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European	Journal	of	Chemistry	2	(1)	(2011)	100‐103	

	
European	Journal	of	Chemistry	

ISSN	2153‐2249	(Print)	/	ISSN	2153‐2257	(Online)		2011	EURJCHEM	
DOI:10.5155/eurjchem.2.1.100‐103.175	

	
	

	

	

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

	 	 	

One‐pot	multicomponent	route	to	propargylamines	using	ferric	
hydrogensulfate	

Hossein	Eshghi*,	Gholam	Hossein	Zohuri	and	Saman	Damavandi	

Department	of	Chemistry,	Ferdowsi	University	of	Mashhad,	Mashhad,	IR‐91775‐1436,	Iran	

*Corresponding	author	at:	Department	of	Chemistry,	Ferdowsi	University	of	Mashhad,	Mashhad,	IR‐91775‐1436,	Iran.	Tel.:	+98.511.8797660;	fax:	+98.511.8796416.	
E‐mail	address:	heshghi@ferdowsi.um.ac.ir	(H.	Eshghi).	

	
	

	 	

	 	 	
ARTICLE	INFORMATION	 	 ABSTRACT
Received:	19	June	2010	
Received	in	revised	form:	24	October	2010	
Accepted:	15	December	2010	
Online:	31	March	2011	

KEYWORDS	

	 The	 one‐pot	 three‐component	 coupling	 reaction	 of	 phenylacetylene,	 aldehyde	 and	 amine
derivatives	 in	 the	 presence	 of	 ferric	 hydrogensulfate,	 [(Fe(HSO4)3],	 as	 an	 efficient
heterogeneous	 catalyst	 is	 reported.	 The	 catalyst	 displayed	 high	 activity	 and	 afforded	 the
corresponding	 propargylamines	 in	 good	 to	 excellent	 yields.	 This	method	 provides	 the	wide
range	 of	 substrate	 applicability.	 Heterogeneous	 nature	 of	 the	 catalyst	 made	 it	 reusable	 for
further	chemical	reactions.	

Ferric	hydrogensulfate	
Propargylamine	
Heterogeneous	catalyst	
Multicomponent	reaction	
One‐pot	synthesis	
Propargylic	amines	

	
1.	Introduction	
	

Addition	 reaction	 of	 carbanions	 to	 the	 carbonyl	 group	 of	
aldehydes	 and	 ketones	 [1‐4],	 and	 addition	 of	 organometallic	
reagents	 to	 the	 C=N	bonds	 of	 imines	 or	 imine	 derivatives	 are	
important	 reactions	 in	organic	 synthesis	 [5‐9].	Another	useful	
method	 for	carbon‐carbon	bond	 formation	 is	usage	of	alkynes	
as	 a	 carbon	 nucleophile	 source	 [10,11].	 The	 resulting	 alkynyl	
amine	derivatives	can	undergo	further	transformations	and	are	
versatile	 synthetic	 tools	 [12‐14].	 However,	 the	 reactive	
alkynilides	are	usually	prepared	from	terminal	alkyne	by	using	
highly	reactive	organometallic	reagents	such	as	n‐butyllithium	
(BuLi)	 [15,16],	 EtMgBr	 [17,18],	 or	 lithium	 diisopropylamide	
(LDA)	 [19,20]	 in	 a	 separate	 step,	 and	many	metal	 alkynilides	
are	not	easy	to	handle	because	the	reaction	must	be	carried	out	
under	 anhydrous	 solvent,	 inert	 atmosphere,	 and	 low	
temperature	 conditions.	 Therefore,	 the	 development	 of	 a	
method	 for	 the	 direct	 alkynylation	 of	 imines,	 which	 doesn’t	
need	to	use	a	stoichiometric	amount	of	highly	reactive	catalyst	
and	can	be	carried	out	under	mild	conditions,	would	be	highly	
desirable.	

Optically	 active	 propargyl	 amines	 are	 important	 synthetic	
intermediates	for	the	synthesis	of	various	nitrogen	compounds	
such	 as	 β‐lactams,	 oxotremorine	 analogues,	 confirmationally	
restricted	 peptides	 and	 they	 are	 components	 of	 bioactive	
compounds	or	natural	products	[21‐23].	

Recently	 great	 efforts	 have	 been	 devoted	 to	 develop	 the	
methodology	 for	generating	propargylamines	and	some	direct	
alkynylations	 of	 carbonyl	 compounds	 with	 terminal	 alkynes	
have	been	reported	[24‐29].	Several	transition	metal	salts	such	
as	gold,	copper,	silver,	and	Cu/Ru	system	have	been	employed	
in	 water	 as	 well	 as	 in	 ionic	 liquids	 [25‐27].	 Recently,	 solid‐
supported	 metal	 catalysts	 such	 as	 CuI/Al2O3,	 AuCl4/LDH,	
Cu/HAP	 and	 alternative	 energy	 sources	 like	 microwave	 and	

ultrasound	 have	 been	 utilized	 in	 the	 presence	 of	 CuI	 to	
accomplish	this	reaction	via	C‐H	activation	[26,29].	

Herein,	 propargylamines	 were	 synthesized	 successfully	
using	 ferric	 hydrogensulfate	 as	 an	 efficient	 heterogeneous	
catalyst.	 Various	 amines	 and	 aldehydes	 were	 employed	 to	
generalize	 this	 study.	We	reported	 that	 ferric	hydrogensulfate	
is	a	highly	effective	catalyst	 for	 the	 three‐component	coupling	
of	 aldehyde,	 alkyne,	 and	 amine	 to	 generate	 propargylamines	
(Figure	1).	

	

	
	

Figure	1.	Ferric	hydrogensulfate‐catalyzed	three‐component	synthesis	of	
propargylamines.	
	
2.	Experimental	
	
2.1.	Chemicals	and	reagents	
	

Chemicals	 were	 either	 prepared	 in	 our	 laboratories	 or	
purchased	from	Merck,	Fluka,	and	Aldrich	Chemical	Companies.	
All	 yields	 refer	 to	 isolated	 products.	 The	 reactions	 were	
monitored	by	thin‐layer	chromatography	(TLC)	carried	out	on	
silica	plates.	The	products	were	characterized	by	comparison	of	
their	 physical	 data	 with	 those	 of	 known	 samples	 or	 by	 their	
spectral	data.	 IR	spectra	were	recorded	on	a	Shimadzu‐IR	470	
spectrophotometer.	1H	NMR	spectra	was	recorded	on	a	Bruker‐
100	 MHz	 spectrometer	 in	 CDCl3	 as	 the	 solvent	 and	 TMS	 as	
internal	standard.	All	of	the	products	are	known	products	and	
all	 of	 the	 isolated	 products	 gave	 satisfactory	 IR	 and	 NMR	



Eshghi	et	al.	/	European	Journal	of	Chemistry	2	(1)	(2011)	100‐103	 101	
 

 
 

spectra.	 Ferric	 hydrogensulfate	 was	 prepared	 according	 to	
previously	reported	procedure	[33,34].	
	
2.2.	General	procedure	for	preparation	of	propargylamines	
	

Amines	 (1.1	 equiv.),	 aldehydes	 (1.0	 equiv.),	 phenyl	
acetylene	 (1.0	 equiv),	 and	 ferric	 hydrogensulfate	 (0.1	 equiv.)	
were	 successively	 added	 to	 CH3CN	 (10	 mL).	 The	 progress	 of	
reaction	 was	 monitored	 by	 TLC.	 After	 the	 reaction	 was	
completed,	 chloroform	 (5	mL)	was	 added	 and	 the	 slurry	was	
stirred,	 and	 then	 filtered	 using	 a	 sintered‐glass	 funnel.	 The	
residue	was	washed	to	ensure	removal	of	the	product	from	the	
surface	 of	 the	 catalyst.	 The	 combined	 organic	 phases	 were	
dried	 over	 Na2SO4	 and	 concentrated	 to	 give	 the	 almost	 pure	
corresponding	propargylamine.	The	final	product	was	purified	
by	short	column	chromatography	(eluent;	hexane:	ethyl	acetate	
(4:1)).	All	of	the	products	are	known	compounds	and	have	been	
reported	already.	

N‐(1,3‐Diphenyl‐2‐propynyl)morpholine	 (entry	 1):	 1H	 NMR	
(100	MHz,	 CDCl3):	 δ	 =	 7.00‐7.60	 (m,	 10H),	 4.70	 (s,	 1H),	 3.50‐
3.60	(m,	4H),	2.75‐2.90	(m,	4H).	

N‐[1‐(4‐Chlorophenyl)‐3‐phenyl‐2‐propynyl]morpholine	
(entry	 2):	 1H	 NMR	 (100	 MHz,	 CDCl3):	 δ	 =	 7.10‐7.60	 (m,	 9H),	
4.90	(s,	1H),	3.60‐3.70	(m,	4H),	2.35‐2.45	(m,	4H).	

N‐[1‐(4‐Methylphenyl)‐3‐phenyl‐2‐propynyl]morpholine	
(entry	 3):	 1H	 NMR	 (100	 MHz,	 CDCl3):	 δ	 =	 7.00‐7.30	 (m,	 9H),	
4.95	(s,	1H),	3.40‐3.55	(m,	4H),	2.25‐2.45	(m,	4H),	2.30	(s,	3H).		

N‐[1‐(4‐Methoxyphenyl)‐3‐phenyl‐2‐propynyl]morpholine	
(entry	 4):	 1H	 NMR	 (100	 MHz,	 CDCl3):	 δ	 =	 7.10‐7.40	 (m,	 9H),	
4.75	(s,	1H),	3.95	(s,	3H),	3.40‐3.60	(m,	4H),	2.40‐2.55	(m,	4H).	

N‐[1‐(Furfuryl)‐3‐phenyl‐2‐propynyl]morpholine	 (entry	 5):	
1H	NMR	(100	MHz,	CDCl3):	δ	=	6.70‐7.15	(m,	8H),	4.65	(s,	1H),	
3.55‐370	(m,	4H),	2.25‐2.35	(m,	4H).	

N‐[1‐(3‐Phenylprop‐2‐ynyl)]morpholine	 (entry	 6):	 1H	 NMR	
(100	 MHz,	 CDCl3):	 δ	 =	 7.00‐7.30	 (m,	 5H),	 3.45–3.60	 (m,	 4H),	
3.25	(s,	2H),	2.65–2.75	(m,	4H).	

N‐(1,3‐Diphenyl‐2‐propynyl)pyrolidine	 (entry	 7):	 1H	 NMR	
(100	MHz,	 CDCl3):	 δ	 =	 6.80‐7.60	 (m,	 10H),	 4.90	 (s,	 1H),	 2.95‐
3.30	(m,	4H),	0.90	(t,	4H,	J=8	Hz).	

N‐(1‐(4‐Chlorophenyl)‐3‐phenyl‐2‐propynyl)pyrolidine	
(entry	 8):	 1H	 NMR	 (100	 MHz,	 CDCl3):	 δ	 =	 7.10‐7.60	 (m,	 9H),	
4.80	(s,	1H),	2.65	(t,	4H,	J=8	Hz),	1.10	(t,	4H,	J=8	Hz).	

N‐[1‐(4‐Methylphenyl)‐3‐phenyl‐2‐propynyl]pyrolidine	
(entry	 9):	 1H	 NMR	 (100	 MHz,	 CDCl3):	 δ	 =	 7.00‐7.50	 (m,	 9H),	
4.95	(s,	1H),	2.35‐2.60	(m,	4H),	2.55	(s,	3H),	1.20	(t,	4H,	J=8	Hz).	

N‐[1‐(4‐Methoxyphenyl)‐3‐phenyl‐2‐propynyl]pyrolidine	
(entry	10):	 1H	NMR	 (100	MHz,	 CDCl3):	 δ	 =	6.90‐7.60	 (m,	 9H),	
5.05	(s,	1H),	3.25	(s,	3H),	2.85–3.05	(m,	4H),	0.90‐1.10	(m,	4H).	

N‐[1‐(Furfuryl)‐3‐phenyl‐2‐propynyl]pyrolidine	 (entry	 11):	
1H	NMR	(100	MHz,	CDCl3):	δ	=	6.95‐7.25	(m,	8H),	4.80	(s,	1H),	
2.50‐2.65	(m,	4H),	1.25	(t,	4H,	J=8	Hz).	

N‐(1,3‐Diphenyl‐2‐propynyl)piperidine	 (entry	 12):	 1H	 NMR	
(100	MHz,	 CDCl3):	 δ	 =	 7.00‐7.55	 (m,	 10H),	 4.90	 (s,	 1H),	 2.60‐
2.80	(m,	4H),	1.75	(m,	6H).		

N‐[1‐(4‐Methylphenyl)‐3‐phenyl‐2‐propynyl]piperidine	
(entry	13):	 1H	NMR	 (100	MHz,	 CDCl3):	 δ	 =	7.15‐7.70	 (m,	 9H),	
4.80	(s,	1H),	2.45‐2.55	(m,	4H),	2.20	(s,	3H),	1.40‐1.68	(m,	6H).		

N‐[1‐(4‐Methoxyphenyl)‐3‐phenyl‐2‐propynyl]piperidine	
(entry	14):	 1H	NMR	 (100	MHz,	 CDCl3):	 δ	 =	7.00‐7.65	 (m,	 9H),	
4.85	(s,	1H),	3.81	(s,	3H),	2.50‐2.70	(m,	4H),	1.45‐1.65	(m,	6H).		

N‐[1‐(4‐Chlorophenyl)‐3‐phenyl‐2‐propynyl]piperidine	
(entry	15):	 1H	NMR	 (100	MHz,	 CDCl3):	 δ	 =	7.20‐7.62	 (m,	 9H),	
4.80	(s,	3H),	2.45‐2.65	(m,	4H),	1.50‐1.75	(m,	6H).		

N‐[1‐(Furfuryl)‐3‐phenyl‐2‐propynyl]piperidine	 (entry	 16):	
1H	NMR	(100	MHz,	CDCl3):	δ	=	7.35‐7.61	(m,	8H),	4.76	(s,	3H),	
2.60‐2.75	(m,	4H),	1.45‐1.75	(m,	6H).		

N‐[1‐(3‐Phenylprop‐2‐ynyl)]piperidine	 (entry	 17):	 1H	 NMR	
(100	MHz,	CDCl3):	δ	=	7.20‐7.55	(m,	5H),	3.50	(s,	2H),	2.40‐2.55	
(m,	4H),	1.35‐1.50	(m,	6H).		

N‐Cyclohexyl‐3‐phenylprop‐2‐ynylamine	(entry	18):	1H	NMR	
(100	MHz,	CDCl3):	δ	=	7.25‐7.65	(m,	5H),	4.55	(s,	1H),	3.75	(s,	
2H),	2.45	(m,	1H),	1.80‐1.95	(m,	4H),	1.45‐1.60	(m,	6H).	

1‐(1‐Cyclopentyl‐3‐phenylprop‐2‐ynyl)piperidine	 (entry	
20):	1H	NMR	(100	MHz,	CDCl3):	δ	=	7.25‐7.55	(m,	5H),	3.75	(d,	
1H,	 J=5	Hz),	2.50	 (m,	4H),	1.8‐1.95	(m,	5H),	 	1.4‐1.65	(m,	5H),	
0.9‐1.15	(m,	5H).	

1‐(1‐Cyclohexyl‐3‐phenylprop‐2‐ynyl)pyrrolidine	 (entry	
22):	1H	NMR	(100	MHz,	CDCl3):	δ	=	7.00‐7.40	(m,	5H),	3.85	(d,	
1H,	J=8	Hz),	2.50	(t,	4H,	J=8	Hz),	1.05‐1.80	(m,	15H).	
	
3.	Results	and	discussion		
	

Using	 morpholine	 as	 the	 amine,	 phenyl	 acetylene	 as	 the	
alkyne	 and	 benzaldehyde	 as	 the	 aldehyde	 component	 in	 a	
stoichiometric	 ratio	 of	 1.1:1:1	 and	 0.1	 equiv.	 ferric	
hydrogensulfate	 (based	 on	 the	 alkyne	 component),	 we	
designed	 a	 reaction	 as	 a	model	 in	 order	 to	 find	 the	 optimum	
reaction	solvent	and	the	results	are	shown	in	Table	1.		
	
Table	 1.	 Influence	 of	 solvent	 on	 Fe‐catalyzed	 reaction	 of	 benzaldehyde,	
morpholine	and	phenylacetylene	and	reusability	study.	
Entry Solvent Yield	(%)a,b
1 Tetrahydrofuran 35	
2 Toluene 52	
3 Ethanol 60	
4 Dichloromethane 75	
5 Methanol 80	
6 Acetonitrile 90	
7c Acetonitrile 90	
8d Acetonitrile 88	
9e Acetonitrile 87	
10f Acetonitrile 84	
a	Reaction	conditions:	1.0	equiv.	of	benzaldehyde,	1.0	equiv.	of	morpholine,	
1.1	 equiv	 of	 phenylacetylene,	 10	 mol%	 ferric	 hydrogenesulfate	 and	 reflux	
condition;	 b	 Isolated	 yields;	 c‐f	 Reusability	 of	 the	 recovered	 catalyst	 in	 new	
runs.	

	
Among	the	various	solvent	 investigated,	CH3CN	was	 found	

to	 be	 the	 best	 choice	 (Table	 1,	 entry	 6),	 while	 toluene	 and	
ethanol	 afforded	 lower	 yields	 (Table	 1,	 Entries	 2	 and	 3).	
Moderate	 yields	 were	 obtained	 when	 the	 reactions	 were	
carried	 out	 in	 CH3OH	 and	 CH2Cl2	 (Table	 1,	 Entries	 4	 and	 5).	
Poor	 results	 were	 observed	 when	 the	 reactions	 were	 carried	
out	 in	 THF	 (Table	 1,	 Entry	 1).	 This	 may	 be	 due	 to	 the	 high	
polarity	 associated	 with	 CH3CN,	 which	 may	 result	 in	 the	
stabilization	of	the	alkenyl‐Fe	intermediate.	

In	the	present	work	reusability	of	the	catalyst	was	studied	
in	 the	 reaction	 of	 benzaldehyde,	 morpholine,	 and	
phenylacetylene	 in	 the	presence	of	 the	 catalyst	 in	 acetonitrile	
as	 a	 solvent.	 After	 completion	 of	 each	 run,	 the	 catalyst	 was	
recovered	and	used	 for	 further	 reactions.	As	 it	 can	be	 seen	 in	
Table	1,	the	catalyst	could	be	reused	without	significant	loss	of	
its	catalytic	activity	until	at	least	4	times.	

Subsequently,	to	extend	the	study	of	this	three‐component	
coupling	 reaction,	 we	 used	 different	 derivatives	 of	 aldehydes	
and	 amines	 in	 reaction	 with	 phenylacetylene.	 Actually,	
phenylacetylene	 was	 used	 as	 a	 model	 substrate,	 and	 various	
amines	and	aldehydes	were	examined	(Table	2,	Entries	1‐18).	

The	results	 indicated	 that	heterocyclic	 secondary	aliphatic	
amines	 gave	 excellent	 yields	 of	 products	 at	 the	 reaction	
conditions,	 while	 the	 selected	 primary	 aliphatic	 amine,	
cyclohexylamine,	 generated	 the	 corresponding	 secondary	
propargylamines	in	moderate	yield	(Table	2,	Entry	18).	

Among	 the	 various	 amines	 used,	 piperidine	 showed	 the	
highest	 reactivity	 in	 terms	of	yields	and	 reaction	 times.	 It	 can	
be	 inferred	 that	 electronically	nature	 of	 substitutions	 affected	
the	 reaction	 to	 some	 extent.	 The	 aldehydes	 containing	 an	
electron‐withdrawing	 group	 afforded	 better	 yields	 (Table	 2,	
Entries	 2,8,15)	 than	 those	 with	 an	 electron‐donating	 group	
(Table	 2,	 Entries	 4,	 10	 and	 14).	 Heteroaromatic	 aldehyde,	
furfuraldehyde,	 reacted	 to	 obtain	 the	 corresponding	



102	 Eshghi	et	al.	/	European	Journal	of	Chemistry	2	(1)	(2011)	100‐103	
	
propargylamines	 in	 good	 to	 excellent	 yields	 (Table	 2,	 entries	
5,11,16).	

	
Table	 2.	 Results	 of	 propargylamine	 compounds	 preparation	 using	 ferric	
hydrogensulfate.	

Entry	 Aldehyde	 Amine	 Productb	 Yield	
(%)c	

Time	
(h)	

1	 CHO
	 N

H

O

	

N

O

Ph 	

87	 6	

2	 CHOCl
	 N

H

O

	

N

O

Ph
Cl 	

88	 5	

3	 CHOMe
	 N

H

O

	

N

O

Ph
Me 	

88	 9	

4	 CHOMeO
	 N

H

O

	

N

O

Ph
MeO 	

71	 8.5	

5	
O CHO 	 N

H

O

	

N

O

O
Ph 	

83	 4.5	

6	 C
H H

O

	 N
H

O

	 H

N

O

H
Ph
	

90	 4	

7	 CHO
	 N

H 	 Ph

N

	
78	 5	

8	 CHOCl
	 N

H 	 Ph

N

Cl 	
90	 6.5	

9	 CHOMe
	 N

H 	 Ph

N

Me 	
90	 8	

10	 CHOMeO
	 N

H 	 Ph

N

MeO 	
73	 9	

11	
O CHO 	 N

H 	 O
Ph

N

	
85	 6	

12	 CHO
	 N

H 	 Ph

N

	

94	 4	

13	 CHOMe
	 N

H 	 Ph

N

Me 	
90	 5.5	

14	 CHOMeO
	 N

H 	 Ph

N

MeO 	
84	 7	

15	 CHOCl
	 N

H 	 Ph

N

Cl 	

94	 7	

16	
O CHO 	 N

H 	
Ph

N

O 	

90	 4	

17	 C
H H

O

	 N
H 	 H

N

H
Ph
	

95	 4	

18	 C
H H

O

	 NH2 	 H

Ph
H

NH

	

55	 7	

19	
H

O

	 N
H 	

N

O

Ph 	

82	 7	

20	
O H

	
N
H 	

N

Ph 	

92	 5	

21	

O H

	
N
H 	

N

Ph 	

85	 5	

22	

O H

	
N
H 	

N

Ph 	

94	 5	

a	Reaction	conditions:	1.1:1:1	equiv.	of	amine,	phenlacetylene	and	aldehyde,	
1.0	equiv.	Fe(HSO4)3	and	reflux	condition.	b	The		products	were	identified	by	
1H	NMR	and	IR	spectra.	c	Isolated	yields.	
	

The	 scope	was	extended	by	using	a	variety	of	 structurally	
diverse	 aliphatic	 aldehydes	 (Table	 2,	 Entries	 19‐22).	 The	
results	 reveal	 that	 ferric	 hydrogensulfate	 can	 promote	 the	
condensation	 of	 aliphatic	 aldehydes,	 amines,	 and	 phenyl‐
acetylene	 and	 the	 corresponding	 propargylamines	 were	
obtained	in	high	yields.		

On	the	basis	of	several	literature	publications	[30‐32],	 it	 is	
believed	 that	 the	 coupling	 reaction	 mechanism	 proceeds	 by	
terminal	alkyne	C‐H	bond	activation	by	 ferric	hydrogensulfate	
catalyst	 (Figure	 2).	 The	 Fe‐alkenyl	 (acetylide)	 intermediate	
would	attack	on	iminium	ion,	which	is	prepared	in	situ	from	the	
aldehyde	 and	 secondary	 amine,	 to	 obtain	 the	 corresponding	
propargylamine	 and	 regenerated	 the	 catalyst	 for	 further	
reactions.	

	

 
	
	

Figure	2.	Synthetic	route	to	prepare	propargylamines.
	

In	order	to	show	the	merit	of	this	study,	we	compared	the	
obtained	 results	 with	 the	 results	 reported	 recently.	 For	 this	
purpose,	the	reactions	of	phenylacetylene,	piperidine	and	some	
aldehydes	were	chosen	as	model	reactions	and	comparison	was	
carried	 out	 on	 the	 basis	 of	 reaction	 conditions,	 reaction	 time,	
and	 percentage	 yields	 obtained	 (Table	 3).	 It	 is	 worth	
mentioning	that	this	method	is	faster	and	simpler	than	some	of	
the	existing	methods.	The	efficiency,	advantages	and	generality	
of	 the	 ferric	hydrogensulfate	can	be	elucidated	by	comparison	
of	 the	 results	 obtained	 in	 this	 study	 with	 those	 reported	
already.	

	
4.	Conclusion	

	
In	 conclusion,	 we	 have	 reported	 an	 efficient	 synthesis	 of	

propargylamines	 through	 three‐component	 coupling	 of	
aldehydes,	 amines	 and	 phenylacetylene	 via	 C‐H	 activation	 by	
ferric	 hydrogensulfate	 as	 a	 suitable	 heterogeneous	 catalyst.	
Recyclability	of	the	catalyst	without	significant	loss	of	catalytic	
activity,	 easy	 procedure	 and	 work‐up,	 broad	 substrate	
applicability,	high	yields	attained	in	almost	short	reaction	times	
can	 be	 mentioned	 as	 advantages	 of	 this	 method.	 Finally,	 this	
approach	 could	 make	 a	 valuable	 contribution	 to	 the	 existing	
processes	in	the	field	of	propargylamine	synthesis.	
	
Acknowledgement	

	
We	are	grateful	to	Ferdowsi	University	of	Mashhad	Research	

Council	for	their	financial	support	of	this	work.	
	

References	
	
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Eshghi	et	al.	/	European	Journal	of	Chemistry	2	(1)	(2011)	100‐103	 103	
 

 
 

	
Table	3.	Comparison	of	propargylamine	formation	by	Fe(HSO4)3	with	literature	reported	methods.	

Time	(h)/Yield	(%)	[Lit.]Reaction	conditionsCatalyst	Substrate	 Entry		
24/79	[24] 
25/35	[25] 
0.1/97	[26]	
9/90	[35]	
5/94	[36]	
24/94	[37]	
14/70	[38]	
5/78	[39] 
6/82	[41]	
5/92	[42]		
8/95	[43]	
4/94	a	

Solventless,	r.t. 
CH3CN,	60	oC 
Dioxane/ionic	liquid/US	irradiation	
CH3CN,	reflux 
CH3CN,	75–80	oC 
H2O,	N2,	40	oC 
100	°C,	water	
100	oC,	Ionic	liquid	
Toluene,	90	oC	
CH3CN,	reflux	
Toluene,	111oC 
CH3CN,	reflux

SiO2‐NH‐Cu,	2	mol%  
Cu	Zeolites,	20	mg  
CuCl,	10	mol%  
Zn	dust,	15	mol	%  
Au	nanoparticles,	10	mol%  
Gold(III)	salen,	0.05	mol%	
AgI,	3	mol%	
CuI,	10	mol%	
Nanocrystalline	CuO	
12‐tungstophosphoric	acid	30	mg	
NiCl2	5	mol% 
Fe(HSO4)3,	10	mol% 

Benzaldehyde 
 
 
 
 
 
 
 
	

1	
 

24/93	[24]	
0.1/99	[26]	
8/95	[35]	
7/70	[40]	
6/85	[41]	
4/98	[42]	 
9/87	[43]	
7/94	[a]	

Solventless,	r.t.
Dioxane/ionic	liquid/US	irradiation	
CH3CN,	reflux	
Toluene,	80	oC	
Toluene,	90	oC	
CH3CN,	reflux	
Toluene,	111	oC 
CH3CN,	reflux

SiO2‐NH‐Cu,	2	mol% 	
CuCl,	10	mol% 
Zn	dust,	15	mol	% 
InBr3,	10	mol% 
Nanocrystalline	Cu  
12‐tungstophosphoric	acid	30	mg	
NiCl2		
Fe(HSO4)3,	10	mol% 

4‐Chlorobenzaldehyde 2 
 
 
 
 
 

24/95	[24]	
8/81	[43]	
4/95	a	

Solventless,	r.t 
Toluene,	111	oC	
CH3CN,	reflux

SiO2‐NH‐Cu	2	mol% 	
NiCl2	5mol%	
Fe(HSO4)3,	10	mol%  

Formaldehyde	 
 

3	
	
	

24/89	[24]	
12/75	[35] 
5/84	[41]	
3/95	[42]	
5/85	a	

Solventless,	r.t.
CH3CN,	reflux	
Toluene,	90	oC	
CH3CN,	reflux	
CH3CN,	reflux	

SiO2‐NH‐Cu	2	mol% 
Zn	dust,	15	mol	% 
Nanocrystalline	Cu	
12‐tungstophosphoric	acid	30	mg	
Fe(HSO4)3,	10	mol%	

Cyclohexylaldehyde 4 
 
	

a	Present	study.	
	

	
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