untitled


European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	

	
European	Journal	of	Chemistry	

ISSN	2153‐2249	(Print)	/	ISSN	2153‐2257	(Online)		2011	EURJCHEM	
DOI:10.5155/eurjchem.2.2.223‐228.336	

	
	

	

	

European	Journal	of	Chemistry	
Journal	homepage:	www.eurjchem.com	

	 	 	

A	novel	and	efficient	approach	for	the	synthesis	of	new	halo	substituted	
2‐arylpyrazolo[4,3‐c]	coumarin	derivatives	

Pradeep	Lokhande*,	Kamal	Hasanzadeh	and	Shankaraiah	Guruvaiah	Konda	

Department	of	Chemistry,	Organic	Research	Chemistry,	University	of	Pune,	Pune‐411007,	India	

*Corresponding	author	at:	Department	of	Chemistry,	Organic	Research	Chemistry,	University	of	Pune,	Pune‐411007,	India.	Tel.:	+91.9604736297;		
fax:	+91.2025691728.	E‐mail	address:	pdlokhande@chem.unipune.ac.in	(P.	Lokhande).	

	
	

	 	

	 	 	
ARTICLE	INFORMATION	 	 ABSTRACT
Received:	20	November	2010	
Received	in	revised	form:	08	February	2011	
Accepted:	17	February	2011	
Online:	30	June	2011	

KEYWORDS	

	 A	 convenient	 protocol	 for	 the	 efficient	 synthesis	 of	 2‐arylpyrazolo[4,3‐c]coumarins	 is
described.	The	synthesis	route	involves	molecular	iodine	catalyzed	oxidative	cyclization	of	1‐
phenyl‐3‐(2'‐hydroxyaryl)‐4‐formyl	 pyrazoles	 in	 dimethylsulfoxide.	 During	 the	 lactonisation
of	 4‐formylpyrazoles,	 we	 found	 that	 iodine	 was	 incorporated	 into	 the	 unsubstituted	 O/P
position	 of	 the	 3‐(2'‐hydroxyaryl)	 group.	 Under	 similar	 conditions	 o‐allyloxy	 derivative	 of
pyrazoles	 gave	 same	 corresponding	 lactone	 derivatives	 by	 deallylation,	 lactonisation,	 and
iodination	in	one	step.	

Iodine	
Lactonisation	
Deallylation	
2‐Arylpyrazolo[4,3‐c]coumarins	
Oxidation	
Iodination	

	
1.	Introduction	
	

The	 diverse	 biological	 activities	 of	 natural	 and	 synthetic	
coumarins	 as	 coagulants	 [1]	 and	 antithrombotics	 [2]	 are	well	
known.	Some	of	the	coumarins	are	reported	as	anti	HIV	agents	
[3]	and	antioxidants	[4].	Many	coumarin	derivatives	are	known	
as	 free	radical	scavengers	[5].	Recent	work	demonstrated	 that	
novobiocin	was	observed	to	be	a	DNA‐gyrase	inhibitor	[6]	that	
binds	to	the	C‐terminal	nucleotide	binding	region	of	heat	shock	
protein‐90	[7].	They	have	also	found	to	posses	vasorelaxant	[8],	
anti‐inflammatory	 [9]	 and	 antitumor	 [10]	 activity.	 The	
incorporation	 of	 a	 fused	 heterocyclic	 moiety	 in	 parent	
coumarin	 alters	 its	 properties	 and	 converts	 it	 into	 important	
derivatives	 [11,12].	 Large	 numbers	 of	 heterocyclic	 fused	 and	
heterocyclic	substituted	coumarin	derivatives	is	used	as	drugs	
and	dyes	[13,14].	

The	 literature	 reports	 a	 short	 number	 of	 synthetic	 routes	
for	 2‐arylpyrazolo[4,3‐c]coumarins	 (2‐arlychromeno[4,3‐
c]pyrazol‐4(2H)‐ones),	such	as	cyclization	of	the	3‐hydrazone‐
4‐chloro	 or	 4‐hydroxy	 coumarins,	 which	 were	 relatively	
unstable	 and	 give	 a	 mixture	 of	 isomeric	 1‐aryl	 and	 2‐
arylpyrazolo[4,3‐c]coumarins	 [15,16].	These	compounds	were	
studied	 for	 binding	 studies	 interaction	 with	 the	 central	
benzodiazepine	receptor	[17].		

Considering	 the	 activity	 profile	 of	 the	 2‐arylpyrazolo[4,3‐
c]coumarins,	 we	 decided	 to	 synthesis	 a	 new	 series	 of	 halo	
substituted	 2‐arylpyrazolo[4,3‐c]coumarin	 derivatives.	 In	 this	
account,	we	describe	a	new	synthetic	route	for	the	synthesis	of	
the	 title	 compounds	 from	 the	 corresponding	 3‐(2‐
hydroxyaryl)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehydes	 (3)	 and	
3‐(2‐(allyloxyaryl)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehydes	 (4)	
by	 using	 iodine	 in	 dimethylsulfoxide.	 The	 use	 of	 iodine	 for	
synthetic	 purpose	 has	 gained	 significant	 importance.	 The	
negligible	 toxicity	 associated	with	 iodine,	 in	 conjunction	with	

ease	of	handling,	readily	availability,	low	cost	and	mild	reaction	
conditions	 employed	 has	 resulted	 in	 its	 application	 in	 an	
increasing	 number	 of	 diverse	 transformations	 [18‐28].	 In	
continuation	of	our	research	programme	using	I2/DMSO	as	an	
efficient	catalytic	system	for	oxidation	of	pyrazoline	to	pyrazole	
[29],	 deallylation	 and	 preparation	 of	 flavones	 from	 2'‐
allyloxychalcones	 [30]	 and	 oxidation	 of	 dihydroflavone	 [31],	
here,	 we	 wish	 to	 report	 some	 new	 halo	 substituted	 2‐
arylpyrazolo[4,3‐c]coumarins	under	mild	condition.	To	the	best	
of	our	knowledge,	 there	are	no	earlier	reports	 for	 I2/DMSO	as	
an	 efficient	 catalytic	 system	 for	 the	 synthesis	 of	 2‐
arylpyrazolo[4,3‐c]coumarins.	
	
2.	Experimental	
	
2.1.	Instrumentation	
	

	1H	NMR	 (300	MHz)	 and	 13C	NMR	 (75	MHz)	 spectra	were	
recorded	on	a	Varian	VXR	300	instrument	at	293	K	in	DMSO‐d6.	
Chemical	shift	values	were	recorded	in	δ	units	(ppm)	relative	to	
Me4Si	as	internal	standard.	Melting	points	were	determined	by	
using	 a	 Buchi	 melting	 point	 apparatus.	 Infrared	 spectra	 (IR)	
were	 recorded	 using	 KBr	 pellets	 on	 a	 Perkin‐Elmer	 240C	
analyzer.	 Mass	 spectra	 were	 recorded	 in	 an	 AE‐IMS‐30	
spectrometer.	 Thin	 layer	 chromatography	 (TLC)	 was	
performed	 on	 silica	 gel	 60	 PF254	 plates	 or	 aluminium	 oxide	
plates	 from	 Merck.	 Elemental	 analyses	 were	 performed	 on	 a	
Thermo	Flash	EA	1112	analyzer.	
	
2.2.	Synthesis	
	
2.2.1.	General	procedure	for	the	preparation	of	substituted	
acetophenones	(1a‐g)	
	



224	 Lokhande	et	al.	/	European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	
	

Parent	 5‐chloro‐2‐hydroxyacetophenone,	 5‐bromo‐2‐
hydroxyacetophenone,	 3‐chloro‐2‐hydroxyacetophenone,	 3,5‐
dichloro‐2‐hydroxyacetophenone,	 and	 5‐methyl‐2‐hydroxy‐
acetophenone	 were	 synthesized	 from	 p‐chloro,	 p‐bromo,	 o‐
chloro,	2,4‐dichloro	and	p‐cresol	phenols	respectively,	by	Fries‐
rearrangement	 using	 acetyl	 chloride	 and	 AlCl3	 [32].	 3,5‐
dibromo‐2‐hydroxyacetophenone	 and	 3‐bromo‐5‐methyl‐2‐
hydroxyacetophenone	 were	 also	 synthesized	 by	 the	
bromination	(bromine	in	acetic	acid)	method	[32].	
	
2.2.2.	General	procedure	for	the	preparation	of	phenyl	
hydrazones	(2a‐g)	
	

To	 a	 solution	 of	 the	 appropriate	 2‐hydroxyacetophenone	
derivatives	 (24	 mmol)	 in	 40	 mL	 methanol,	 phenyl	 hydrazine	
(24	mmol)	was	added	and	refluxed	for	two	hours.	After	cooling	
the	 reaction	 mixture	 the	 phenyl	 hydrazone	 derivatives	 was	
crystallized	and	filtered,	the	yield	was	91‐94	%.	

5‐Chloro‐2‐hydroxy	 acetophenone	 phenylhydrazone	 (2a):	
Yield:	91%.	M.p.:	169‐171	oC	(170	oC	[33]).	FT‐IR	(KBr,	,	cm‐1):	
3355,	1601.	1H	NMR	(300	MHz,	CDCl3):	2.30	(s,	3H),	6.93‐7.03	
(m,	4H),	7.16	(dd,	1H	J1	=	8.4	Hz,	J2	=	2.4	Hz),	7.29‐7.36	(m,	4H),	
12.49	 (s,	 1H).	 13C	 NMR	 (75	 MHz,	 CDCl3):	 16.2,	 115.4,	 118.3,	
119.8,	120.6,	128.1,	129.8,	130.5,	133.8,	145.1,	160.4,	170.1.	MS	
(EI,	 m/z):	 262	 (M+2),	 260	 (M+),	 243.	 Anal.	 Calcd.	 for	
C14H13N2OCl:	 C,	 64.61;	 H,	 5.00;	 N,	 10.76.	 Found:	 C,	 64.72;	 H,	
4.93;	N,	10.68%.	

5‐Bromo‐2‐hydroxy	 acetophenone	 phenylhydrazone	 (2b):	
Yield:	93%.	M.p.:	163‐164	oC	(164	oC	[33]).	FT‐IR	(KBr,	,	cm‐1):	
3358,	1600.	1H	NMR	(300	MHz,	CDCl3):	2.32	(s,	3H),	7.01	(d,	1H,	
J	=	7.5	Hz),	7.08‐7.12	(m,	3H),	7.21	(dd,	1H,	J1	=	7.8	Hz,	J2	=	2.7	
Hz),	7.24‐7.34	(m,	3H),	7.44	(d,	1H,	J	=	2.7	Hz),	12.61	(s,	1H).	13C	
NMR	(75	MHz,	CDCl3):	15.8,	114.9,	117.1,	119.4,	119.8,	121.5,	
128.2,	 136.3,	 137.1,	 145.4,	 159.2,	 168.2.	 MS	 (EI,	 m/z):	 306	
(M+2),	304	(M+).	Anal.	Calcd.	for	C14H13N2OBr:	C,	55.26;	H,	4.27;	
N,	9.21.	Found:	C,	55.31;	H,	4.22;	N,	9.11%.	

3‐Chloro‐2‐hydroxyacetophenone	 phenylhydrazone	 (2c):	
Yield:	92%.	M.p.:	146‐148	oC.	FT‐IR	(KBr,	,	cm‐1):	3325,	1601.	
1H	NMR	(300	MHz,	CDCl3):	2.34	(s,	3H),	6.81	(t,	1H,	J	=	8.1	Hz),	
6.94	 (t,	1H,	 J	 =	7.2	Hz),	 7.31	 (d,	 2H,	 J	=	8.1	Hz),	7.27‐7.33	 (m,	
4H),	12.63	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	16.1,	115.3,	119.2,	
120.3,	122.8,	125.6,	129.7,	129.8,	134.5,	144.2,	158.6,	169.3.	MS	
(EI,	m/z):	262	(M+2),	260	(M+).	Anal.	Calcd.	for	C14H13N2OCl:	C,	
64.61;	H,	5.00;	N,	10.76.	Found:	C,	64.56;	H,	4.94;	N,	10.81%.	

3,5‐Dichloro‐2‐hydroxy	 acetophenone	 phenylhydrazone	
(2d):	Yield:	93%.	M.p.:	132‐134	oC	(133	oC	[15]).	FT‐IR	(KBr,	,	
cm‐1):	3344,	1604.	1H	NMR	(300	MHz,	CDCl3):	2.33	(s,	3H),	6.96	
(t,	1H,	 J	 =	7.5	Hz),	 7.02	 (d,	 2H,	 J	 =	7.5	Hz),	 7.28‐7.33	 (m,	4H),	
7.39	(d,	1H,	J	=	2.1	Hz),	13.18	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	
15.9,	 115.9,	 119.8,	 122.0,	 126.7,	 129.3,	 129.5,	 129.8,	 135.6,	
144.8,	 157.8,	 168.8.	 MS	 (EI,	 m/z):	 296	 (M+2),	 294(M+).	 Anal.	
Calcd.	 for	 C14H12N2OCl2:	 C,	 57.14;	 H,	 4.08;	 N,	 9.52.	 Found:	 C,	
57.27;	H,	4.11;	N,	9.61%.	

3,5‐Dibromo‐2‐hydroxy	 acetophenone	 phenylhydrazone	
(2e):	Yield:	93%.	M.p.:	151‐152	oC.	FT‐IR	(KBr,	,	 cm‐1):	3358,	
1608.	1H	NMR	(300	MHz,	CDCl3):	2.34	(s,	3H),	6.99	(t,	1H,	J	=	8.1	
Hz),	7.09	(d,	2H,	J	=	7.1	Hz),	7.31	(s,	1H),	7.32‐7.36	(m,	3H),	7.48	
(d,	1H,	J	=	2.4	Hz),	12.87	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	16.1,	
115.9,	 116.0,	 119.1,	 119.4,	 124.2,	 128.1,	 134.2,	 139.3,	 143.9,	
159.1,	 169.2.	 MS	 (EI,	 m/z):	 386	 (M+4),	 384	 (M+2),	 382(M+).	
Anal.	Calcd.	for	C14H12N2OBr2:	C,	43.97;	H,	3.14;	N,	7.32.	Found:	
C,	44.08;	H,	3.20;	N,	7.42%.	

3‐Bromo‐5‐chloro‐2‐hydroxy	acetophenone	phenylhydrazone	
(2f):	 Yield:	 93%.	M.p.:	144‐145	oC.	 FT‐IR	 (KBr,	,	 cm‐1):	3346,	
1599.	1H	NMR	(300	MHz,	CDCl3):	2.32	(s,	3H),	6.98	(t,	1H,	J	=	7.2	
Hz),	7.04	(d,	2H,	J	=	7.2	Hz),	7.29	(s,	1H),	7.32‐7.34	(m,	3H),	7.47	
(d,	1H,	J	=	2.4	Hz),	13.36	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	15.8,	
114.1,	 116.3,	 118.1,	 120.0,	 128.2,	 128.3,	 128.6,	 133.5,	 142,	
158.2,	 169.1.	MS	 (EI,	m/z):	 342	 (M+4),	 340	 (M+2),	 338	 (M+).	

Anal.	Calcd.	for	C14H12N2OBrCl:	C,	49.70;	H,	3.55;	N,	8.28.	Found:	
C,	49.75;	H,	3.61;	N,	8.34%.	

3‐Bromo‐5‐methyl‐2‐hydroxy	 acetophenone	 phenyl	
hydrazone	(2g):	Yield:	93%.	M.p.:	171‐173	oC.	FT‐IR	(KBr,	,	cm‐

1):	3344,	1597.	1H	NMR	(300	MHz,	CDCl3):	2.29	(s,	3H),	2.32	(s,	
3H),	6.95	 (t,	1H,	 J	=	7.5	Hz),	7.04	 (d,	2H,	8.4	Hz),	7.16	 (s,	1H),	
7.26‐7.31	 (m,	 3H),	 7.32	 (d,	 1H,	 J	 =	 1.8	 Hz),	 13.17	 (s,	 1H).	 13C	
NMR	 (75	 MHz,	 CDCl3):	 16.1,	 22.9,	 112.6,	 115.8,	 117.0,	 122.1,	
128.3,	 128.9,	 134.0,	 138.2,	 142.4,	 157.7,	 169.4.	MS	 (EI,	 m/z):	
320	(M+2),	318	(M+).	Anal.	Calcd.	for	C15H15N2OBr:	C,	56.60;	H,	
4.71;	N,	8.80.	Found:	C,	56.71;	H,	4.67;	N,	8.69%.	
	
2.2.3.	General	procedure	for	the	preparation	of	3‐aryl‐1‐
phenyl‐1H‐pyrazole‐4‐carbaldehyde	(3a‐g)		
	

The	 derivatives	 of	 2‐hydroxyacetophenone	 phenyl	
hydrazone	(0.01	mol)	was	dissolved	in	DMF	(15	mL)	and	then	
POCl3	(0.03	mol)	was	added	drop	wise	at	0	oC.	After	a	complete	
addition	 of	 POCl3,	 the	 reaction	 mixture	 warmed	 at	 room	
temperature	 and	 heated	 at	 60‐70	 oC	 for	 2.5‐3	 h.The	 reaction	
was	 poured	 onto	 crushed	 ice	 and	 then	 neutralized	with	 10%	
aqueous	NaOH	 solution.	 The	 precipitate	was	 filtered,	 strongly	
washed	with	water	and	crystallized	from	ethanol. 

3‐(5‐chloro‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(3a):	Yield:	84%.	M.p.:	132‐134	oC.	FT‐IR	(KBr,	,	
cm‐1):	3450,	1683,	1657.	1H	NMR	(300	MHz,	CDCl3):	7.02	(d,	1H,	
J	=	8.4	Hz),	7.25	(dd,	1H,	J1	=	8.7	Hz,	J2	=	2.4	Hz),	7.43	(t,	1H,	J	=	
7.2	Hz),	7.54	(t,	2H,	J	=	7.8	Hz),	7.69	(d,	2H,	J	=	7.8	Hz),	8.07	(d,	
1H,	 J	 =	 2.1Hz),	 8.56	 (s,	 1H),	 10.14	 (s,	 2H).	 13C	NMR	 (75	MHz,	
CDCl3):	 116.4,	 118.5,	 119.3,	 122.8,	 124.2,	 128.4,	 129.0,	 129.7,	
130.6,	133.5,	137.6,	150.9,	154.4,	183.2.	MS	(EI,	m/z):	298	(M+).	
Anal.	Calcd.	for	C16H11N2O2Cl:	C,	64.42;	H,	3.69;	N,	9.39.	Found:	
C,	63.91;	H,	3.58;	N,	9.44%.	

3‐(5‐bromo‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(3b):	Yield:	86%.	M.p.:	133‐134	oC.	FT‐IR	(KBr,	,	
cm‐1):	3454,	1683,	1598.	1H	NMR	(300	MHz,	CDCl3):	7.01	(d,	1H,	
J	=	8.7	Hz),	7.42‐7.49	(m,	2H),	7.57	(t,	2H,	J	=	8.4Hz),	7.72	(d,	2H,	
J	=	8.4	Hz),	8.23	(s,	1H),	8.59	(s,	1H),	10.18	(s,	1H),	10.20	(s,	1H).	
13C	 NMR	 (75	 MHz,	 CDCl3):	 117.2,	 117.7,	 118.0,	 119.2,	 124.8,	
128.4,	131.2,	131.4,	133.7,	134.6,	141.8,	151.8,	153.6,	183.4.	MS	
(EI,	m/z):	342	(M+).	Anal.	Calcd.	 for	C16H11N2O2Br:	C,	56.14;	H,	
3.21;	N,	8.18.	Found:	C,	56.23;	H,	3.28;	N,	8.23%.	

3‐(3‐Chloro‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(3c):	Yield:	85%.	M.p.:	149‐150	oC.	FT‐IR	(KBr,	,	
cm‐1):	3448,	1693,	1664.	1H	NMR	(300	MHz,	CDCl3):	6.97	(t,	1H,	
J	=	7.8	Hz),	7.41‐7.45	(m,	2H),	7.53	(t,	2H,	 J	=	7.5	Hz),	7.71	(d,	
2H,	 J	=	8.1	Hz),	7.98	(d,	1H,	 J	=	7.8	Hz),	8.58	 (s,	1H),	10.13	(s,	
1H),	 10.65	 (s,	 1H).	 13C	 NMR	 (75	 MHz,	 CDCl3):	 116.6,	 119.2,	
119.5,	 121.9,	 123.0,	 128.2,	 128.4,	 129.8,	 131.2,	 133.4,	 137.7,	
151.4,	 151.7,	 183.5.	MS	 (EI,	 m/z):	 298	 (M+).	 Anal.	 Calcd.	 for	
C16H11N2O2Cl:	C,	64.42;	H,	3.69;	N,	9.39.	Found:	C,	64.65;	H,	3.74;	
N,	9.33%.	

3‐(3,5‐Dichloro‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(3d):	Yield:	88%.	M.p.:	166‐167	oC.	FT‐IR	(KBr,	,	
cm‐1):	3444,	1687,	1654.	1H	NMR	(300	MHz,	CDCl3):	7.44‐7.47	
(m,	2H),	7.54	(t,	2H,	J	=	7.5Hz),	7.70	(d,	2H,	J	=	7.5	Hz),	8.18	(s,	
1H),	8.54	(s,	1H),	10.11	(s,	1H),	10.79	(s,	1H).	13C	NMR	(75	MHz,	
CDCl3):	 117.4,	 119.5,	 122.7,	 123.2,	 124.4,	 127.9,	 128.8,	 130.0,	
130.8,	134.2,	137.7,	150.4,	150.8,	183.0.	MS	(EI,	m/z):	332	(M+).	
Anal.	Calcd.	for	C16H10N2O2Cl2:	C,	57.83;	H,	3.01;	N,	8.43.	Found:	
C,	57.76;	H,	3.02;	N,	8.58%.	

3‐(3,5‐dibromo‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(3e):	Yield:	87%.	M.p.:	172‐173	oC.	FT‐IR	(KBr,	,	
cm‐1):	3360,	1689,	1661.	1H	NMR	(300	MHz,	CDCl3):	7.49	(t,	1H,	
J	=	8.7Hz),	7.56	(t,	2H,	J	=	8.7	Hz),	7.72	(d,	2H,	J	=	8.4	Hz),	7.75	
(d,	1H,	J	=	2.4	Hz),	8.37	(d,	1H,	J	=	2.4	Hz),	8.60	(s,	1H),	10.14	(s,	
1H),	 10.96	 (s,	 1H).	 13C	 NMR	 (75	 MHz,	 CDCl3):	 116.4,	 117.1,	
117.4,	 121.3,	 127.2,	 128.4,	 131.5,	 132.1,	 135.8,	 136.4,	 141.9,	
151.6,	152.8,	183.8.	MS	(EI,	m/z):	424	(M+4),	422	(M+2),	420	



Lokhande	et	al.	/	European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	 225	
 

 
 

(M+).	Anal.	Calcd.	 for	C16H10N2O2Br2:	C,	45.71;	H,	2.38;	N,	6.66.	
Found:	C,	45.82;	H,	2.35;	N,	6.71%.	

3‐(3‐Bromo‐5‐chloro‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐
pyrazole‐4‐carbaldehyde	(3f):	Yield:	84%.	M.p.:	175‐176	oC.	FT‐
IR	(KBr,	,	cm‐1):	3344,	1685,	1649.	1H	NMR	(300	MHz,	CDCl3):	
7.48	(t,	1H,	J	=	7.2	Hz),	7.57	(t,	2H,	J	=	7.2	Hz),	7.59	(d,	1H,	J	=	2.4	
Hz),	7.74	(d,	2H,	J	=	7.2	Hz),	8.26	(d,	1H,	J	=	2.4	Hz),	8.61	(s,	1H),	
10.16	 (s,	 1H),	 10.96	 (s,	 1H).	 13C	NMR	 (75	MHz,	CDCl3):	 117.2,	
117.6,	 119.2,	 125.2,	 128.4,	 129.3,	 131.4,	 131.6,	 132.1,	 132.9,	
139.7,	152.5,	154.7,	184.1.	MS	(EI,	m/z):	380	(M+4),	376	(M+).	
Anal.	 Calcd.	 for	 C16H10N2O2BrCl:	 C,	 51.06;	 H,	 2.65;	 N,	 7.44.	
Found:	C,	51.15;	H,	2.60;	N,	7.51%.	

3‐(3‐Bromo‐5‐methyl‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐
pyrazole‐4‐carbaldehyde	(3g):	Yield:	85%.	M.p.:	159‐160	oC.	FT‐
IR	 (KBr,	,	 cm‐1):	3489	 (OH),	 1680,	 1645.	1H	NMR	 (300	MHz,	
CDCl3):	2.36	(s,	3H),	7.44‐7.46	(m,	2H),	7.54	(t,	2H,	J	=	7.2	Hz),	
7.72‐7.75	(m,	3H),	8.59	(s,	1H),	10.17	(s,	1H),	10.40	(s,	1H).	13C	
NMR	(75	MHz,	CDCl3):	22.8,	116.1,	115.5,	119.3,	123.7,	128.2,	
131.4,	132.1,	133.0,	134.7,	135.3,	141.2,	151.0,	151.8,	182.8.	MS	
(EI,	m/z):	358	(M+2),	356	(M+).	Anal.	Calcd.	for	C17H13N2O2Br:	C,	
57.30;	H,	3.65;	N,	7.85.	Found:	C,	57.49;	H,	3.71;	N,	7.93%.		
 
2.2.4.	General	procedure	for	the	preparation	of	3‐(2‐
(allyloxy	aryl)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde	(4a‐
g)	
	

To	 a	 solution	 of	 3‐aryl‐4‐formylpyrazole	 (3.5	 mmol)	 in	
DMSO	(10	mL),	K2CO3	(8	mmol)	and	ally	bromide	(3.55	mmol)	
was	 added.	 The	 reaction	 mixture	 was	 stirred	 at	 room	
temperature	for	4h.	Then	the	reaction	mixture	was	poured	onto	
crushed	 ice.	The	precipitation	was	 filtered	and	crystallized	by	
methanol.	

3‐(2‐(allyloxy)‐5‐chlorophenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(4a):	Yield:	87%.	M.p.:	121‐123	oC.	FT‐IR	(KBr,	,	
cm‐1):	1672,	1650.	 1H	NMR	(300	MHz,	CDCl3):	4.55	 (d,	2H,	 J	 =	
5.1	Hz),	5.24	(d,	1H,	J	=	10.8	Hz),	5.31	(d,	1H,	J	=	17.1	Hz),	5.93	
(m,	1H),	6.95	(d,	1H,	J	=	8.7	Hz),	7.36‐7.41	(m,	2H),	7.51	(t,	2H,	J	
=	8.4	Hz),	7.62	(d,	1H,	J	=	2.4	Hz),	7.77	(d,	2H,	J	=	8.7	Hz),	8.51	(s,	
1H),	9.82	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	69.5,	113.7,	118.0,	
119.4,	 122.3,	 123.2,	 126.1,	 127.7,	 129.1,	 129.5,	 130.2,	 130.9,	
132.0,	138.9,	150.4,	154.5,	185.9.	MS	(EI,	m/z):	338	(M+).	Anal.	
Calcd.	 for	 C19H15N2O2Cl:	 C,	 67.45;	 H,	 4.43;	 N,	 8.28.	 Found:	 C,	
67.58;	H,	4.31;	N,	8.35%.	

3‐(2‐(allyloxy)‐5‐bromophenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(4b):	Yield:	89%.	M.p.:	128‐129	oC.	FT‐IR	(KBr,	,	
cm‐1):	1675,	1658.	 1H	NMR	(300	MHz,	CDCl3):	4.58	 (d,	2H,	 J	 =	
5.4	Hz),	5.21	(d,	1H,	J	=	10.5	Hz),	5.40	(d,	1H,	J	=	17.4	Hz),	5.91	
(m,	1H),	6.88	(d,	1H,	J	=	8.7	Hz),	7.32‐7.41	(m,	2H),	7.50	(t,	2H,	J	
=	8.4	Hz),	7.74	(d,	1H,	J	=	2.4	Hz),	7.86	(d,	2H,	J	=	8.4	Hz),	8.53	(s,	
1H),	9.79	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	70.1,	112.3,	115.9,	
118.1,	 119.2,	 122.1,	 122.8,	 129.5,	 129.8,	 130.5,	 132.0,	 135.7,	
135.8,	140.3,	150.6,	155.3,	186.4.	MS	(EI,	m/z):	384	(M+2),	382	
(M+);	Anal.	 Calcd.	 for	C19H15N2O2Br:	 C,	 59.68;	H,	 3.92;	N,	 7.32.	
Found:	C,	60.08;	H,	4.09;	N,	7.18%.		

3‐(2‐(allyloxy)‐3‐chlorophenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(4c):	Yield:	88%.	M.p.:	92‐94	oC.	FT‐IR	(KBr,	,	cm‐

1):	1678,	1635.	1H	NMR	(300	MHz,	CDCl3):	4.32	(d,	2H,	J	=	6	Hz),	
5.01	(d,	1H,	J	=	10.5	Hz),	5.19	(d,	1H,	J	=	16.8	Hz),	5.82	(m,	1H),	
7.21	(t,	1H,	J	=	7.8	Hz),	7.42	(t,	1H,	J	=	7.5	Hz),	7.50‐7.57	(m,	4H),	
7.79	(d,	2H,	J	=	7.5	Hz),	8.54	(s,	1H),	9.85	(s,	1H).	13C	NMR	(75	
MHz,	 CDCl3):	 68.4,	 114.3,	 119.1,	 120.4,	 123.7,	 124.8,	 125.1,	
129.3,	 129.5,	 129.8,	 131.7,	 132.8,	 134.6,	 138.8,	 151.6,	 155.5,	
186.8.	MS	(EI,	m/z):	338	(M+).	Anal.	Calcd.	for	C19H15N2O2Cl:	C,	
67.45;	H,	4.43;	N,	8.28.	Found:	C,	67.15;	H,	4.39;	N,	8.31%.	

3‐(2‐(allyloxy)‐5,3‐dichlorophenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(4d):	Yield:	90%.	M.p.:	114‐116	oC.	FT‐IR	(KBr,	,	
cm‐1):	1674,	1598.	 1H	NMR	(300	MHz,	CDCl3):	4.28	 (d,	2H,	 J	 =	
5.7	Hz),	5.11	(d,	1H,	J	=	10.2	Hz),	5.18	(d,	1H,	J	=	17.4	Hz),	7.41	

(t,	1H,	 J	 =	7.2	Hz),	 7.51‐7.57	 (m,	4H),	7.78	 (d,	 2H,	 J	 =	7.5	Hz),	
8.54	(s,	1H),	9.84	(s,	1H).	13C	NMR	(75	MHz,	CDCl3):	70.1,	115.3,	
115.6,	 120.5,	 122.8,	 125.7,	 126.8,	 126.9,	 128.0,	 131.2,	 132.3,	
133.0,	136.8,	140.3,	151.2,	157.1,	188.2.	MS	(EI,	m/z):	372	(M+).	
Anal.	Calcd.	for	C19H14N2O2Cl2:	C,	61.29;	H,	3.76;	N,	7.52.	Found:	
C,	61.46;	H,	3.66;	N,	7.68%.	

3‐(2‐(allyloxy)‐5,3‐dibromophenyl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehyde	(4e):	Yield:	91%.	M.p.:	118‐120	oC.	FT‐IR	(KBr,	,	
cm‐1):	1681,	1601.	1H	NMR	(300	MHz,	CDCl3):	4.32	(d,	2H,	J	=	6	
Hz),	5.02	(d,	1H,	J	=	10.5	Hz),	5.24	(d,	1H,	J	=	17	Hz),	7.45	(t,	1H,	
J	=	7.5	Hz),	7.51	(d,	1H,	J	=	2.4	Hz),	7.53‐7.61	(m,	3H),	7.78	(d,	
2H,	 J	 =	 7.5	 Hz),	 8.54	 (s,	 1H),	 9.84	 (s,	 1H).	 13C	 NMR	 (75	MHz,	
CDCl3):	 68.8,	 112.0,	 115.4,	 118.4,	 120.2,	 122.3,	 126.4,	 128.9,	
130.0,	132.8,	135.7,	136.5,	137.1,	143.1,	149.7,	150.1,	184.3.	MS	
(EI,	 m/z):	 464	 (M+4),	 462	 (M+2),	 460	 (M+).	 Anal.	 Calcd.	 for	
C19H14N2O2Br2:	 C,	 49.56;	 H,	 3.04;	 N,	 6.08.	 Found:	 C,	 49.14;	 H,	
3.12;	N,	6.26%.	

3‐(2‐(allyloxy)‐3‐bromo‐5‐chlorophenyl)‐1‐phenyl‐1H‐
pyrazole‐4‐carbaldehyde	(4f):	Yield:	89%.	M.p.:	112‐114	oC.	FT‐
IR	(KBr,	,	cm‐1):	1669,	1604.	 1H	NMR	(300	MHz,	CDCl3):	4.31	
(d,	2H,	J	=	5.7	Hz),	5.14	(d,	1H,	J	=	10.4	Hz),	5.21	(d,	1H,	J	=	17.8		
Hz),	7.43	(t,	1H,	J	=	7.6	Hz),	7.53‐7.59	(m,	4H),	7.81	(d,	2H,	J	=	
7.8	Hz),	 8.59	 (s,	 1H),	 9.87	 (s,	 1H).	 13C	NMR	 (75	M	Hz,	 CDCl3):	
74.9,	 116.7,	 118.6,	 118.8,	 119.5,	 122.9,	 128.0,	 128.3,	 129.3,	
129.6,	 130.2,	 132.2,	 133.8,	 138.8,	 149.7,	 152.4,	 185.8.	MS	 (EI,	
m/z):	 420	 (M+4),	 418	 (M+2),	 416	 (M+).	 Anal.	 Calcd.	 for	
C19H14N2O2BrCl:	C,	 54.80;	H,	 3.36;	N,	6.73.	 Found:	C,	 55.03;	H,	
3.40;	N,	6.51%.	

3‐(2‐(allyloxy)‐3‐bromo‐5‐methylphenyl)‐1‐phenyl‐1H‐
pyrazole‐4‐carbaldehyde	(4g):	Yield:	91%.	M.p.:	102‐104	oC.	FT‐
IR	(KBr,	,	cm‐1):	1672,	1614.	 1H	NMR	(300	MHz,	CDCl3):	2.38	
(s,	3H),	4.24	(d,	2H,	J	=	6	Hz),	5.09	(d,	1H,	J	=	10.8	Hz),	5.18	(d,	
1H,	J	=	16.8	Hz),	5.81	(m,	1H),	7.40‐7.42	(m,	2H),	7.49‐7.54	(m,	
2H),	7.78	(d,	2H,	J	=	8.1	Hz),	8.53	(s,	1H),	9.84	(s,	1H).	13C	NMR	
(75	M	Hz,	CDCl3):	24.1,	69.3,	114.3,	115.1,	119.4,	119.8,	123.2,	
128.3,	 129.6,	 131.4,	 131.5,	 134.0,	 134.7,	 134.9,	 139.9,	 150.8,	
156.2,	184.8.	MS	(EI,	m/z):	398	(M+2),	396	(M+).	Anal.	Calcd.	for	
C20H17N2O2Br:	 C,	 60.60;	 H,	 4.29;	 N,	 7.07.	 Found:	 C,	 60.56;	 H,	
4.28;	N,	7.11%.	
	
2.2.5.	General	procedure	for	the	preparation	of	substituted	
of	2‐arylpyrazolo[4,3‐c]coumarin	derivatives	(5a‐g)	
	

To	 a	 solution	 of	 3‐(2‐hydroxyaryl)‐1‐phenyl‐1H‐pyrazole‐
4‐carbaldehydes	 (3a‐g)	 (1	 mmol)	 or	 3‐(2‐(allyloxyaryl)‐1‐
phenyl‐1H‐pyrazole‐4‐carbaldehydes	(4a‐g)	(1	mmol)	in	DMSO	
(10	 mL),	 iodine	 (10	 mol%)	 and	 4‐5	 drops	 of	 concentrated	
H2SO4	was	added.	Then	reaction	mixture	was	heated	at	120	oC.	
After	 the	 completion	 of	 the	 reaction	 (checked	 by	 TLC),	 the	
contents	were	cooled	to	room	temperature	and	poured	into	ice‐
cooled	water.	The	separated	solid	was	filtered	and	washed	with	
cooled	dilute	sodium	thiosulphate	solution.	Finally	the	obtained	
product	was	crystallized	from	DMF	to	give	product	5a‐g.	 

8‐chloro‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	 (5a):	
FT‐IR	(KBr,	,	cm‐1):	1734.	1H	NMR	(300	MHz,	DMSO‐d6):	7.35	
(d,	1H,	J	=	8.7	Hz,	C6‐H),	7.44‐7.50	(m,	2H,	C7‐H	&	Ph‐H),	7.57	(t,	
2H,	J	=	7.8	Hz,	Ph‐H),	7.84	(d,	2H,	J	=	8.4	Hz,	Ph‐H),	8.17	(d,	1H,	J	
=	2.7	Hz,	C9‐H),	8.69	(s,	1H,	C3‐H).	13C	NMR	(75	MHz,	DMSO‐d6):	
109.1,	 116.3,	 120.8,	 125.9,	 127.1,	 127.9,	 128.9,	 129.1,	 130.9,	
132.2,	140.2,	150.1,	150.9,	157.7.	MS	(EI,	m/z):	296	(M+).	Anal.	
Calcd.	 for	 C16H9N2O2Cl.	 C,	 64.86;	 H,	 3.04;	 N,	 9.45.	 Found:	 C,	
63.94;	H,	3.01;	N,	9.57%.	 

8‐bromo‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	 (5b):	
FT‐IR	(KBr,	,	cm‐1):	1741.	1H	NMR	(300	MHz,	DMSO‐d6):	7.38	
(d,	1H,	J	=	8.1	Hz,	C6‐H),	7.49‐7.54	(m,	2H,	C7‐H	&	Ph‐H),	7.59	(t,	
2H,	J	=	7.8	Hz,	Ph‐H),	7.81	(d,	2H,	J	=	8.4	Hz,	Ph‐H),	8.35	(d,	1H,	J	
=	2.9	Hz,	C9‐H),	8.71(s,	1H,	C3‐H).	13C	NMR	(75	MHz,	DMSO‐d6):	
106.9,	 115.1,	 119.0,	 123.8,	 127.3,	 129.5,	 129.8,	 131.3,	 132.4,	



226	 Lokhande	et	al.	/	European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	
	
135.5,	141.2,	148.1,	151.6,	159.8.	MS	(EI,	m/z):	340	(M+).	Anal.	
Calcd.	 for	 C16H9N2O2Br.	 C,	 56.47;	 H,	 2.64;	 N,	 8.23.	 Found:	 C,	
56.31;	H,	2.71;	N,	8.09%.	 

6‐chloro‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	 (5c):	
FT‐IR	(KBr,	,	cm‐1):	1740.	1H	NMR	(300	MHz,	DMSO‐d6):	7.21	
(t,	1H,	J	=	8.1	Hz,	C8‐H),	7.38‐7.43	(m,	2H,	C7‐H	&	Ph‐H),	7.60	(t,	
2H,	J	=	8.1	Hz,	Ph‐H),	7.84	(d,	2H,	J	=	8.4	Hz,	Ph‐H),	8.15	(dd,	1H,	
J1=8.1	Hz,	J2=	2.4	Hz,	C9‐H),	8.66	(s,	1H,	C3‐H).	13C	NMR	(75	MHz,	
DMSO‐d6):	 105.1,	 119.0,	 121.4,	 128.2,	 128.8,	 129.1,	 130.4,	
131.1,	 132.0,	 132.8,	 141.4,	 149.2,	 152.3,	 157.8.	MS	 (EI,	 m/z):	
296	(M+).	Anal.	Calcd.	for	C16H9N2O2Cl.	C,	64.86;	H,	3.04;	N,	9.45.	
Found:	C,	66.09;	H,	2.98;	N,	9.59%.	 

6,8‐Dichloro‐2‐	 phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	
(5d):	FT‐IR	(KBr,	,	cm‐1):	1747.	1H	NMR	(300	MHz,	DMSO‐d6):	
7.49	 (t,	1H,	 J	 =	7.5	Hz,	Ph‐H),	7.56‐7.61	(m,	3H,	C7‐H	&	Ph‐H),	
7.84	(d,	2H,	J	=	7.8	Hz,	Ph‐H),	8.10	(d,	1H,	J	=	2.4	Hz,	C9‐H),	8.72	
(s,	1H,	C3‐H).	13C	NMR	(75	MHz,	DMSO‐d6):	110.2,	118.1,	121.8,	
128.3,	 131.2,	 132.0,	 132.5,	 132.9,	 133.2,	 134.8,	 141.2,	 147.3,	
153.0,	 159.9.	 MS	 (EI,	 m/z):	 330	 (M+).	 Anal.	 Calcd.	 for	
C16H8N2O2Cl2.	C,	58.18;	H,	2.42;	N,	8.48.	Found:	C,	58.34;	H,	2.61;	
N,	8.11%.		

6,8‐Dibromo‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	
(5e):	FT‐IR	(KBr,	,	cm‐1):	1766.	1H	NMR	(300	MHz,	DMSO‐d6):	
7.49	(t,	1H,	J	=	7.5	Hz,	Ph‐H),	7.58	(t,	2H,	J	=	7.5	Hz,	Ph‐H),	7.83	
(d,	2H,	J	=	7.8	Hz,	Ph‐H),	7.88	(d,	1H,	J	=	2.1	Hz,	C7‐H),	8.29	(d,	
1H,	 J	 =	 2.1	 Hz,	 C9‐H),	 8.71	 (s,	 1H,	 C3‐H).	 13C	 NMR	 (75	 MHz,	
DMSO‐d6):	 107.8,	 116.1,	 121.4,	 124.6,	 127.8,	 131.0,	 132.2,	
132.8,	 134.3,	 137.4,	 139.9,	 149.6,	 152.9,	 161.2.	MS	 (EI,	 m/z):	
418	 (M+).	 Anal.	 Calcd.	 for	 C16H8N2O2Br2.	 C,	 45.93;	 H,	 1.91;	 N,	
6.69.	Found:	C,	46.12;	H,	1.83;	N,	6.78%.	 

6‐Bromo‐8‐chloro‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐
one	(5f):	FT‐IR	(KBr,	,	cm‐1):	1759.	1H	NMR	(300	MHz,	DMSO‐
d6):	7.49	(t,	1H,	J	=	7.5	Hz,	Ph‐H),	7.59	(t,	2H,	J	=	7.5	Hz,	Ph‐H),	
7.75	(d,	1H,	J	=	2.4	Hz,	C7‐H),	7.85	(d,	2H,	J	=	7.5	Hz,	Ph‐H),	8.15	
(d,	 1H,	 J	 =	 2.4,	 C9‐H),	 8.72	 (s,	 1H,	 C3‐H	 ).	 13C	 NMR	 (75	 MHz,	
DMSO‐d6):	 109.2,	 119.4,	 121.5,	 127.9,	 129.1,	 130.5,	 130.7,	
131.9,	 132.6,	 135.8,	 142.8,	 149.6,	 151.0,	 157.5.	MS	 (EI,	 m/z):	
374	 (M+).	 Anal.	 Calcd.	 for	 C16H8N2O2BrCl.	 C,	 51.33;	H,	 2.13;	N,	
7.48.	Found:	C,	51.64;	H,	2.34;	N,	7.31%.	 

6‐Bromo‐8‐methyl‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐
one	(5g):	FT‐IR	(KBr,	,	cm‐1):	1741.	1H	NMR	(300	MHz,	DMSO‐
d6):	2.44	(s,	3H,	CH3),	7.46	(t,	1H,	 J	=	7.2	Hz,	Ph‐H),	7.54‐	7.59	
(m,	3H,	C7‐H	&	Ph‐H),	7.84	(d,	2H,	J	=	7.5	Hz,	Ph‐H),	7.95	(d,	1H,	
J	=	1.2	Hz,	C9‐H),	8.69	(s,	1H,	C3‐H).	 13C	NMR	(75	MHz,	DMSO‐
d6):	25.1,	110.9,	117.4,	122.1,	127.9,	130.3,	131.2,	131.7,	132.0,	
134.7,	139.9,	140.8,	148.4,	150.4,	157.1.	MS	(EI,	m/z):	354	(M+).	
Anal.	Calcd.	for	C17H11N2O2Br.	C,	57.62;	H,	3.10;	N,	7.90.	Found:	
C,	57.41;	H,	2.93;	N,	7.61%.	 
	
2.2.6.	General	procedure	for	the	preparation	of	substituted	
of	2‐arylpyrazolo	[4,	3‐c]	coumarin	derivatives	(6a‐c)	
	

To	 a	 solution	 of	 3‐(2‐hydroxyaryl)‐1‐phenyl‐1H‐pyrazole‐
4‐carbaldehydes	 (3a‐c)	 (1	 mmol)	 or	 3‐(2‐(allyloxyaryl)‐1‐
phenyl‐1H‐pyrazole‐4‐carbaldehydes	(4a‐c)	(1	mmol)	in	DMSO	
(20	mL),	iodine	(1.2	equivalent)	and	4‐5	drops	of	concentrated	
H2SO4	was	added.	Then	the	reaction	mixture	was	heated	at	120	
oC.	After	 the	completion	of	 the	 reaction	(checked	by	TLC),	 the	
contents	were	cooled	to	room	temperature	and	poured	into	ice‐
cooled	water.	The	separated	solid	was	filtered	and	washed	with	
cooled	dilute	sodium	thiosulphate	solution.	Finally	the	obtained	
product	was	crystallized	from	DMF	to	give	product	6a‐c.	 

8‐Chloro‐6‐iodo‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	
(6a):	FT‐IR	(KBr,	,	cm‐1):	1745.	1H	NMR	(300	MHz,	DMSO‐d6):	
7.48	(t,	1H,	J	=	7.5	Hz,	Ph‐H),	7.57	(t,	2H,	J	=	7.5	Hz,	Ph‐H),	7.83	
(d,	2H,	J	=	8.4	Hz,	Ph‐H),	7.94	(d,	1H,	J	=	2.4	Hz,	C7‐H),	8.16	(d,	
1H,	 J	 =	 2.4	 Hz,	 C9‐H),	 8.71	 (s,	 1H,	 C3‐H).	 13C	 NMR	 (75	 MHz,	
DMSO‐d6):	87.3,	108.8,	115.6,	119.9,	121.7,	128.5,	129.3,	129.7,	
131.3,	138.5,	138.8,	147.5,	150.9,	155.7.	MS	(EI,	m/z):	422	(M+).	

Anal.	Calcd.	for	C16H8N2O2ClI.	C,	45.49;	H,	1.89;	N,	6.63.	Found:	
C,	45.61;	H,	2.01;	N,	6.31%. 

8‐Bromo‐6‐iodo‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	
(6b):	FT‐IR	(KBr,	,	cm‐1):	1743.	1H	NMR	(300	MHz,	DMSO‐d6):	
7.47	(t,	1H,	J	=	7.8	Hz,	Ph‐H),	7.57	(t,	2H,	J	=	7.8	Hz,	Ph‐H	),	7.83	
(d,	2H,	J	=	7.8	Hz,	Ph‐H),	8.08	(d,	1H,	J	=	2.4	Hz,	C7‐H),	8.31	(d,	
1H,	 J	 =	 2.1	 Hz,	 C9‐H),	 8.70	 (s,	 1H,	 C3‐H).	 13C	 NMR	 (75	 MHz,	
DMSO‐d6):	87.9,	108.2,	115.4,	115.6,	119.3,	124.2,	129.7,	130.1,	
130.9,	138.1,	141.2,	148.1,	151.8,	156.3.	MS	(EI,	m/z):	466	(M+).	
Anal.	Calcd.	for	C16H8N2O2BrI.	C,	41.20;	H,	1.71;	N,	6.00.	Found:	
C,	41.51;	H,	1.87;	N,	6.24%. 

6‐Chloro‐8‐iodo‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	
(6c):	FT‐IR	(KBr,	,	cm‐1):	1749.	1H	NMR	(300	MHz,	DMSO‐d6):	
7.48‐7.51	(m,	1H,	Ph‐H),	7.58	(t,	2H,	J	=	7.2	Hz,	Ph‐H),	7.87	(d,	
1H,	J	=	1.8	Hz,	C7‐H),	7.92	(d,	2H,	J	=	7.2	Hz,	Ph‐H),	8.42	(d,	1H,	J	
=	2.1	Hz,	C9‐H),	9.01	(s,	1H,	C3‐H	).	13C	NMR	(75	MHz,	DMSO‐d6):	
87.5,	 109.5,	 115.8,	 120.8,	 121.0,	 128.3,	 131.4,	 131.6,	 131.8,	
138.6,	138.9,	148.0,	148.9,	156.0.	MS	(EI,	m/z):	422	(M+).	Anal.	
Calcd.	 for	 C16H8N2O2ClI.	 C,	 45.49;	 H,	 1.89;	 N,	 6.63.	 Found:	 C,	
45.41;	H,	1.81;	N,	6.59%. 
	
3.	Results	and	discussion		

	
The	overall	 synthetic	 route	 utilized	 for	 the	preparation	 of	

the	 target	 pyrazolocoumarin	 is	 depicted	 in	 Scheme	 1	 and	
Scheme	2.	Our	approach	to	the	synthesis	of	the	target	molecule,	
started	 from	 the	 condensation	 of	 halo	 substituted	 o‐
hydroxyacetophenones,	 1a‐g,	 with	 phenyl	 hydrazine	 to	
efficiently	 provide	 the	 hydrazones,	 2a‐g.	 These	 derivatives	
were	 purified	 and	 transformed	 into	 the	 corresponding	 3‐(2‐
hydroxyaryl)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehydes,	 3a‐g,	 by	
using	 the	 Vilsmeier	 reagent	 (according	 to	method	 of	 Rathelot	
et.	 al.	 [34]).	 The	 3‐(2‐(allyloxyaryl)‐1‐phenyl‐1H‐pyrazole‐4‐
carbaldehydes,	 4a‐g,	 were	 readily	 prepared	 from	 3a‐g	 using	
the	ally	bromide	in	DMSO	(Scheme	1).	These	key	intermediate	
substituted	 pyrazole‐4‐carbaldehydes	 (3a‐g	 &	 4a‐g)	 were	
required	for	the	synthesis	of	2‐arylpyrazolo[4,3‐c]coumarins.	
	

 
	

Scheme	1	
		
	

	
	

Scheme	2	
	



Lokhande	et	al.	/	European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	 227	
 

 
 

	 	

	
	

 R1 R2  R1 R2 R1 R2 R1 R2

3a H Cl  4a H Cl  5a H Cl  6a I Cl 
3b H Br  4b H Br  5b H Br  6b I Br 
3c Cl H  4c Cl H  5c Cl H  6c Cl I 
3d Cl Cl  4d Cl Cl  5d Cl Cl     
3e Br Br  4e Br Br  5e Br Br     
3f Br Cl  4f Br Cl  5f Br Cl     
3g Br Me  4g Br Me  5g Br Me     

	
(a)	I2	(10	mol	%)	/DMSO,	conc.	H2SO4,	120	oC,	5‐7	h.	
(b)	I2	(1.2	equiv.)/DMSO,	conc.	H2SO4,	120	oC,	3‐4	h.	

	
Scheme	3

	
	
Initially,	we	 attempted	 the	 oxidative	 cyclization	 of	 3‐(3,5‐

dichloro‐2‐hydroxyphenyl)‐1‐phenyl‐1H‐pyrazole‐4‐carbalde‐
hyde,	 3d,	 using	 iodine	 (5%)	 in	 dimethylsulfoxide	 in	 the	
presence	of	H2SO4	at	60	oC	as	per	our	known	procedures	for	the	
flavone	 synthesis	 [23].	 The	 product	 was	 not	 appearing	 even	
after	30	h.	Showing	that	the	formyl	group	of	the	pyrazole	is	not	
reactive.	 Actually	 the	 reaction	 rate	 depended	 on	 the	 catalyst	
amount	 and	 temperature	 (Scheme	 2,	 Table	 1).	 The	 best	
condition	was	 obtained,	 using	 of	 10%	 iodine	 in	 DMSO	 in	 the	
presence	 of	 catalytic	 amount	 of	 H2SO4	 at	 120	 oC,	 and	 the	
reaction	went	to	completion	within	5	h	and	the	corresponding	
product	5d	was	obtained	 in	92%	yield	 (Table	1).	 Encouraged	
based	 on	 these	 results,	 various	 4‐formylpyrazoles	 were	
converted	 to	 the	 corresponding	 coumarins	 in	 87‐94	 %	 yield	
(Scheme	 3,	 Table	 2).	 The	 reaction	 probably	 proceeds	 via	
formation	of	hemiacetals	by	the	reaction	of	4‐formyl	group	and	
phenol,	and	the	oxidation	of	hemiacetal	to	lactone	by	molecular	
iodine	in	dimethylsulfoxide.	
	
Table	1.	Effect	of	the	catalyst	iodine	and	temperature	on	the	synthesis	of	6,8‐
dichloro‐2‐phenylchromeno[4,3‐c]pyrazol‐4(2H)‐one	(4d).	

Yield	(%)Time	(h) Temp	(oC)Mol	(%) Entry 
NR30 RT 5 1 
NR30 RT 10 2 
NR30 RT 15 3 
NR30 RT 20 4 
NR30 60 5 5 
NR30 60 10 6 
NR30 60 15 7 
2026 60 20 8 
6020 120 5 9 
925 120 10 10 

	RT:	Room	temperature.	
	NR:		No	Reaction.	

	
According	 to	 our	 research	 in	 deallylation	 of	 2'‐

allyloxychalcones	[30],	we	attempted	 to	apply	 this	 reagent	 for	
3‐(2‐(allyloxyaryl)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehydes,	4a‐
g.	 In	 this	 case	 also	 4a‐g	 interestingly	 easily	 under	 went	 to	

deallylation	as	well	as	cyclization,	and	gave	the	corresponding	
pyrazolocoumarin	(Scheme	3).	
	
Table	2.	Physico‐chemical	data	of	2‐arylpyrazolo[4,3‐c]coumarins.	
Entry R1 R2 M.p.	(	oC) Yield	(%)	 Time (h)
5a H Cl 189‐190 89	a,	91b	 7
5b H Br 196‐197 91	a,	89b	 6.5
5c Cl H 183‐184 93	a,	88b	 7
5d Cl Cl 233‐234 92	a,	88b	 5
5e Br Br 248‐249 88	a,	89b	 5
5f Br Cl 258‐259 92	a,	87b	 5.5
5g Br Me 254‐255 94	a,	88b	 5
6a I Cl 203‐204 87	a,	87b	 3.5
6b I Br 259‐260 89	a,	87b 3
6c Cl I 208‐209 91	a,	86b 4
a	Yield	of	cyclization	of	3a‐g.	
b	Yield	of	cyclization	of	4a‐g.	
	

On	the	other	hand	the	excess	in	mol%	of	iodine	(1.2	equiv.)	
on	 the	mono	 substituted	 compounds	 of	3a‐g	 &	4a‐g	 leads	 to	
iodination	 at	 the	 phenol	 ring	 (Entry	 6a,	 6b	 and	 6c,	 Table	 2,	
Scheme	3).	If	the	para	position	in	the	phenol	moiety	is	blocked	
the	 iodination	 takes	place	at	 the	ortho	position	 (Entry	6a,	6b,	
Table	 2),	while	 if	 the	 ortho	 position	 is	 blocked	 the	 iodination	
takes	 place	 at	 the	 para	 position	 (Entry	 6c,	 Table	 2).	 The	
structure	of	the	synthesized	compounds	was	confirmed	on	the	
basis	of	spectroscopic	methods.	Lower	amount	of	iodine	(30%,	
50%)	 gave	 the	 mixture	 of	 iodosubstituted	 and	 unsubstituted	
products.	While	 in	other	prazoles	were	already	 substituted	 at	
both	 positions	 in	 the	 phenol	 moiety	 hence	 no	 iodination	
observed.	
	
4.	Conclusion	
	

In	 summary,	we	 have	 developed	 a	 simple	 and	 convenient	
method	 for	 the	 synthesis	 of	 2‐arylpyrazolo[4,3‐c]coumarins	
using	 I2/DMSO	 as	 an	 efficient	 catalytic	 system.	 The	 present	
methodology	 is	 clean;	 eliminates	 the	 toxic	 metal	 oxidant,	



228	 Lokhande	et	al.	/	European	Journal	of	Chemistry	2	(2)	(2011)	223‐228	
	
shorter	 reaction	 times,	 high	 yields,	 easy	 of	workup	 and	more	
applicable	for	the	medicinal	as	well	as	pharmaceutical	chemist.	
	
Acknowledgements	
	

SGK	is	thankful	to	Dr.	D.S.	Kothari	Post	Doctoral	Fellowship	
No.	 [F.4‐2/2006(BSR)/13‐301/2008	 (BSR)],	 UGC‐New	 Delhi	
for	 financial	 support.	 Authors	 are	 also	 thankful	 to	 Garware	
Research	Centre,	Pune	for	spectral	and	elemental	analysis.	
	
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