; EtOH
N
N
Ar'
Although the mechanism of conversion 2/6–8 is not certain,
the exclusive formation of 1,4,5-trisubstituted pyrazoles 6–8 clearly
reveals that the conversion involves 1,2-aryl migrations. The
mechanism of this migration is very closely related to a pinacol
rearrangement and is outlined in Scheme 4. The first step of the
reaction is probably the nucleophilic substitution of –OTs group,
situated at position 3, by –NH2 group of reagent. The substitution is
followed by 1,2-aryl migration, resulting in the formation of in-
termediate 9, which subsequently undergoes cyclization in usual
manner to afford rearranged product. Of the various reported ex-
amples of rearrangement of this sort, two important ones are: (i)
bistosyloxylation of 1,1-diphenylethylene leading to desoxy-
benzoin6 (ii) copper-catalysed rearrangement of hydroxyketones.11
X
X = CONH2; EtOH
X = Ph; EtOH-C6H6 (2:1)
Scheme 5.
It is also worthwhile to mention that synthetic and structural
studies on 1,4,5-trisubstituted pyrazoles in literature are limited. One
of the literature reports involves three-step synthesis of 1,4,5-triaryl-
pyrazoles, starting from respective chalcones. Chalcones are first
converted to epoxides using H2O2/ꢀOH, then treated with BF3–Et2O
to get rearrangement and finally reaction with hydrazine affords
desired pyrazoles (Scheme 6).9 Considering the difficulty to access
3-oxo-2,3-diarylpropanals of the type A, this study provides an
alternative and convenient route to 1,4,5-trisubstituted pyrazoles.
XHN
O
C
OTs OTs
O
C
NH
CH CH Ar'
OTs
O
XNHNH
-TsOH
H
COAr
H
2
Ar
CH CH Ar'
Ar
-
/
H O OH
2 2
Ar
Ar'
Ar'
2
O
1,2-shift
-TsOH
BF -Et2O
C H
6 6
3
X
XHN
N
Ar'
H
N
N
O
PhNHNH
Ar'
Ar
2
O
N
Ar
C
CH CH
Ar
Ar
N
BF2
HO
Ar'
O
H
Ar'
Ph
9
A
-H O
2
Scheme 6.
X
N
3. Conclusion
N
X = Ph in 6
X = CONH in 7
It is evident from the study that unlike
-tosyloxyketones, which are analogous to each other in their chem-
ical reactions the reactivity pattern of -chalcone ditosylates 2 is
quite different from -chalcone dibromides 1. The actual reason for
this remarkable difference in the reactivity pattern is not known yet.
Detailinvestigations dealing with comparative studyare still goingon.
Finally, the noteworthy features of the report on the comparison of
a-haloketones and
2
Ar
a
X = CSNH in 8
2
a,b
Ar'
6,7 or 8
a,b
Scheme 4. Plausible mechanistic pathway for the formation of 1,4,5-trisubstituted
pyrazoles 6–8.
reactivity of a,b-chalcone ditosylates 2 and dibromo analogs 1 are:
It is interesting to note that bis-brominated homologs of these
substrates were never reported to undergo such rearrange-
1. It offers novel route for the synthesis of various 1,4,5-tri-
substituted pyrazoles.
ment.7,10,12,13 Instead, the reactions of
a,b-chalcone dibromides 1

10178
O. Prakash et al. / Tetrahedron 65 (2009) 10175–10181
2. All the a,b-chalcone ditosylates behave in similar manner on
J¼8.1 Hz); 6.96 (d, 1H, CH, J¼8.1 Hz); 7.04–7.05 (m, 2H, ArH); 7.18–7.24
(m, 4H, ArH); 7.30–7.38 (m, 3H, ArH); 7.41–7.44 (m, 2H, ArH); 7.49–7.50
(m, 2H, ArH); 7.71–7.73 (m, 2H, ArH); 7.79–8.21 (m, 2H, ArH). Elemental
analysis:Calculated for C29H25O7S2Br; C 55.3, H 3.9; Found C 54.8, H 3.8.
their reaction with phenylhydrazine hydrochloride, semi-
carbazide hydrochloride and thiosemicarbazide.
3. The newly developed route involves simple experimentation
with good yields.
4. There is possibility of using
to effect selective transformations, which are otherwise not
a,b-chalcone ditosylate derivatives
4.2.5. 1-Phenyl-3-(2-thienyl)-2,3-ditosyloxypropanone (2af). IR (nmax
,
in KBr): 1678 cmꢀ1 (CO stretch) 1H NMR (CDCl3, 300 MHz,
d): 2.42 (s,
possible through a,b-chalcone dibromides.
3H, CH3); 2.44 (s, 3H, CH3); 5.32 (d,1H, CH, J¼8.1 Hz); 6.93 (d,1H, CH,
J¼8.1 Hz); 6.84 (dd,1H, CH, J¼3.6 Hz); 6.86 (d, 1H, CH, J¼3.6 Hz); 7.15
(d,1H, CH, J¼3.6 Hz); 7.17–7.24 (m, 4H, ArH); 7.34–7.40 (m, 2H, ArH);
7.46–7.60 (m, 4H, ArH); 7.67–7.77 (m, 3H, ArH). Elemental analysis:
Calculated for C27H24O7S3; C 58.27, H 4.32; Found C 59.31, H 5.27.
4. Experimental
4.1. General
4.2.6. 3-(3-Methyl-2-thienyl)-1-phenyl-2,3-ditosyloxypropanone
Melting points were taken in open capillaries and are un-
corrected. IR spectra were recorded on Perkin–Elmer IR1800 spec-
trophotometer. The 1H NMR spectra were recorded on Bruker
300 MHz instrument. The chemical shifts are expressed in ppm units
downfield from an internal TMS standard. Elemental analyses were
carried out in Perkin–Elmer 2400 instrument. All commercially
available reagents were used as-received. Chalcones 5 were synthe-
sized according to literature procedures.14–19
(2ag). IR (nmax, in KBr): 1678 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
300 MHz, d): 2.19 (s, 3H, CH3); 2.43(s, 3H, CH3); 2.45(s, 3H, CH3); 5.34 (d,
1H, CH, J¼8.1 Hz); 6.63 (d, 1H, CH, J¼5.1 Hz); 6.92 (d, 1H, CH, J¼8.1 Hz);
7.10 (d, 1H, CH, J¼5.1 Hz); 7.12–7.13 (m, 3H, ArH); 7.24–7.27 (m, 4H, ArH);
7.53–7.64 (d, 4H, ArH); 7.75–7.76 (m, 2H, ArH. Elemental analysis: Cal-
culated for C28H26O7S3; C 58.95, H 4.56; Found C 59.37, H 4.64).
4.2.7. 1,3-Di(4-methylphenyl)-2,3-ditosyloxypropanone (2bb). IR
(
nmax, in KBr): 1681 cmꢀ1 (CO stretch) 1H NMR (CDCl3, 300 MHz,
d):
4.2. Preparation of
a
,
b
-chalcone ditosylates 2
2.18 (s, 3H, CH3); 2.20 (s, 3H, CH3); 2.34 (s, 6H, CH3); 5.03 (d, 1H, CH,
J¼8.1 Hz); 6.84–6.92 (m, 3H, ArH); 6.95 (d, 1H, CH, J¼8.1 Hz); 7.00–
7.12 (m, 4H, ArH); 7.26–7.30 (m, 3H, ArH); 7.39–7.42 (m, 3H, ArH);
7.60–7.72 (m, 3H, ArH). Elemental analysis: Calculated for
C31H30O7S2; C 64.3, H 5.2; Found C 63.7, H 4.7.
General procedure: To a solution of chalcone (5aa, 1.04 g,
0.005 mol) in dichloromethane (40 mL) was added [hydroxy
(tosyloxy)iodo]benzene (HTIB) (3.92 g, 0.01 mol). The resulting
mixturewas allowed to stir at 40–42 ꢁC. HTIB was highly insoluble in
dichloromethane, but gradually disappeared as the reaction pro-
ceeded. The stirring was allowed tocontinue for about 16–18 h. Then
the solvent was evaporated in vacuo. The gummy mass so obtained
was triturated with pet ether (Bp. 60–80 ꢁC) toremove iodobenzene.
The colorless solid obtained was thoroughly washed with water to
remove p-toluenesulphonic acid formed as byproduct. The solid
then recrystallized with acetonitrile to give the pure chalcone
ditosylate 2aa (yield 65%,1.78 g). Other derivatives were prepared in
a similar manner. Compounds 2aa–ae, ca, da were previously
reported, while 2af–ag, bb–bh, cc–cg, df–dh are new compounds.
4.2.8. 1-(4-Methylphenyl)-3-(2-thienyl)-2,3-ditosyloxypropanone
(2bf). IR (nmax, in KBr): 1681 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
300 MHz, d): 2.42 (s, 3H, CH3); 2.43 (s, 3H, CH3); 2.46 (s, 3H, CH3); 5.30
(d, 1H, CH, J¼8.1 Hz); 6.84 (dd, 1H, CH, J¼3.6 Hz); 6.86 (d, 1H, CH,
J¼3.6 Hz); 7.01 (d, 1H, CH, J¼8.1 Hz); 7.15 (d, 1H, CH, J¼3.6 Hz); 7.17–
7.27 (m, 4H, ArH); 7.46–7.60 (m, 4H, ArH); 7.67–7.77 (m, 4H, ArH). El-
emental analysis: Calculated for C28H26O7S3; C 58.95, H 4.56; Found C
59.27, H 4.67.
4.2.9. 1-(4-Methylphenyl)-3-(3-methyl-2-thienyl)-2,3-ditosyloxy-
1
propanone (2bg). IR (nmax, in KBr): 1681 cmꢀ1 (CO stretch) H NMR
4.2.1. 1,3-Diphenyl-2,3-ditosyloxypropanone (2aa)4. IR (nmax, in KBr):
(CDCl3, 300 MHz, d): 2.19 (s, 3H, CH3); 2.42 (s, 3H, CH3); 2.44 (s, 3H,
1681 cmꢀ1 (CO stretch) 1H NMR (CDCl3, 300 MHz,
d): 2.43 (s, 3H,
CH3); 2.46 (s, 3H, CH3); 5.36 (d, 1H, CH, J¼8.1 Hz); 6.64 (d, 1H, CH,
J¼5.1 Hz); 7.01 (d, 1H, CH, J¼8.1 Hz); 7.10 (d, 1H, CH, J¼5.1 Hz); 7.23–
7.30 (m, 4H, ArH); 7.48–7.56 (m, 4H, ArH); 7.62–7.71 (m, 4H, ArH). El-
emental analysis: Calculated for C29H28O7S3; C 59.58, H 4.79; Found C
60.33, H 4.85.
CH3); 2.46 (s, 3H, CH3); 5.03 (d, 1H, CH, J¼8.1 Hz); 6.96 (d, 1H, CH,
J¼8.1 Hz); 7.04–7.05 (m, 2H, ArH); 7.18–7.24 (m, 4H, ArH); 7.30–7.38
(m, 3H, ArH); 7.41–7.44 (m, 2H, ArH); 7.49–7.50 (m, 3H, ArH); 7.71–
7.73 (m, 2H, ArH); 7.79–8.21 (m, 2H, ArH).
4.2.2. 3-(4-Methylphenyl)-1-phenyl-2,3-ditosyloxypropanone
4.2.10. 1-(4-Methylphenyl)-3-(5-methyl-2-thienyl)-2,3-ditosyloxy-
(2ab)4. IR (nmax, in KBr): 1682 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
propanone (2bh). IR (nmax, in KBr): 1681 cmꢀ1 (CO stretch) 1H NMR
300 MHz,
d): 2.18 (s, 3H, CH3); 2.34 (s, 6H, CH3); 5.03 (d, 1H, CH,
(CDCl3, 300 MHz, d): 2.32 (s, 3H, CH3); 2.34 (s, 3H, CH3); 2.40 (s, 3H,
J¼8.1 Hz); 6.84–6.92 (m, 3H, ArH); 6.95 (d,1H, CH, J¼8.1 Hz); 7.0–7.12
(m, 4H, ArH); 7.26–7.30 (m, 3H, ArH); 7.39–7.42 (m, 3H, ArH); 7.60–
7.72 (m, 4H, ArH). Elemental analysis: Calculated for C30H28O7S2; C
63.8, H 4.9; Found C 62.6, H 4.2.
CH3); 2.42 (s, 3H, CH3); 5.12 (d, 1H, CH, J¼8.1 Hz); 6.41 (d, 1H, CH,
J¼3.3 Hz); 6.65 (d, 1H, CH, J¼3.3 Hz); 6.87 (d, 1H, CH, J¼8.1 Hz); 7.13–
7.21 (m, 4H, ArH); 7.55–7.61 (m, 4H, ArH); 7.62–7.71 (m, 4H, ArH). El-
emental analysis: Calculated for C29H28O7S3; C 59.58, H 4.79; Found C
60.33, H 5.39.
4.2.3. 3-(4-Methoxyphenyl)-1-phenyl-2,3-ditosyloxypropanone
(2ac)4. IR (nmax, in KBr): 1683 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
4.2.11. 1-(4-Methoxyphenyl)-3-phenyl-2,3-ditosyloxypropanone
300 MHz,
d): 2.42 (s, 3H, CH3); 2.43 (s, 3H, CH3); 3.75 (s, 3H, OCH3);
(2ca)4. IR (nmax, in KBr): 1674 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
5.00 (d, 1H, CH, J¼8.1 Hz); 6.65–6.68 (m, 2H, ArH); 6.98 (d, 1H, CH,
J¼8.1 Hz); 7.09–7.16 (m, 4H, ArH); 7.30–7.36 (m, 4H, ArH); 7.43–7.47
(m, 3H, ArH); 7.71–7.80 (m, 4H, ArH). Elemental analysis: Calcu-
lated for C30H28O8S2; C 62.0, H 4.8; Found C 61.8, H 4.3.
300 MHz, d): 2.41 (s, 3H, CH3); 2.42 (s, 3H, CH3); 3.81 (s, 3H, OCH3);
5.00 (d, 1H, CH, J¼8.1 Hz); 6.79–6.81 (m, 2H, ArH); 7.00 (d, 1H, CH,
J¼8.1 Hz); 7.14–7.22 (m, 8H, ArH); 7.43–7.45 (m, 3H, ArH); 7.70–7.74
(m, 4H, ArH). Elemental analysis: Calculated for C30H28O8S2; C 62.0,
H 4.8; Found C 61.5, H 4.2.
4.2.4. 3-(4-Bromophenyl)-1-phenyl-2,3-ditosyloxypropanone
(2ae)4. IR (nmax, in KBr): 1681 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
4.2.12. 1,3-Di(4-methoxyphenyl)-2,3-ditosyloxypropanone (2cc). IR
300 MHz,
d): 2.43 (s, 3H, CH3); 2.46 (s, 3H, CH3); 5.03 (d, 1H, CH,
( d):
nmax, in KBr): 1674 cmꢀ1 (CO stretch) 1H NMR (CDCl3, 300 MHz,

O. Prakash et al. / Tetrahedron 65 (2009) 10175–10181
10179
2.41 (s, 3H, CH3); 2.43 (s, 3H, CH3); 3.75 (s, 3H, OCH3); 3.81 (s, 3H,
OCH3); 4.95 (d, 1H, CH, J¼8.1 Hz); 6.64–6.67 (m, 2H, ArH); 6.67–
6.81 (m, 2H, ArH); 6.97 (d, 1H, CH, J¼8.1 Hz); 7.09–7.15 (m, 4H,
ArH); 7.43–7.46 (m, 3H, ArH); 7.69–7.8 (m, 3H, ArH); 7.95–7.98 (m,
2H, ArH). Elemental analysis: Calculated for C31H30O9S2; C 60.9, H
4.9; Found C 60.5, H 4.8.
mixture was extracted with dichloromethane in three portions
(3ꢂ50 mL). The organic extract was dried over anhydrous sodium
sulfate and filtered. Evaporation of dichloromethane in vacuo gave
the crude product, which was purified by column chromatography
on silica gel (100–200 mesh) using pet ether–ethyl acetate as eluent
to give pure pyrazole 6aa (yield 76%, 0.224 g). Otherderivatives were
prepared in a similar manner. Compounds 6aa–ac, 6ca, 6cc, 6da are
reported while others are new.
4.2.13. 1-(4-Methoxyphenyl)-3-(2-thienyl)-2,3-ditosyloxypropanone
(2cf). IR (nmax, in KBr): 1680 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
300 MHz,
d
): 2.42 (s, 3H, CH3); 2.44 (s, 3H, CH3); 3.83 (s, 3H, OCH3);
4.3.1. 4-(4-Bromophenyl)-1,5-diphenylpyrazole (6ae). IR (nmax, in
5.31 (d, 1H, CH, J¼8.1 Hz); 6.83 (dd, 1H, CH, J¼3.6 Hz); 6.85 (d, 1H,
CH, J¼3.6 Hz); 7.01 (d, 1H, CH, J¼8.1 Hz); 7.16 (d, 1H, CH, J¼3.6 Hz);
7.17–7.27 (m, 4H, ArH); 7.46–7.60 (m, 4H, ArH); 7.67–7.77 (m, 4H,
ArH). Elemental analysis: Calculated for C28H26O8S3; C 57.34, H
4.44; Found C 58.27, H 5.12.
KBr): No peak in CO region 1H NMR (CDCl3, 300 MHz,
d): 7.02–7.05
(m, 2H); 7.18–7.23 (m, 4H); 7.25–7.29 (m, 5H); 7.32–7.34 (m, 3H);
7.9 (s, 1H, C3–H). Elemental analysis: Calculated for C21H15N2Br; C
67.0, H 3.9, N 7.4; Found C 66.8, H 3.4, N 7.1.
4.3.2. 1,5-Diphenyl-4-(2-thienyl)pyrazole (6af). IR (nmax, in KBr): No
4.2.14. 1-(4-Methoxyphenyl)-3-(3-methyl-2-thienyl)-2,3-ditosyloxy-
peak in CO region 1H NMR (CDCl3, 300 MHz,
d): 6.87 (d, 1H, CH,
J¼3.6 Hz); 6.90(dd,1H, CH, J¼3.6 Hz); 7.15 (d,1H, CH, J¼3.6 Hz); 7.28–
7.38 (m, 10H, ArH); 7.95 (s, 1H, C3–H). Elemental analysis: Calculated
for C19H14N2S; C 75.49, H 4.63, N 9.27; Found C 75.65, H 5.16, N 9.72.
propanone (2cg). IR (nmax, in KBr): 1680 cmꢀ1 (CO stretch) 1H NMR
(CDCl3, 300 MHz, d): 2.19 (s, 3H, CH3); 2.43 (s, 3H, CH3); 2.44 (s, 3H,
CH3); 3.84 (s, 3H, OCH3); 5.36 (d, 1H, CH, J¼8.1 Hz); 6.64 (d, 1H, CH,
J¼5.1 Hz); 7.01 (d, 1H, CH, J¼8.1 Hz); 7.10 (d,1H, CH, J¼5.1 Hz); 7.21–
7.31 (m, 4H, ArH); 7.45–7.56 (m, 4H, ArH); 7.69–7.72 (m, 4H, ArH).
Elemental analysis: Calculated for C29H28O8S3; C 58.00, H 4.67;
Found C 58.72, H 4.70.
4.3.3. 4-(3-Methyl-2-thienyl)-1,5-diphenylpyrazole (6ag). IR (nmax
,
in KBr): No peak in CO region 1H NMR (CDCl3, 300 MHz,
d): 1.96 (s,
3H, CH3); 6.83 (d, 1H, CH, J¼5.1 Hz); 7.15 (d, 1H, CH, J¼5.1 Hz); 7.23–
7.33 (m,10H, ArH); 7.84 (s,1H, C3–H). Elemental analysis: Calculated
for C20H16N2S; C 75.95, H 5.06, N 8.86; Found C 76.00, H 5.13, N 9.23.
4.2.15. 1-(4-Chlorophenyl)-3-phenyl-2,3-ditosyloxypropanone
(2da)4. IR (nmax, in KBr): 1682 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
300 MHz,
d
): 2.42 (s, 3H, CH3); 2.43 (s, 3H, CH3); 4.9 (d, 1H, CH,
4.3.4. 4,5-Di(4-methylphenyl)-1-phenylpyrazole (6bb). IR (nmax, in
J¼8.1 Hz); 6.9 (d, 1H, CH, J¼8.1 Hz); 7.01–7.15 (m, 6H, ArH); 7.26–
7.28 (m, 5H, ArH); 7.42–7.45 (m, 2H, ArH); 7.61–7.64 (m, 2H, ArH);
7.77–7.80 (m, 2H, ArH). Elemental analysis: Calculated for
C29H25O7S2Cl; C 59.5, H 4.2; Found C 59.4, H 4.0.
KBr): No peak in CO region 1H NMR (CDCl3, 300 MHz,
d): 2.19 (s, 3H,
CH3);2.20(s, 3H, CH3);7.15–7.20(m, 4H);7.23–7.28(m, 3H);7.30–7.34
(m, 4H); 7.35–7.37 (m, 2H); 7.87 (s, 1H, C3–H). Elemental analysis:
Calculated for C23H20N2; C 85.2, H 6.2, N 8.6; Found C 84.9, H 6.1, N 8.3.
4.2.16. 1-(4-Chlorophenyl)-3-(2-thienyl)-2,3-ditosyloxypropanone
4.3.5. 5-(4-Methylphenyl)-1-phenyl-4-(2-thienyl)pyrazole (6bf). IR
(2df). IR (nmax, in KBr): 1674 cmꢀ1 (CO stretch) 1H NMR (CDCl3,
( d):
nmax, in KBr): No peak in CO region 1H NMR (CDCl3, 300 MHz,
300 MHz,
d
): 2.42 (s, 3H, CH3); 2.46 (s, 3H, CH3); 5.31 (d, 1H, CH,
2.37 (s, 3H, CH3); 6.86 (d, 1H, CH, J¼3.6 Hz); 6.88 (dd, 1H, CH,
J¼3.6 Hz); 7.11 (d, 1H, CH, J¼3.6 Hz); 7.21–7.31 (m, 9H, ArH); 7.91 (s,
1H, C3–H). Elemental analysis: Calculated for C20H16N2S; C 75.95, H
5.06, N 8.86; Found C 76.02, H 5.26, N 8.92.
J¼8.1 Hz); 6.83 (dd, 1H, CH, J¼3.6 Hz); 6.85 (d, 1H, CH, J¼3.6 Hz);
7.01 (d, 1H, CH, J¼8.1 Hz); 7.14 (d, 1H, CH, J¼3.6 Hz); 7.31 (d, 2H,
ArH, J¼8.4 Hz); 7.17–7.27 (m, 4H, ArH); 7.53 (d, 2H, ArH, J¼8.4 Hz);
7.67–7.78 (m, 4H, ArH). Elemental analysis: Calculated for
C27H23O7S3Cl; C 54.82, H 3.89; Found C 55.32, H 4.27.
4.3.6. 5-(4-Methylphenyl)-4-(3-methyl-2-thienyl)-1-phenylpyrazole
(6bg). IR (nmax, in KBr): No peak in CO region 1H NMR (CDCl3,
4.2.17. 1-(4-Chlorophenyl)-3-(3-methyl-2-thienyl)-2,3-ditosylox-
300 MHz, d): 1.97 (s, 3H, CH3); 2.33 (s, 3H, CH3); 6.83 (d, 1H, CH,
ypropanone (2dg). IR (nmax, in KBr): 1674 cmꢀ1 (CO stretch) 1H NMR
J¼5.1 Hz); 6.98 (d, 2H, ArH, J¼8.1 Hz); 7.05 (d, 2H, ArH, J¼8.1 Hz);
7.14 (d, 1H, CH, J¼5.1 Hz); 7.30–7.37 (m, 5H, ArH); 7.82 (s, 1H, C3–H).
Elemental analysis: Calculated for C21H18N2S; C 76.36, H 5.45, N
8.48; Found C 76.67, H 5.52, N 8.57.
(CDCl3, 300 MHz, d): 2.19 (s, 3H, CH3); 2.42 (s, 3H, CH3); 2.43 (s, 3H,
CH3); 5.36 (d, 1H, CH, J¼8.1 Hz); 6.64 (d, 1H, CH, J¼5.1 Hz); 7.01 (d,
1H, CH, J¼8.1 Hz); 7.10 (d, 1H, CH, J¼5.1 Hz); 7.23–7.31 (m, 4H, ArH);
7.33 (d, 2H, ArH, J¼8.4 Hz); 7.57 (d, 2H, ArH, J¼8.4 Hz); 7.72–7.73
(m, 4H, ArH). Elemental analysis: Calculated for C28H25O7S3Cl; C
55.62, H 4.13; Found C 56.20, H 4.39.
4.3.7. 5-(4-Methylphenyl)-4-(5-methyl-2-thienyl)-1-phenylpyrazole
(6bh). IR (nmax, in KBr): No peak in CO region 1H NMR (CDCl3,
300 MHz, d): 2.37 (s, 3H, CH3); 2.41 (s, 3H, CH3); 6.57 (d, 1H, CH,
4.2.18. 1-(4-Chlorophenyl)-3-(5-methyl-2-thienyl)-2,3-ditosyloxy-
J¼3.6 Hz); 6.65 (d, 1H, CH, J¼3.6 Hz); 6.98 (d, 2H, ArH, J¼8.1 Hz);
7.05 (d, 2H, ArH, J¼8.1 Hz); 7.30–7.37 (m, 5H, ArH); 7.85 (s, 1H, C3–
H). Elemental analysis: Calculated for C21H18N2S; C 76.36, H 5.45, N
8.48; Found C 76.52, H 5.54, N 8.75.
propanone (2dh). IR (nmax, in KBr): 1675 cmꢀ1 (CO stretch) 1H NMR
(CDCl3, 300 MHz, d): 2.35 (s, 3H, CH3); 2.43 (s, 3H, CH3); 2.44 (s, 3H,
CH3); 5.14 (d, 1H, CH, J¼8.1 Hz); 6.45 (d, 1H, CH, J¼3.3 Hz); 6.66 (d,
1H, CH, J¼3.3 Hz); 6.88 (d, 1H, CH, J¼8.1 Hz); 7.21–7.28 (m, 4H,
ArH); 7.33 (d, 2H, ArH, J¼8.4 Hz); 7.57 (d, 2H, ArH, J¼8.4 Hz); 7.69–
7.76 (m, 4H, ArH). Elemental analysis: Calculated for C28H25O7S3Cl;
C 55.62, H 4.13; Found C 56.30, H 4.79.
4.3.8. 5-(4-Methoxyphenyl)-1-phenyl-4-(2-thienyl)pyrazole
(6cf). IR (nmax, in KBr): No peak in CO region 1H NMR (CDCl3,
300 MHz,
d
): 3.82 (s, 3H, OCH3); 6.86 (d, 1H, CH, J¼3.6 Hz); 6.88 (d,
2H, ArH, J¼8.1 Hz); 6.89 (dd, 1H, CH, J¼3.6 Hz); 7.13 (d, 2H, ArH,
J¼8.1 Hz); 7.15 (d, 1H, CH, J¼3.6 Hz); 7.25–7.27 (m, 5H, ArH); 7.91 (s,
1H, C3–H). Elemental analysis: Calculated for C20H16N2SO; C 72.29,
H 4.82, N 8.43; Found C 72.20, H 5.16, N 8.55.
4.3. Synthesis of 4,5-diaryl-1-phenylpyrazoles 6
General procedure: A mixture of chalcone ditosylate (2aa, 0.550 g,
0.001 mol) and phenylhydrazine hydrochloride (0.29 g, 0.002 mol)
in dimethylformamide (25 mL) was refluxed for about 3 h. The re-
action mixture was then poured onto ice-cold water. Resulting
4.3.9. 5-(4-Methoxyphenyl)-4-(3-methyl-2-thienyl)-1-phenyl-
pyrazole (6cg). IR (nmax, in KBr): No peak in CO region 1H NMR

10180
O. Prakash et al. / Tetrahedron 65 (2009) 10175–10181
(CDCl3, 300 MHz,
d): 1.98 (s, 3H, CH3); 3.81 (s, 3H, OCH3); 6.78 (d,
1H NMR (CDCl3, 300 MHz,
d): 5.72 (s, 2H, CONH2); 7.06 (d, 2H, ArH,
2H, ArH, J¼8.1 Hz); 6.83 (d, 1H, CH, J¼5.1 Hz); 7.02 (d, 2H, ArH,
J¼8.1 Hz); 7.15 (d, 1H, CH, J¼5.1 Hz); 7.31–7.38 (m, 5H, ArH); 7.82 (s,
1H, C3–H). Elemental analysis: Calculated for C21H18N2SO; C 72.83,
H 5.20, N 8.09; Found C 73.30, H 5.21, N 8.21.
J¼8.1 Hz); 7.12 (d, 2H, ArH, J¼8.1 Hz); 7.31–7.34 (m, 5H, ArH); 7.64
(s, 1H, C3–H). Elemental analysis: Calculated for C16H12N3OBr; C
56.14, H 3.51, N 12.28; Found C 56.78, H 4.28, N 13.28.
4.4.5. 5-(4-Chlorophenyl)-4-phenylpyrazole-1-carboxamide (7da).
IR (nmax, in KBr): 1675 cmꢀ1 (CO stretch), 3372 cmꢀ1 (NH stretch)
4.3.10. 5-(4-Chlorophenyl)-1-phenyl-4-(2-thienyl)pyrazole (6df). IR
(
nmax, in KBr): No peak in CO region 1H NMR (CDCl3, 300 MHz,
d
):
1H NMR (CDCl3, 300 MHz,
d): 5.45 (s, 2H, CONH2); 7.14 (d, 2H, ArH,
6.88 (d, 1H, CH, J¼3.6 Hz); 6.96 (dd, 1H, CH, J¼3.6 Hz); 7.17 (d, 1H,
CH, J¼3.6 Hz); 7.19 (d, 2H, ArH, J¼8.1 Hz); 7.26 (d, 2H, ArH,
J¼8.1 Hz); 7.27–7.28 (m, 5H, ArH); 7.94 (s, 1H, C3–H). Elemental
analysis: Calculated for C19H13N2SCl; C 67.86, H 3.86, N 8.33; Found
C 67.86, H 4.12, N 8.62.
J¼8.1 Hz); 7.23 (d, 2H, ArH, J¼8.1 Hz); 7.29–7.33 (m, 5H, ArH); 7.64
(s, 1H, C3–H). Elemental analysis: Calculated for C16H12N3OCl; C
64.64, H 4.04, N 14.14; Found C 65.32, H 4.84, N 14.94.
4.5. Synthesis of 4,5-diarylpyrazole-1-thiocarboxamides 8
4.3.11. 5-(4-Chlorophenyl)-4-(3-methyl-2-thienyl)-1-phenylpyrazole
General procedure: A mixture of chalcone ditosylate (2aa,
0.550 g, 0.001 mol) and thiosemicarbazide (0.136 g, 0.0015 mol) in
ethanol (30 mL) was refluxed for 2–3 h. The reaction mixture was
then poured onto ice-cold water. Resulting mixture was extracted
with dichloromethane in three portions (3ꢂ50 mL). The organic
extract was dried over anhydrous sodium sulfate and filtered.
Evaporation of dichloromethane in vacuo gave the crude product,
which was purified by column chromatography on silica gel (100–
200 mesh) using pet ether–ethyl acetate as eluent to give pure
pyrazole 8aa (61%, 0.170 g). Other derivatives were prepared in
similar manner.
(6dg). IR (nmax, in KBr): No peak in CO region 1H NMR (CDCl3,
300 MHz,
d
): 1.96 (s, 3H, CH3); 6.84 (d,1H, CH, J¼5.1 Hz); 7.03 (d, 2H, ArH,
J¼8.1 Hz); 7.17 (d, 1H, CH, J¼5.1 Hz); 7.23 (d, 2H, ArH, J¼8.1 Hz); 7.29–
7.35 (m, 5H, ArH); 7.81 (s, 1H, C3–H). Elemental analysis: Calculated for
C20H15N2SCl; C 68.57, H 4.28, N 8.00; Found C 68.40, H 4.35, N 8.20.
4.3.12. 5-(4-Chlorophenyl)-4-(5-methyl-2-thienyl)-1-phenylpyrazole
(6dh). IR (nmax, in KBr): No peak in CO region 1H NMR (CDCl3,
300 MHz,
d
): 2.42 (s, 3H, CH3); 6.58 (d, 1H, CH, J¼3.6 Hz); 6.59 (d,
1H, CH, J¼3.6 Hz); 7.03 (d, 2H, ArH, J¼8.1 Hz); 7.23 (d, 2H, ArH,
J¼8.1 Hz); 7.29–7.35 (m, 5H, ArH); 7.85 (s, 1H, C3–H). Elemental
analysis: Calculated for C20H15N2SCl; C 68.57, H 4.28, N 8.00; Found
C 68.40, H 4.28, N 8.16.
4.5.1. 4,5-Diphenylpyrazole-1-thiocarboxamide (8aa). IR (nmax, in
KBr): 3295 cmꢀ1 (NH stretch) 1H NMR (CDCl3, 300 MHz,
d): 6.34 (s,
2H, CSNH2);7.24–7.28 (m, 5H, ArH);7.34–7.38 (m, 2H, ArH); 7.55–7.59
(m, 3H, ArH); 7.78 (s, 1H, C3–H). Elemental analysis: Calculated for
C16H13N3S; C 68.82, H 4.66, N 15.05; Found C 69.24, H 5.12, N 16.36
4.4. Synthesis of 4,5-diarylpyrazole-1-carboxamides 7
General procedure: A mixture of chalcone ditosylate (2aa,
0.550 g, 0.001 mol), semicarbazide hydrochloride (0.167 g,
0.0015 mol) and sodium acetate (0.123 g, 0.0015 mol) in ethanol
(30 mL) was refluxed for 2–3 h. The reaction mixture was then
poured onto ice-cold water and extracted with dichloromethane in
three portions (3ꢂ50 mL). The organic extract was dried over an-
hydrous sodium sulfate and filtered. Evaporation of dichloro-
methane in vacuo gave the crude product, which was purified by
column chromatography on silica gel (100–200 mesh) using pet
ether–ethyl acetate as eluent to afford pure pyrazole 7aa (62%,
0.163 g). Other derivatives were prepared in similar manner.
4.5.2. 4-(4-Methylphenyl)-5-phenylpyrazole-1-thiocarboxamide
(8ab). IR (nmax, in KBr): 3265 cmꢀ1 (NH stretch) 1H NMR (CDCl3,
300 MHz, d): 2.38 (s, 3H, CH3); 5.45 (s, 2H, CSNH2); 7.14 (d, 2H, ArH,
J¼8.1 Hz); 7.26 (d, 2H, ArH, J¼8.1 Hz); 7.49–7.58 (m, 5H, ArH); 7.69
(s, 1H, C3–H). Elemental analysis: Calculated for C17H15N3S; C 69.62,
H 5.12, N 14.33; Found C 70.14, H 6.23, N 15.31
4.5.3. 4-(4-Methoxyphenyl)-5-phenylpyrazole-1-thiocarboxamide
(8ac). IR (nmax, in KBr): 3265 cmꢀ1 (NH stretch) 1H NMR (CDCl3,
300 MHz, d): 3.84 (s, 3H, OCH3); 5.02 (s, 2H, CSNH2); 6.91 (d, 2H,
ArH, J¼8.1 Hz); 7.26 (d, 2H, ArH, J¼8.1 Hz); 7.39–7.41 (m, 3H, ArH);
7.51–7.52 (m, 2H, ArH); 7.67 (s, 1H, C3–H). Elemental analysis:
Calculated for C17H15N3OS; C 66.02, H 4.85, N 13.59; Found C 67.18,
H 5.25, N 14.67.
4.4.1. 4,5-Diphenylpyrazole-1-carboxamide (7aa). IR (nmax, in KBr,
cmꢀ1): 1675 (CO stretch), 3390 (NH stretch) 1H NMR (CDCl3,
300 MHz, d): 6.93 (s, 2H, CONH2); 7.25–7.34 (m, 4H, ArH); 7.44–7.48
(m, 6H, ArH); 7.68 (s, 1H, C3–H). Elemental analysis: Calculated for
C16H13N3O; C 73.00, H 4.94, N 15.96; Found C 73.65, H 5.34, N 16.29.
4.5.4. 5-(4-Chlorophenyl)-4-phenylpyrazole-1-thiocarboxamide
(8da). IR (nmax, in KBr): 3271 cmꢀ1 (NH stretch) 1H NMR (CDCl3,
4.4.2. 4-(4-Methylphenyl)-5-phenylpyrazole-1-carboxamide
300 MHz,
d
): 5.32 (s, 2H, CSNH2); 7.23 (d, 2H, ArH, J¼8.1 Hz); 7.32 (d,
(7ab). IR (nmax, in KBr, cmꢀ1): 1678 (CO stretch), 3378 (NH stretch)
2H, ArH, J¼8.1 Hz); 7.38–7.40 (m, 3H, ArH); 7.44–7.46 (m, 2H, ArH);
7.72 (s, 1H, C3–H). Elemental analysis: Calculated for C16H12N3SCl; C
61.34, H 3.83, N 13.42; Found C 62.30, H 4.26, N 13.58.
1H NMR (CDCl3, 300 MHz,
d): 2.38 (s, 3H, CH3); 5.65 (s, 2H, CONH2);
7.14 (d, 2H, ArH, J¼8.1 Hz); 7.28–7.38 (m, 5H, ArH); 7.40 (d, 2H, ArH,
J¼8.1 Hz); 7.69 (s, 1H, C3–H). Elemental analysis: Calculated for
C17H15N3O; C 73.65, H 5.41, N 15.16; Found C 74.28, H 5.58, N 15.92.
Acknowledgements
4.4.3. 4-(4-Methoxyphenyl)-5-phenylpyrazole-1-carboxamide
We are thankful to Council for Scientific and Industrial Research
(CSIR), New Delhi (Grant No CSIR 01(2186)/07/EMR-II) for financial
support of this work.
(7ac). IR (nmax, in KBr, cmꢀ1): 1665 (CO stretch), 3380 (NH stretch)
1H NMR (CDCl3, 300 MHz,
d): 3.77 (s, 3H, OCH3); 4.69 (s, 2H,
CONH2); 7.12 (d, 2H, ArH, J¼8.1 Hz); 7.31–7.46 (m, 5H, ArH); 7.50 (d,
2H, ArH, J¼8.1 Hz); 7.62 (s, 1H, C3–H). Elemental analysis: Calcu-
lated for C17H15N3O2; C 69.62, H 5.12, N 14.33; Found C 70.14, H
6.22, N 15.12.
References and notes
1. For review see: (a) Moriarty, R. M.; Vaid, R. K.; Koser, G. F. Synlett 1990, 365; (b)
Prakash, O.; Saini, N.; Sharma, P. K. Heterocycles 1994, 38, 409; (c) Koser, G. F.
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