Synthesis of 1,1-diacetates using a new combined catalytic system: Copper p-toluenesulfonate/HOAc

Article abstract of DOI:10.1080/00397910701845720

Copper p-toluenesulfonate acetic acid has been established as an efficient combined catalytic system for chemoselective conversion of aldehydes to diacetates in high yields at ambient temperature in short reaction times. For the catalytic system, the amount of copper p-toluenesulfonate reduced to 0.3 mol%. After the reaction, copper p-toluenesulfonate can be easily recovered and reused for at least 10 runs. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910701845720

This article was downloaded by: [Lulea University of Technology]
On: 06 August 2013, At: 13:14
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office:
Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An International
Journal for Rapid Communication of
Synthetic Organic Chemistry
Publication details, including instructions for authors and subscription
information:
http://www.tandfonline.com/loi/lsyc20
Synthesis of 1,1‐Diacetates using a New
Combined Catalytic System: Copper
p‐Toluenesulfonate/HOAc
a
b
c
c
Min Wang , Zhiguo Song , Hong Gong & Heng Jiang
a
College of Chemistry and Chemical Engineering, Bohai University, Jinzhou,
Liaoning, China
b
Center for Science and Technology Experiment, Bohai University, Jinzhou,
Liaoning, China
c
Liaoning Shihua University, Fushun, Liaoning, China
Published online: 22 Feb 2008.
To cite this article: Min Wang , Zhiguo Song , Hong Gong & Heng Jiang (2008) Synthesis of 1,1‐Diacetates
using a New Combined Catalytic System: Copper p‐Toluenesulfonate/HOAc, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 38:6, 961-966, DOI:
10.1080/00397910701845720
To link to this article: http://dx.doi.org/10.1080/00397910701845720
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”)
contained in the publications on our platform. However, Taylor & Francis, our agents, and our
licensors make no representations or warranties whatsoever as to the accuracy, completeness, or
suitability for any purpose of the Content. Any opinions and views expressed in this publication
are the opinions and views of the authors, and are not the views of or endorsed by Taylor &
Francis. The accuracy of the Content should not be relied upon and should be independently
verified with primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities
whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or
arising out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any substantial
or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or
distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use
can be found at http://www.tandfonline.com/page/terms-and-conditions

w
Synthetic Communications , 38: 961–966, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701845720
Synthesis of 1,1-Diacetates using a New
Combined Catalytic System: Copper
p-Toluenesulfonate/HOAc
1
Min Wang, Zhiguo Song, Hong Gong, and Heng Jiang
2
3
3
1
College of Chemistry and Chemical Engineering, Bohai University,
Jinzhou, Liaoning, China
2
Center for Science and Technology Experiment, Bohai University,
Jinzhou, Liaoning, China
3
Liaoning Shihua University, Fushun, Liaoning, China
Abstract: Copper p-toluenesulfonate acetic acid has been established as an efficient
combined catalytic system for chemoselective conversion of aldehydes to diacetates
in high yields at ambient temperature in short reaction times. For the catalytic
system, the amount of copper p-toluenesulfonate reduced to 0.3 mol%. After the
reaction, copper p-toluenesulfonate can be easily recovered and reused for at least
10 runs.
Keywords: acetic acid, copper p-toluenesulfonate, diacetates
INTRODUCTION
Recently, the synthesis, characterization, and use of sulfonates in organic
Properties such as low toxicity,
[1–3]
synthesis have received much attention.
moisture tolerance, and reusability make them attractive alternatives to conven-
tional Lewis acids. We have shown that copper methanesulfonate (CMS)–
[4]
HOAc is an excellent catalyst for diacetoxylation. Although the procedure
achieved satisfactory results, 2 mol% CMS and longer reaction times were
Received June 8, 2007
Address correspondence to Min Wang, College of Chemistry and Chemical
Engineering, Bohai University, Jinzhou, Liaoning 121000, China. E-mail:
minwangszg@yahoo.com.cn
9
61

9
62
M. Wang et al.
Scheme 1.
required. We now report a new catalytic system, copper p-toluenesulfonate
CPTS)–HOAc, which is significantly cheaper and more efficient than CMS–
(
HOAc. The amount of CPTS is only 0.3 mol%. The new catalytic system
catalyzed more aldehydes in shorter reaction times. As a continuation of our
study, we report an extension of the methodology to diacetoxylation in this
article (Scheme 1).
RESULTS AND DISCUSSION
Table 1 showed the results of different copper salts used alone or corporately
with HOAc in a model reaction of benzaldehyde (15 mmol) and Ac O
2
. .
30 mmol). Cu(NO3)2 3H O, CuCl 2H O, Cu(acac) and Cu(OAc) H O
2 2 2 2 2
.
(
2
were inert in this reaction. Neither 0.3 mol% sulfonate nor 12 mmol HOAc
alone catalyzed the formation of the product. A powerful synergistic effect
was observed when sulfonate mixed with HOAc. CPTS–HOAc gave the best
result. For CPTS–HOAc, a study revealed that increasing HOAc greatly
improved the reaction rate. Both CPTS and HOAc are indispensable for the
rate acceleration of this reaction. Individually they did not produce the same
results.
A variety of aliphatic and aromatic aldehydes were converted into 1,1-dia-
cetates smoothly under the optimal condition of aldehyde, 15 mmol; Ac O,
2
a
Table 1. Screening of copper salts for the diacetoxylation reaction
b
Yield (%)
Entry
CuX
2
Time (h) Cat.: CuX
54
2
2
Cat.: CuX –HOAc
c
1
2
3
4
5
6
7
8
9
None
Cu(NO3)2 3H O
0
0
.
2
0
0
0
0
0
0
0
0
2
.
CuCl
2
2H
2
O
2
0
Cu(acac)
Cu(OAc)2 H O
2
2
0
.
2
0
2
.
Cu(CH
Cu(C
Cu(o-CH
Cu(p-CH C H SO ) 6H O
3
SO
3
)
2
4H
2
O
0.7
0.7
0.7
0.7
36
81
91
92
.
6
H
5
SO
3 2 2
) 6H O
.
3 6 4 3 2 2
C H SO ) 4H O
.
3
6
4
3 2
2
a
CuX 0.045 mmol, HOAc 12 mmol.
2
b
Isolated yields.
Only 12 mmol of HOAc was used.
c

Synthesis of 1,1-Diacetates
963
Table 2. CPTS–HOAc catalyzed conversion of aldehydes to 1,1-diacetates
Mp (8C) or bp (torr)
Time Yield
a
(%)
Entry
Substrate
(h)
Observed
Reported
[
[
[
[
5]
6]
5]
6]
1
2
3
4
5
6
7
8
9
C
6
H
5
CHO
0.7
1
92
96
44–45
55–56
44–46
56–57
64–65
79–80
2-ClC CHO
4
6
H
3-ClC H CHO
6
1.5
2.5
2
93
92
64–65
79–80
4
4-ClC
2,4-Cl
6
H
4
CHO
CHO
[
[
5]
6]
2
C
6
H
3
92
90
98–100
72–74
101–102
[
[
[
6]
6]
5]
2-CH OC H CHO
0.5
0.7
1
74–75
64–65
81–82
3
3
3
6
6
4
4-CH
4-CH
OC
H
4
CHO
94
90
62–63
80–82
C
6
H
4
CHO
4-NO C H CHO
2 6 4
4
74
91
120–122
50–52
124–125
[
5]
52–53
92–94/19
1
1
1
1
1
1
1
1
1
1
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
2-Furaldehyde
CH CH 55 CHCHO
PhCH 55 CHCHO
0.5
0.5
1.5
1.5
4
[
7]
3
94
95
88–90/15
82–84
[
5]
85–86
[
8]
PhCH CHO
2
93
76
185–188/7
70–73/18
125–126
186–188/7
72–74/20
[
7]
CH
CH
3
CH
CH
2
2
CHO
CH CHO
[
9]
3
2
1.5
3
94
81
126
[
10]
(CH ) CHCHO
2
182–184/630 183/630
3
b
b
b
[10]
2-OHC
4-OHC
6
H
H
4
4
CHO
CHO
5
72
75
101–103
90–91
91–92
—
100–102
[10]
6
5
90–91
89–91
[10]
4-OH-3-CH OC H CHO
3 6 3
4
81
4-(CH
Cyclohexanone
CHO þ C
3
)
2
NC
6
H
4
CHO
5
0
—
—
—
5
1.5
0
—
—
c
C
6
H
5
6
H
5
COCH
3
100 þ 0
a
b
c
1
Isolated yields. The purity of the products was determined by H NMR and GC.
Four equiv. of Ac O were used.
Equimolar mixture of benzaldehyde and acetophenone; the percentages of the
2
products in the reaction mixtures were determined by GC analysis.
3
0 mmol; CPTS, 0.045 mmol; and HOAc, 12 mmol (Table 2). The products
were obtained in excellent yields with high chemoselectivity. Steric
hindrance seems to have no effects on the efficiency of this transformation,
shown in entries 2–5. Aromatic aldehydes with an electron-withdrawing
group such as nitro required a comparatively longer reaction time (entry 9).
The sensitive heteroaromatic furfural, crotonaldehyde, and cinnamaldehyde
were converted to the corresponding 1,1-diacetates successfully (entries
1
0–12). We investigated the reaction of 2-hydroxybenzaldehyde, 4-hydroxy-
benzaldehyde, and vanillin with 4 equiv. of Ac O and observed that both
2
carbonyl and phenolic hydroxyl were acylated (entries 17–19). The chemos-
electivity amount of this process was demonstrated using equimolar amounts
of benzaldehyde and acetophenone (entry 22). Smooth conversion of the
aldehyde to the corresponding diacetate was observed, while the ketone
remained unaffected.

9
64
M. Wang et al.
Table 3. Reuse of CPTS for synthesis of benzyli-
a
dene diacetate
b
Run
Yield (%)
1
2
3
4
5
6
7
8
9
92
94
93
92
93
92
94
93
95
93
1
0
a
b
Reaction time 1 h; HOAc 12 mmol.
Yields were analyzed by GC.
These observations are consistent with the effect of Brønsted-assisted
Lewis acid catalysis. It is impossible to form p-toluenesulfonic acid because
the pKa value of HOAc is higher than that of p-toluenesulfonic acid.
The catalytic system favors the formation of a ternary complex of
CPTS, aldehyde, and acid. In this complex, the aldehyde experiences
2
þ
double activation through coordination of the Lewis acid Cu
and
through hydrogen bonding with the acid proton. These interactions would
facilitate electrophilic attack into the aldehyde. A similar activation
[11]
[12]
scheme had been described by Ciufolini et al.,
[
Ishihara et al.
Mouhtady et al.,
and
13]
CPTS is blue crystal catalyst that is insoluble or slightly soluble in
reactants and products in this reaction. To demonstrate the recyclability of
CPTS, 2 mol% CPTS was used in a model reaction of benzaldehyde and
Ac O to facilitate its recovery. After the reaction, the organic phase was
2
extracted by CH Cl . CPTS could be recovered by filtration and washed
2
2
with CH Cl , then reused for its next run (Table 3). Compared with the
2
2
fresh catalyst, no decrease of catalytic activity was detected after 10 runs.
CONCLUSION
In conclusion, we have demonstrated a combined catalyst, CPTS–HOAc, for
the chemoselective conversion of aldehydes to 1,1-diacetates. The CPTS was
easily recovered and reused following the reaction, thus providing an atom
economic diacetoxylation reaction. The new combined catalytic system is
superior to the previously reported method and overcomes the problems
encountered with the classical catalyst. The new catalytic family might

Synthesis of 1,1-Diacetates
965
broaden the application of alkylsulfonates in organic synthesis. The extension
of this work to other reactions is being carried out in our laboratory.
EXPERIMENTAL
Typical Procedures
A mixture of aldehyde (15 mmol), Ac O (30 mmol), CPTS (0.045 mmol), and
2
HOAc (12 mmol) was stirred at ambient temperature for an appropriate time
(monitored by gas chromatograph (GC)). After the reaction, most of the
mixture solidified gradually, and 30 mL of CH Cl were added to dissolve
2
2
the solid product. The organic layer was washed twice with saturated
NaHCO solution (20 mL), dried (Na SO ), and evaporated to yield the
3
2
4
almost-pure product. The product was purified further by crystallization
from cyclohexane or by flash-column chromatography on silica gel (ethyl
acetate/hexane, 1:9 as the eluent). All the acylals were characterized by IR,
1
H NMR, and elemental analysis.
REFERENCES
1
2
3
4
5
. Wang, M.; Wang, Z. C.; Sun, Z. L.; Jiang, H. Reaction-controlled recovery of the
copper (II) methanesulfonate catalyst for esterification. React. Kinet. Catal. Lett.
2005, 84, 223–228.
. Wang, M.; Wang, Z. C.; Sun, Z. L.; Jiang, H. Synthesis and characterization of
transition metal methanesulfonates and their catalytic behavior in Biginelli
reactions. Transition Met. Chem. (London) 2005, 30, 792–796.
. Zhang, L. H.; Jiang, H.; Gong, H.; Sun, Z. L. Characteristics of thermal decompo-
sition products of rare earth, alkali earth metal and transition metal p-toluenesul-
fonates. J. Therm. Anal. Calorim. 2005, 79, 731–735.
. Wang, M.; Gong, H.; Jiang, H.; Wang, Z. C. Acetic acid–assisted copper metha-
nesulfonate catalyst for chemoselective conversion of aldehydes to acylals. Synth.
Commun. 2006, 36, 1953–1960.
. Jin, T. S.; Sun, G.; Li, Y. W.; Li, T. S. An efficient and convenient procedure for
2 3
the preparation of 1,1-diacetates from aldehydes catalyzed by H NSO H. Green
Chem. 2002, 4, 255–256.
. Freeman, F.; Karchefski, E. M. Preparation and spectral properties of benzylidene
diacetates. J. Chem. Eng. Data. 1977, 22, 355–357.
. Pereira, C.; Gigante, B.; Marcelo-Curto, M. J.; Carreyre, H.; P e´ rot, G.; Guisnet, M.
Diacetates from aldehydes in the presence of zeolites. Synthesis 1995, 1077–1078.
. Yadav, J. S.; Reddy, B. V. S.; Srinivas, C. Indium trichloride–catalyzed chemo-
selective conversion of aldehydes to gem-diacetates. Synth. Commun. 2002, 32,
6
7
8
2169–2174.
9
. Eshghi, H.; Gordi, Z. Phosphorus pentoxide–montmorillonite K-10 as catalyst for
the preparartion of 1,1-diacetates under solvent-free conditions. Phosphorus,
Sulfur Silicon Relat. Elem. 2004, 179, 1341–1346.

9
66
M. Wang et al.
1
0. Hajipour, A. R.; Zarei, A.; Ruoho, A. E. P
2
O
5
/Al
2
O
3
as an efficient heterogeneous
catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free
conditions. Tetrahedron Lett. 2007, 48, 2881–2884.
1
1
1
1. Ciufolini, M. A.; Deaton, M. V.; Zhu, S. R.; Chen, M. Y. A remarkable ene-like
reaction: Development and synthetic applications. Tetrahedron. 1997, 53,
1
6299–16312.
2. Mouhtady, O.; Gaspard-Houghmane, H.; Roques, N.; Roux, C. L. Metal triflates–
methanesulfonic acid as new catalytic systems: Application to the Fries rearrange-
ment. Tetrahedron Lett. 2003, 44, 6379–6382.
3. Ishihara, K.; Yamamoto, H. Brønsted acid–assisted chiral Lewis acid (BLA)
catalysis for asymmetric Diels–Alder reaction. J. Am. Chem. Soc. 1994, 116,
1
561–1562.