Quinulinium fluorochromate C9H7NHCrO3F: An efficient and convenient reagent for the oxidative deprotection of trimethylsilyl ethers in non-aqueous conditions

Article abstract of DOI:10.1080/714040974

Primary and secondary trimethylsilyl ethers are efficiently converted to their carbonyl compound using quinolinium fluorochromate in nonaqueous conditions.

Full text of DOI:10.1080/714040974

This article was downloaded by: [Northeastern University]
On: 16 November 2014, At: 08:18
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
Phosphorus, Sulfur, and Silicon and the Related
Elements
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Quinulinium Fluorochromate C H NHCrO F: An
9
7
3
Efficient and Convenient Reagent for the Oxidative
Deprotection of Trimethylsilyl Ethers in Non-Aqueous
Conditions
a
b
a
Mahmood Tajbakhsh , Iraj Mohammadpoor-Baltork & Farhad Ramzanian-Lehmali
a
University of Mazandaran, Babolsar, Iran
b
University of Isfahan, Isfahan, Iran
Published online: 18 Jun 2010.
To cite this article: Mahmood Tajbakhsh , Iraj Mohammadpoor-Baltork & Farhad Ramzanian-Lehmali (2003) Quinulinium
Fluorochromate C H NHCrO F: An Efficient and Convenient Reagent for the Oxidative Deprotection of Trimethylsilyl
9
7
3
Ethers in Non-Aqueous Conditions, Phosphorus, Sulfur, and Silicon and the Related Elements, 178:12, 2617-2620, DOI:
0.1080/714040974
1
To link to this article: http://dx.doi.org/10.1080/714040974
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

Phosphorus, Sulfur, and Silicon, 178:2617–2620, 2003
Copyright ꢀC Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500390248231
QUINULINIUM FLUOROCHROMATE C H NHCrO F:
9
7
3
AN EFFICIENT AND CONVENIENT REAGENT
FOR THE OXIDATIVE DEPROTECTION
OF TRIMETHYLSILYL ETHERS IN
NON-AQUEOUS CONDITIONS
a
b
Mahmood Tajbakhsh, Iraj Mohammadpoor-Baltork,
a
and Farhad Ramzanian-Lehmali
a
University of Mazandaran, Babolsar, Iran and
b
University of Isfahan, Isfahan, Iran
(
Received May 24, 2003; accepted July 3, 2003)
Primary and secondary trimethylsilyl ethers are efficiently converted
to their carbonyl compound using quinolinium fluorochromate in
nonaqueous conditions.
Keywords: Deprotection; oxidative; quinoliniumfluoro chromat; trime-
thylsilyl ether
The protection of certain functional groups and the deprotection of the
protected derivatives constitute important processes in synthetic or-
ganic chemistry in polyfunctional molecules, including the total synthe-
sis of natural products. Thus, a large number of protective groups have
been developed along with numerous methods for their removal.1−5
Conversion of the hydroxy function to trimethylsilyl ether is one of
the most useful and convenient method for the protection of this func-
6−8
tional group.
Direct oxidation of trimethylsilyl ethers to their corre-
sponding carbonyl compound has found considerable attention during
9−20
recent years.
However, some of the reported methods show limitation such as use
of expensive reagents, long reaction time, low yields of the products,
and tedious work-up. Therfore, the introduction of new methods and
We are thankful to the Mazandaran and Isfahan Universities Research Council for
the partial support of this work.
Address correspondence to Mahmood Tajbakhsh, Department of Chemistry, School
of Sciences, University of Mazandaran, PO Box 453, Babolsar, Iran. E-mail: tajbakhsh@
umz.ac.ir
2
617

2
618
M. Tajbakhsh et al.
inexpensive reagents for such functional group transformation is still
in demand.
RESULTS AND DISCUSSION
We report here a new and efficient method for the cleavage of
trimethylsilyl ethers using quinoliniumfluoro chromat. This reagent
2
1
recently has been used for the oxidation of alcohols. For this purpose,
first, we have studied the oxidative deprotection of benzyltrimethylsi-
lyl ether to benzaldehyde with this reagent in common organic solvent,
such as MeCN, CH2Cl2, CHCl3, THF and n-hexane. The experimen-
tal results show that MeCN is a suitable solvent for these oxidations
(
Scheme 1) (Table I).
SCHEME 1
When a variety of trimethylsilyl ethers were treated with quinolini-
umfluoro chromat, the corresponding carbonyl compound were obtained
in excellent yields (Table II).
It is important to note that the reaction medium was almost neutral,
so that some of the sensitive functionalities such as the carbon-carbon
double bond remained intact (Table II, entry 15).
In conclusion quinoliniumfluoro chromat is a mild, efficient, and in-
expensive reagent for the one-pot oxidative deprotection of trimethylsi-
lyl ethers to the corresponding carbonyl compound in nonaqueous
condition.
TABLE I Oxidative Deprotection of
Benzyltrimethylsilyl Ether in Different Solvents
◦
Using QFC at 25 C
Entry
Solvent
Time (h)
Yield (%)a,b
1
2
3
4
5
CH2Cl2
CHCl3
THF
c-C6H12
CH3CN
2
2
2
2
45
35
30
45
92
0.6
aYields refer to isolated products as their 2,4-dinitro
phenylhydrazones.
b
Substrate/oxidant (1/1).

Deprotection of Trimethylsilyl Ethers
2619
TABLE II Oxidative Deprotection of Trimethylsilyl Ethers with QFC in
◦
CH
3
CN at 25 C
Entry
Substrate
Time (h)
Products
C6H5CHO
(C6H5)2CO
o-ClC6H4CHO
Yield (%)a
1
2
3
4
5
6
7
8
9
C6H5CH2OTMS
(C6H5)2CHOTMS
0.6
1.6
0.8
0.75
0.8
0.5
0.8
1.2
1.5
1.2
1.5
1.4
1.7
1.6
0.7
92
93
89
92
93
94
94
95
91
90
89
92
85
86
94
o-ClC6H4CH2OTMS
p-ClC6H4CH2OTMS
m-MeOC6H4CH2OTMS
p-MeOC6H4CH2OTMS
o-MeOC6H4CH2OTMS
C6H5CH(p-ClC6H4)OTMS
p-MeC6H4CH2OTMS
C6H5CH2CH2CH2OTMS
p-NO2C6H4CH2OTMS
m-NO2C6H4CH2OTMS
CH3(CH2)7OTMS
p-ClC6H4CHO
m-MeOC6H4CHO
p-MeOC6H4CHO
o-MeOC6H4CHO
C6H5C(p-ClC6H4)O
p-MeC6H4CHO
C6H5CH2CH2CHO
p-NO2C6H4CHO
p-NO2C6H4CHO
CH3(CH2)6CHO
CH3(CH2)5CHO
C6H5CH CHCHO
10
11
12
13
14
15
CH3(CH2)6OTMS
C6H5CH CHCH2OTMS
aIsolated yields.
EXPERIMENTAL
Products were isolated and their physical data were compared with
those of known samples. Solvent was freshly distilled. Trimethylsilyl
ethers were prepared according to the described procedure. QFC was
prepared according to the literature.21
General Procedure for the Oxidative Deprotection
of Trimethylsilyl Ethers with QFC
Trimethylsilyl ethers (1 mmol) was added to a stirred suspension of
QFC (0.249 g, 1 mmol) in CH3CN (15 ml). The reaction mixture was
stirred at room temperature for 0.5–1.7 h. The progress of the reaction
was monitored by TLC (eluent:hexane/ethyl acetate, 10:1). After the
reaction was complete the mixture was filtered, and the solid material
was washed with diethyl ether several times. The combined filtrate was
evaporated under reduced pressure and the resulting crude material
was purified on a silica-gel plat or silica-gel column with an appropriate
eluent. Pure compounds were obtained in 85–94% yields (Table II).
REFERENCES
[
1] M. B. Smith and Mc. Graw, Organic Synthesis, 7, 145 (1998).

2
620
M. Tajbakhsh et al.
[
2] M. Lalonde and T. H. Chan, Synthesis, 817 (1985).
[
[
3] I. Mohammadpoor-Baltork and Sh. Pouranshirvani, Synthesis, 756 (1997).
4] M. Heravi, K. Aghapoor, M. A. Nooshabadi, and M. M. Mojtahedi, Synth. Commun.,
25, 1143 (1997).
[
[
[
5] J. Muzart, Synthesis, 11 (1998).
6] H. Firouzabadi and I. Mohammadpoor-Baltork, Synth. Commun., 24, 1065 (1994).
7] K. Aghapoor, M. M. Heravi, and A. Nooshabadi, Indian J. Chem., Section B, 38, 84
(
1998).
[
[
8] H. Firouzabadi and F. Shiriny, Synth. Commun., 26, 423 (1996).
9] H. Firouzabadi and F. Shiriny, Synth. Commun., 26, 649 (1996).
[
10] J. Muzart and A. Aitajjou, Synth. Commun., 22, 1993 (1992).
[
11] M. M. Heravi, D. Ajami, K. Tabar Hydar, and M. R. Saidi, Tetrahedron Lett., 28, 125
(
1998).
[
12] M. Tajbakhsh, I. Mohammadpoor-Beltork, and F. Ramzanian-Lehmali, Chem.
Research (S), 185 (2001).
[13] M. M. Heravi, D. Ajami, and M. Gassemzadeh, Synth. Commun., 29(5), 781 (1999).
[14] M. Gurini and F. Epifano, Synth. Commun., 29, 541 (1999).
[15] T. T. Upadhya, T. Daniel, T. Sudalai, T. Ravindaranathan, and K. R. Sabu, Synth.
Commun., 26, 4539 (1996).
[16] B. S. Babu and K. K. Balasubramanian, Tetrahedron Lett., 39, 9287 (1998).
[17] K. J. Davis, U. Bhalerao, and B. V. Rao, Synth. Commun., 29, 1679 (1999).
[18] R. Ballini, F. Bigi, S. Carloni, R. Maggi, and G. Sartori, Tetrahedron Lett., 38, 4169
(
1997).
19] A. R. Hajipour, S. E. Malakpour, I. M. Baltork, and H. Adibi, Synth. Commun., 31,
625 (2001).
[
1
[
[
20] H. Firouzabadi and B. Karimi, Synth. Commun., 23, 1633 (1993).
21] V. Murugesan and A. Pandurrangan, Ind. J. Chem., 1, 31B, 377 (1992).