[HSO3-pmim][CH3SO3] as an efficient catalyst for chemoselective synthesis of 1,1-diacetates under ultrasound irradiation

Article abstract of DOI:10.2174/157017811796504945

A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by 1-methyl-3-(3- sulfopropyl)-imidazolium methyl sulfate under ultrasound irradiation has been developed. The yields are ranged in 90%-98%. This protocol offered several advantages including low catalyst loading, high yields, short reaction time and environmentally benign approach.

Full text of DOI:10.2174/157017811796504945

4
84
Letters in Organic Chemistry, 2011, 8, 484-487
[
HSO -pmim][CH SO ] as an Efficient Catalyst for Chemoselective Syn-
3
3
3
thesis of 1,1-Diacetates under Ultrasound Irradiation
1
1,2
1
1
,1
1
Chao Li , Tao Guo , Xin Zhou , Chun Wang , Jing-Jun Ma* and Jin-Bin Li
1
Hebei Key Laboratory of Bioinorganic Chemistry, College of Sciences, Agricultural University of Hebei, Baoding
0
71001, P.R. China
2
College of Information Science & Technology, Agricultural University of Hebei, Baoding 071001, P.R.
China
Received September 20, 2010: Revised March 23, 2011: Accepted April 14, 2011
Abstract: A mild and efficient method for the chemoselective preparation of 1,1-diacetates catalyzed by 1-methyl-3-(3-
sulfopropyl)-imidazolium methyl sulfateunder ultrasound irradiation has been developed. The yields are ranged in 90% ~
9
8%. This protocol offered several advantages including low catalyst loading, high yields, short reaction time and envi-
ronmentally benign approach.
Keywords: 1,1-diacetates, 1-methyl-3-(3-sulfopropyl)-imidazolium methyl sulfate, aldehydes, catalyze, synthesis, ultrasound
irradiation.
INTRODUCTION
diacetates under solvent-free conditions [11d]. And part of
information included in this article has been previously pub-
lished in our previous work.
Selective protection and deprotection of carbonyl groups are
essential steps in modern organic chemistry [1]. 1,1-
Diacetates (acylals) are one of the most useful carbonyl pro-
tecting groups due to their stability under both neutral and
basic media as well as under acidic conditions [2]. Therefore,
In recent years, ultrasound has increasingly been used in
organic synthesis. As it is known, it can accelerate diverse
types of organic reactions and it is established as an impor-
tant technique in organic synthesis. Compared with tradi-
tional methods, this method is more convenient and easily
controlled. A large number of organic reactions can be car-
ried out with a higher yield, shorter reaction time and envi-
ronmentally benign approach under ultrasonic irradiation
[12].
1
,1-Diacetates have been used as starting materials and in-
termediates in organic synthesis [3] and have also been used
as cross linking reagents for cellulose in cotton [4]. Gener-
ally, they are synthesized from acetic anhydride and alde-
hydes using strong protonic acids as catalysts, such as sulfu-
ric acid [5a], phosphoric [5b], methanesulfuric [5c] or per-
chloric acid [5d] and Lewis acids, including FeCl
6a], InCl [6b], ZrCl [6c], LiBF [6d], Cu(BF ·xH
CAN [6f], WCl [6g], Zn(BF [6h], H
6i], AlPW12 40 [6j], and heterogeneous catalysts like
Nafion-H [7a], expansive graphite [7b], zeolites [7c,d],
montmorillonite clay [7e,f,g] and supported reagents [7h,i].
Other catalysts, such as iodine [8], N-bromosuccinimide [9],
and trimethylchlorosilane/sodium iodide [10], have also been
used for this transformation. But these procedures are often
accompanied with longer reaction time, low product yields,
stringent conditions, high catalyst loading, the use of toxic
solvents and so on. Although, recently the triflates like
3
[2], PCl
3
Room temperature ionic liquids (RTILs) have received
increasing attention as potential “greener” alternatives to
volatile organic solvent, and they have been investigated
extensively as solvents or catalysts in many important or-
ganic reactions because of their special properties, such as
their negligible vapor pressure, tunable polarity, high ther-
mal stability, good solvating ability, ease of recyclability,
and their potential to enhance reaction rates and selectivity
[
3
4
4
4
)
2
2
O [6e],
6
4
)
2
6 2 18 2
P W O62·24H O
[
O
[
13]. They have also been referred as “designer solvents,” as
their properties can be altered by the fine-tuning of parame-
ters, such as the choice of organic cation, inorganic anion,
and alkyl chain attached to the organic cation. These struc-
tural variations offer flexibility to the chemist to devise the
most idealized solvent and catalyst, catering for the needs of
a particular process [14].
2 3
Cu(OTf) [11a], Sc(OTf) [11b] and LiOTf [11c] have
emerged as the most effective catalysts for the reaction, the
high cost and susceptibility to aqueous medium of the metal
triflates do not make triflates good contenders for using in
large scale synthesis. Therefore, the efficient procedures that
can overcome the shortcomings of the previous methods are
In continuing our endeavor in green synthesis and using
ionic liquids as a recyclable reaction medium to enhance
rates and selectivity [15], we report herein a mild and effi-
cient protocol for the preparation of 1,1-diacetates and their
derivatives under ultrasound irradiation using acidic ionic
liquids (1-methyl-3-(3-sulfopropyl)-imidazolium methyl
sulfate ([HSO -pmim][CH SO ])) as an efficient catalyst
also desirable. In our previous work, we selected NbCl
5
as an
efficient catalyst for chemoselective synthesis of 1,1-
*
Address correspondence to this author at the Hebei Key Laboratory of
3
3
3
Bioinorganic Chemistry, College of Sciences, Agricultural University of
Hebei, Baoding 071001, Hebei Province, P.R. China; Tel:+86 312 7528291;
Fax: +86 312 7528292; E-mail: majingjun@hebau.edu.cn
(
Scheme 1).
1
570-1786/11 $58.00+.00
© 2011 Bentham Science Publishers

[HSO
3
-pmim][CH
3
SO
3
] as an Efficient Catalyst for Chemoselective
Letters in Organic Chemistry, 2011, Vol. 8, No. 7
485
1
[
HSO -pmim][CH SO ]
3 H
Entry 3f: H NMR (CDCl , 400 MHz) ꢀ : 2.16 (s, 6H),
3
3
3
RCHO
+
Ac O
RCH(OAc)2
2
7
~
1
.32 ~ 7.35 (m, 1H), 7.45 ~ 7.52 (m, 1H), 7.67 (s, 1H), 7.89
7.92 (m, 1H). IR (KBr) ꢁ 1013, 1200, 1235, 1475, 1540,
Ultrasound Irradiation
:
1
2
3
-1
760 cm .
Entry 3g: H NMR (CDCl
.41 (s, 3H ), 7.22 (d, J = 8.0 Hz, 2H), 7.43 (d, J = 8.0 Hz,
1
R = C H , 2-ClC H , 4-ClC H , 4-FC H ,
3 H
, 400 MHz) ꢀ : 2.12 (s, 6H),
6
5
6
4
6
4
6 4
2
4
-BrC H , 2,4-2ClC H , 4-MeC H ,
2H), 7.70 (s, 1H ). IR (KBr) ꢁ 625, 778, 1015, 1210, 1248,
6
4
6
3
6
4
:
-
1
1
488, 1652, 1752, 3025, 3062 cm .
4-MeOC H , 2-NO C H , 3-NO C H ,
6
4
2
6
4
2
6
4
1
Entry 3h: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.11 (s, 6H),
3
2
.81 (s, 3H), 6.75 (d, J = 9.0 Hz, 2H), 7.38 (d, J = 9.0 Hz,
H), 7.42 (s, 1H). IR (KBr) ꢁ 930, 995, 1205, 1240, 1375,
4
-NO C H , C H CH=CH
2 6 4 6 5
:
-
1
Scheme 1.
1521,1615, 1760, 3015, 3045 cm .
1
Entry 3i: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.15 (s, 6H),
7
1
1
.55 ~ 7.62 (m, 1H), 7.63 ~ 7.69 (m, 2H), 8.03 ~ 8.08 (m,
H), 8.20 (s, 1H). IR (KBr) ꢁ 910, 975, 1015, 1202, 1260,
368, 1530, 1595, 1770, 2880, 2940 cm .
EXPERIMENTAL SECTION
:
-
1
Melting points were recorded on an electrothermal
apparatus and remained uncorrected. H-NMR (300 MHz)
spectra were determined with Brucker AVANCE 300
1
1
Entry 3j: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.11 (s, 6H),
7
.53 ~ 7.78 (m, 3H), 8.0 (d, J = 7.2 Hz, 1H), 8.23 (s, 1H ).
3 6
spectrometer (CDCl -d ) using TMS as internal standard. IR
-
1
IR (KBr) ꢁ 735, 825, 958, 1045, 1090, 1202, 1230, 1532,
1
:
spectra (cm ) were measured with a WQF-510 spectrometer.
Sonication was performed in a Shanghai Kudos -CQX
ultrasonic cleaner with a frequency of 59 kHz and a nominal
-1
752, 3095 cm .
1
Entry 3k: H NMR (CDCl , 400 MHz) ꢀ : 2.16 (s, 6H),
3
H
power 200 W. [HSO
3
-pmim][CH
3
SO
3
] was synthesized
7.70 (d, J = 8.73 Hz, 2H), 7.74 (s, 1H), 8.28 (d, J = 8.76 Hz,
2H); IR (KBr) ꢁ 850, 960, 995, 1012, 1060, 1205, 1240,
1
according to the literatures [16].
:
-
1
352, 1530, 1610, 1764, 3090 cm .
1
General Procedure
Entry 3l: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.10 (s, 6H),
5
7
1
.90 (dd, J = 16 Hz, 1H), 6.85 (d, J = 16 Hz, 1H), 7.63 ~
.13 (m, 6H). IR (KBr) ꢁ 695, 755, 958, 1015, 1115, 1212,
240, 1375, 1495, 1610, 1652, 1765, 2935, 3095 cm .
The mixture of 5 mmol aromatic aldehydes 1, 10 mmol
acetic anhydride 2 and 10 mmol% [HSO -pmim][CH SO
was stirred rapidly under ultrasound irradiation for a certain
:
3
3
3
]
-1
period of time (shown in Table 1) to complete the reaction
(
monitored by TLC). After completion, the reaction mixture
RESULTS AND DISCUSSIONS
was successively washed with 5 mL water. The products
were separated by filtering. The obtained solids were puri-
fied by recrystallization with petroleum ether/ethyl acetate.
All the products were fully characterized by IR and H NMR
spectroscopy, and melting points, which were consistent
with literature data.
To optimize the reaction conditions, initially, we tried to
convert 4-chlorobenzaldehyde (1c) to its corresponding acy-
lal with different molar ratio [HSO -pmim][CH SO ] to sub-
3 3 3
strate. The selected experiments were carried out under ultra-
sound irradiation, using diferent amounts of catalyst. When
1
1
1
0 mmol% [HSO
,1-diacetate 3c was attained. Besides, it was found that by
3 3 3
-pmim][CH SO ] was used, a high yield of
Spectroscopic Data for Compounds
1
increasing the amount of the catalyst loading, the yields kept
unchanged. Therefore, 10 mmol% [HSO -pmim][CH SO
was chosen as the optimal loading of the catalyst.
Entry 3a: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.02 (s, 6H),
3
3
3
]
7
(
1
.35 ~ 7.43 (m, 3H), 7.52 ~ 7.55 (s, 2H), 7.72 (s, 1H); IR
KBr) ꢁ 702, 758, 1015, 1065, 1210, 1245, 1378, 1470,
:
-
1
602, 1752, 3060 cm .
Since the recovery and reusability of catalyst and solvent
are highly preferable for a green process, so we investigated
the reusability and recycling of the ionic liquids. After com-
pletion of the reaction, water was added to the reaction mix-
ture, and the solid was collected by filtration. Then the prod-
1
Entry 3b: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 1.96 (s, 6H),
625, 782,
1
7
1
.12 ~ 7.36 (m, 4H), 7.78 (s, 1H). IR (KBr) ꢁ
015, 1210, 1482, 1602, 1758, 3025, 3060 cm .
:
-
1
Entry 3c: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.10 (s, 6H),
uct was obtained. The filtrate containing [HSO
pmim][CH SO
recover the ionic liquids. The recycled [HSO
pmim][CH SO
2a. The catalytic activity of [HSO
3
-
7
(
3
.37 ~ 7.44 (m, 2H), 7.45 ~ 7.48 (s, 2H), 7.68 (s, 1H). IR
622, 785, 1012, 1215, 1376, 1480, 1605, 1758,
3
3
] was concentrated under reduced pressure to
KBr) ꢁ
020, 3062 cm .
:
3
-
-
1
3
3
] was reused in the model reaction of 1a and
-pmim][CH SO ] did not
1
Entry 3d: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.12 (s; 6H),
3
3
3
7
.38 ~ 7.41 (m, 2H), 7.45 ~ 7.47 (s, 2H), 7.68 (s, 1H ). IR
show any significant decrease even after five runs. The re-
sults are shown in Table 2. The results also indicated that the
ionic liquids employed were stable under the reaction tem-
perature.
(
KBr) ꢁ
:
632, 775, 1014, 1210, 1480, 1605, 1756, 3022, 3060
-
1
cm .
1
Entry 3e: H NMR (CDCl
3
, 400 MHz) ꢀ
H
: 2.12 (s, 6H),
7
.40 ~ 7.43 (m, 2H), 7.55 ~ 7.57 (m, 2H), 7.65 (s, 1H). IR
The results indicated that the substitute groups of aro-
matic aldehyde, whether they are electro donating or with-
drawing groups, have less effect on the reaction. The reac-
(
KBr) ꢁ 81 30, 850, 910, 1012, 1065, 1210, 1375, 1595, 1756,
:
-
2
995 cm .

4
86 Letters in Organic Chemistry, 2011, Vol. 8, No. 7
Li et al.
Table 1. Condensation Reactions of Aromatic Aldehydes with Acetic Anhydride
o
lit o
Entry
Aldehydes
CHO
Time (min)
Yield (%)
M.p.( C)
M.p. ( C)
3
3
3
3
3
a
b
c
C
6
H
5
10
15
10
10
10
10
15
15
10
10
10
15
97
93
97
98
94
93
98
97
90
98
95
98
45~46
55.8~57
44~46 [17]
56~57 [5c]
79~80 [17]
50~51 [18]
91~92 [5c]
101~102 [17]
81~82 [18]
64~65 [18]
2-ClC
6
H
H
4
4
CHO
CHO
4-ClC
6
79.2~80.4
50.5~51.8
90~91.5
d
e
4-FC
4-BrC
2,4-2ClC
4-MeC
4-MeOC
6
H
4
CHO
CHO
6
H
4
3
f
6
H
3
CHO
100.5~101.5
80.5~81.5
63.5~64.2
84.5~85.5
64~64.5
3
3
g
6
H
4
CHO
h
6
H
4
CHO
3
3
i
2-NO
3-NO
4-NO
2
2
2
C
6
C
6
C
6
H
H
H
4
4
4
CHO
CHO
CHO
85.5~86.5 [5c]
63~64 [17]
j
3
k
125.2~126.5
83~84
124~125 [5c]
84~85 [19]
3
l
6 5
C H CH=CHCHO
gem-Diacetates as carbonyl surrogates for asymmetric synthesis.
Total syntheses of sphingofungins E and F. J. Am. Chem. Soc.
tion could be carried out under ultrasound irradiation
smoothly with much shorter reaction time than that of the
document methods.
2
001, 123(49), 12191-12201; (e) Trost, B. M.; Lee, C. B.; Weiss, J.
M. Asymmetric alkylation of allylic gem-dicarboxylates. J. Am.
Chem. Soc. 1995, 117, 7247-7248.
Frick, J. G.; Harper, R. J. Acetals as crosslinking reagents for cot-
ton. J. Appl. Polym. Sci. 1984, 29, 1433-1447.
(a) Tomita, M.; Kikuchi, T.; Bessho, K.; Hori, T.; Inubushi, Y.
Studies on pilocereine and related compounds. III. Synthesis of 2,
Table 2. Studies on the Reuse of the [HSO
for the Preparation of 3c
3
-pmim][CH
3 3
SO ]
[
4]
5]
[
Round
1
2
3
4 5
2
', 3-trimethoxydiphenyl ether-4', 5-and-4', 6-dicarboxaldehyde.
Yield (%)
97
95
92
90
88
Chem. Pharm. Bull. 1963, 11, 1484-1490; (b) Davey, W.; Gwilt, J.
R. Chalcones and related compounds. Part I. Preparation of nitro-,
amino-, and halogeno-chalcones. J. Chem. Soc. 1957, 1008-1014;
(
c) Freeman, F.; Karchefski, E. M. Preparation and spectral proper-
ties of benzylidene diacetates. J. Chem. Eng. Data 1977, 22(3),
55-357; (d) Marshall, J. A.; Wuts, P. G. M. Stereoselective syn-
In conclusion, we have reported a reliable, rapid and en-
vironmentally benign method for the preparation of acylals
from aldehydes and acetic anhydride under ultrasound irra-
diation. The advantages of this method are high yields, short
reaction time, low catalyst loading and solvent-free. The
application studies of the task-specific ionic liquids for other
reactions are in progress.
3
thesis of racemic occidentalol and related cis-fused hexahydron-
aphthalenes from m-toluic acid. J. Org. Chem. 1977, 42, 1794-
1
(a) Michie, J. K.; Miller, J. A. Phosphorus trichloride as catalyst in
the preparatio of 1,1-diacetates from aldehydes. Synthesis 1981,
824; (b) Yadav, J. S.; Reddy, B. V. S.; Srinivas, C. Indium trichlo-
ride catalyzed chemoselective conversion of aldehydes to gem-
diacetates. Synth. Commun. 2002, 32, 2149-2153; (c) Smitha, G.;
798.
[
6]
Reddy, C. S. A facile and efficient ZrCl
4
catalyzed conversion of
aldehydes to geminal-diacetates and dipivalates and their cleavage.
ACKNOWLEDGEMENTS
Tetrahedron 2003, 59, 9571-9576; (d) Yadav, J. S.; Reddy, B. V.
S.; Venugopal, C.; Ramalingam, T. LiBF -Mediated conversion of
4
This project was sponsored by the Nature Development
Foundation of Hebei Province (B2011204051), the Devel-
opment Foundation of the Department of Education of Hebei
Province (2010137), and the Research Development Founda-
tion of the Agricultural University of Hebei.
aldehydes to gem-diacetates. Synlett 2002, 604-606; (e) Chak-
raborti, A. K.; Thilagavathi, R.; Kumar, R. Copper(II) tetra-
fluoroborate-catalyzed formation of aldehyde-1,1-diacetates. Syn-
thesis 2004, 831-833; (f) Roy, S. C.; Banerjee, B. A mild and effi-
cient method for the chemoselective synthesis of acylals from alde-
hydes and their deprotections catalysed by ceric ammonium nitrate.
Synlett 2002, 1677-1678; (g) Karimi, B.; Ebrahiminan, G. R.; Se-
radj, H. Highly efficient and chemoselective conversion of alde-
REFERENCES
[
1]
Green, T. W.; Wuts, P. G. M. Protective groups in organic synthe-
sis. Thirded., Wiley, New York, 1999.
Kochhar, K. S.; Bal, B. S.; Deshpande, R. P.; Rajadhyaksha, S. N.;
Pinnick, H. W. Protecting groups in organic synthesis. Part 8. Con-
version of aldehydes into geminal diacetates. J. Org. Chem. 1983,
6
hyde to acylals catalyzed with tungsten hexachloride (WCl ).
Synth. Commun. 2002, 32, 669-673; (h) Ranu, B. C.; Dutta, J. Zinc
tetrafluoroborate-catalyzed efficient conversion of aldehydes to
geminal diacetates and cyanoacetates. Chem. Lett. 2003, 32, 366-
367; (i) Romanelli, G. P.; Thomas, H. J.; Baronetti, G. T.; Autino,
J. C. Solvent-free catalytic preparation of 1,1-diacetates from alde-
hydes using a Wells–Dawson acid (H P W O62·24H O). Tetrahe-
6 2 18 2
dron Lett. 2003, 44, 1301-1303; (j) Firouzabadi, H.; Iranpoor, N.;
Nowrouzi, F.; Amani, K. Aluminum dodecatungstophosphate
(AlPW12O40) as an efficient heterogeneous inorganic catalyst for
[
2]
4
8, 1765-1767.
[
3]
(a) Sandbery, M.; Sydnes, L. K. Cyanohydrin esters from acylals
with cyanide reagents. Org. Lett. 2000, 2(5), 687-689; (b) Sand-
berg, M.; Sydnes, L. K. Formation of nitriles by treatment of acy-
lals with trimethylsilyl azide in the presence of a Lewis acid. Tet-
rahedron Lett. 1998, 39, 6361-6364; (c) Van Heerden, F. R.;
Huyser, J. J.; Williams, D. B. G.; Holzapfer, C. W. Palladium-
catalysed substitution reactions of geminal allylic diacetates. Tetra-
hedron Lett. 1998, 39, 5281-5284; (d) Trost, B. M.; Lee, C. B.
the chemoselective synthesis of geminal diacetates (acylals) under
solvent-free conditions. Tetrahedron Lett. 2003, 44, 3951-3954.
(a) Olah, G. A.; Mehrotra, A. K. Catalysis by solid superacid; 16 .
1
[7]
Improved nafion-H-catalyzed preparation of 1,1-diacetates from

[HSO
3
-pmim][CH
3
SO
3
] as an Efficient Catalyst for Chemoselective
Letters in Organic Chemistry, 2011, Vol. 8, No. 7
487
aldehydes. Synthesis 1982, 962-963; (b) Jin, T. S.; Du, G. Y.;
Zhang, Z. H.; Li, T. S. An efficient and convenient procedure for
preparation of 1,1-diacetates from aldehydes catalysed by expan-
sive graphite. Synth. Commun. 1997, 27, 2261-2266; (c) Ballini, R.;
Bordoni, M.; Bosica, G.; Maggi, R.; Sartori, G. Solvent free syn-
thesis and deprotection of 1,1-diacetates over a commercially
available zeolite Y as a reusable catalyst. Tetrahedron Lett. 1998,
ultrasound. Tetrahedron Lett. 2005, 46, 2483-2485; (d) Li, J. T.; Li,
T. S.; Li, L. J.; Cheng, X. Synthesis of ethyl ꢀ-cyanocinnamates
under ultrasound irradiation. Ultrason. Sonochem. 1999, 6(4), 199-
201.
[13]
[14]
(a) Welton, T. Chem. Rev. Room-temperature ionic liquids. sol-
vents for synthesis and catalysis. 1999, 99, 2071-2083; (b) Dupont,
J.; de Souza, R. F.; Suarez, P. A. Z. Ionic liquid (molten salt) phase
organometallic catalysis. Chem. Rev. 2002, 102, 3667-3692; (c)
Jaina, N.; Kumara, A.; Chauhana, S.; Chauhan, S. M. S. Chemical
and biochemical transformations in ionic liquids. Tetrahedron.
2005, 61, 1015-1060; (d) Chowdhury, S.; Mohan, R. S.; Scott, J. L.
Reactivity of ionic liquids. Tetrahedron 2007, 63, 2363-2389.
(a) Lee, S. G. Functionalized imidazolium salts for task-specific
ionic liquids and their applications. Chem. Commun. 2006, 10,
1049-1063; (b)Ranu, B. C.; Banerjee, S. Ionic liquid as catalyst and
reaction medium. The dramatic influence of a task-specific ionic
liquid, [bmIm]OH, in Michael addition of active methylene com-
pounds to conjugated ketones, carboxylic esters, and nitriles. Org.
Lett. 2005, 7, 3049-3052; (c) Zhu, A. L.; Jiang, T.; Wang, D.; Han,
B. X.; Liu, L.; Huang, J.; Zhang, J. C.; Sun, D. H. Direct aldol reac-
tions catalyzed by 1,1,3,3-tetramethylguanidine lactate without sol-
vent. Green Chem. 2005, 7, 514-517.
3
9, 7587-7590; (d) Pereira, C.; Gigante, B.; Marcelo-Curto, M. J.;
Carreyre, H.; Pérot, G.; Guisnet, M. Diacetates from aldehydes in
the presence of zeolites. Synthesis 1995, 1077-1078; (e) Zhang, Z.
H.; Li, T. S.; Fu, C. G. Montmorillonite clay catalysis. Part 4.1 An
efficient and convenient procedure for preparation of 1,1-diacetates
from aldehydes. J. Chem. Res. Synop. 1997, 174-175; (f) Li, T. S.;
Zhang, Z. H.; Gao, Y. J. A rapid preparation of acylals of alde-
3
hydes catalysed by Fe -montmorillonite synthetic communications:
An international journal for rapid communication of synthetic or-
ganic Chemistry. Synth. Commun. 1998, 28, 4665-4671; (g) Nagy,
N. M.; Jakab, M. A.; Konya, J.; Antus, S. Convenient preparation
of 1,1-diacetates from aromatic aldehydes catalysed by zinc-
montmorillonite. Appl. Clay Sci. 2002, 21, 213-216; (h) Li, Y. Q.;
Cheng, L. H. A rapid and convenient synthesis of acylals from al-
4 2
dehydes and acetic anhydrides catalyzed by SnCl /SiO . Chin.
Chem. Lett. 2001, 12, 565-568; (i) Li, Y. Q. A rapid and convenient
synthesis of 1,1-diacetates from aldehydes and acetic anhydride
[15]
(a) Ma, J. J.; Zhou, X.; Zang, X. H.; Wang, C.; Wang, Z.; Li, J. C.;
Li, Q. A green and efficient synthesis of 9-aryl-3,4,5,6,7,9-
hexahydroxanthene-1,8-dione using a task-specific ionic liquid as
dual catalyst and solvent. Aus. J. Chem. 2007, 60, 146-148; (b) Ma,
J. J.; Gao, S. T.; Li, Z.; Tang, R. X.; Liu, H. Y.; Wang, C.; Gao, Y.
Synthesis of 5-arylmethylidene-2-thio-4-thiazolidinone derivatives
catalyzed by alkaline ionic liquid. Chin. J. Org. Chem. 2008, 28(2),
339-342; (c) Ma, J. J.; Zang, X. H.; Zhou, X.; Wang, C.; Li, J. C.;
Li, Q. One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones ca-
talyzed by acidic ionic liquid. Indian J. Chem. Sec B 2007, 46(B),
2045-2048; (d) Wang, C.; Ma, J. J.; Zhou, X.; Zang, X. H.; Wang,
Z.; Gao, Y. J.; Cui, P. L. 1-n-Butyl-3-methylimmidazolium tetra-
fluoroborate-promoted green synthesis of 5-arylidene barbituric a-
cids and thiobarbituric acid derivatives. Synth. Commun. 2005, 35,
2759-2764.
3
catalyzed by PVC-FeCl catalyst. Synth. Commun. 2000, 30(21),
3
913-3917.
[
[
[
[
8]
Deka, N.; Kalita, D. J.; Borah, R.; Sarma, J. C. Iodine as acetyla-
tion catalyst in the preparation of 1,1-diacetates from aldehydes. J.
Org. Chem. 1997, 62, 1563-1564.
Karimi, B.; Seradj, H.; Ebrahimian, G. R. Mild and efficient con-
version of aldehydes to 1,1-diacetates catalyzed with N-
bromosuccinimide (NBS). Synlett. 2000, 623-624.
Deka, N.; Borah, R.; Kalita, D. J.; Sarma, J. C. Synthesis of 1,1-
diacetates from aldehydes using trimethylchlorosilane and sodium
iodide as catalyst. J. Chem. Res. Synop. 1998, 94-95.
(a) Chandra, K. L.; Saravanan, P.; Singh, V. K. An efficient me-
thod for diacetylation of aldehydes. Synlett 2000, 359-360; (b) Ag-
9]
10]
11]
garwal, V. K.; Fonquerna, S.; Vennall, G. P. Sc(OTf)
3
, an efficient
[16]
Zhang, L.; Xian, M.; He, Y. C.; Li, L. Z.; Yang, J. M.; Yu, S. T.;
Xu, X. A Brønsted acidic ionic liquid as an efficient and environ-
mentally benign catalyst for biodiesel synthesis from free fatty ac-
ids and alcohols. Bioresour. Technol. 2009, 100, 4368-4373.
Jin, T. S.; Sun, G. ; Li, Y. W.; Li, T. S. An efficient and convenient
procedure for the preparation of 1,1-diacetates from aldehydes ca-
catalyst for formation and deprotection of geminal diacetates (acy-
lals); chemoselective protection of aldehydes in presence of ke-
tones. Synlett 1998, 849-850; (c) Karimi, B.; Maleki, J. Lithium
trifluoromethanesulfonate (LiOTf) as a recyclable catalyst for
highly efficient acetylation of alcohols and diacetylation of alde-
hydes under mild and neutral reaction conditions. J. Org. Chem.
[17]
[18]
2 3
talyzed by H NSO H. Green Chem. 2002, 4, 255-258.
2
003, 68(12), 4951-4954. (d) Gao, S. T.; Zhao Y.; Li C.; Ma J. J.;
Wang C. NbCl as an efficient catalyst for chemoselective synthe-
sis of 1,1-diacetates under solvent-free conditions. Synth. Commun.
009, 39(12), 2221-2229.
Yin, L.; Zhang, Z.-H.; Wang, Y.-M.; Pang, M.-L. Indium Tribro-
mide as a Highly Efficient and Versatile Catalyst for Chemoselec-
tive Synthesis of Acylals from Aldehydes under Solvent-Free Con-
ditions. Synlett. 2004, 1727-1730.
5
2
[12]
(a) Mason, T. J.; Lorimer, J. P. In: Applied Sonochemistry. The
Uses of Power Ultrasound in Chemistry and Processing, Wiley-
VCH: Weinheim, 2002; (b) Zhang, S. M.; Li, H.; Zheng, X. C.; Li,
B. Q.; Wu, S. H.; Huang, W. P.; Liu, Z. G.; Feng, Y. Application of
ultrasound in organic reaction. Chin. J. Org. Chem. 2002, 22, 603-
[19]
Hajipour, A. R.; Zarei, A.; Khazdooz, L.; Bi Bi Mirjalili, F.; Sheik-
han, N.; Zahmatkesh, S.; Ruoho, A. E. Silica Sulfuric Acid as an
Efficient Heterogeneous Catalyst for the Synthesis of 1,1-
Diacetates under Solvent-Free Conditions. Synthesis 2005, 3644-
3648.
6
09; (c) Ambulgekar, G. V.; Bhanage, B. M.; Samant, S. D. Low
temperature recyclable catalyst for Heck reactions using