Efficient regeneration of aldehydes from their corresponding 1,3-oxathiolanes in the absence of solvent

Article abstract of DOI:10.1016/j.cclet.2010.10.034

A mild and efficient method for the oxidative deprotection of 1,3-oxathiolanes with Fe(NO₃)₃·9H₂O and Cu(NO₃)₂·3H₂O in the absence of solvent is reported.

Full text of DOI:10.1016/j.cclet.2010.10.034

Available online at www.sciencedirect.com
Chinese Chemical Letters 22 (2011) 421–423
www.elsevier.com/locate/cclet
Efficient regeneration of aldehydes from their corresponding
,3-oxathiolanes in the absence of solvent
1
*
Farhad Shirini , Seyyedeh Kobra Mirhashemi, Aysa Pourvali, Masoumeh Abedini
Department of Chemistry, College of Science, University of Guilan, Rasht 41335, Islamic Republic of Iran
Received 1 July 2010
Available online 15 January 2011
Abstract
A mild and efficient method for the oxidative deprotection of 1,3-oxathiolanes with Fe(NO
3
)
3
Á9H
2
O and Cu(NO
3
)
2
Á3H
2
O in the
absence of solvent is reported.
2010 Farhad Shirini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
#
Keywords: Oxidative deprotection; 1,3-Oxathiolanes; Cu(NO
3
)
2
Á3H
2
O; Fe(NO
3
)
3
2
Á9H O; Solvent-free conditions
Protection and deprotection of organic functions are important processes during multi-step organic synthesis
1]. The choice of a method which is used for the functional group transformations depends on its simplicity,
[
highest yields of the desired products, short reaction times, low cost of the process and ease of the work-up
procedure.
Oxathioacetalization of is important reaction widely used for the protection of carbonyl group during a multi-step
organic synthesis [1]. Direct oxidative deprotection of 1,3-oxathiolanes to their corresponding carbonyl compounds is
of value to synthetic organic chemists and have attracted much attentions. There are several reagents available for
deprotection of 1,3-oxathiolanes, which of them isoamyl nitrate [2], chloramine-T [3], TMSOTf [4], TMSOTf/p-
nitorbenzaldehyde [5], polymer-supported p-nitrobenzaldehyde [6], NCS-AgNO [7], I -AgNO [8], NBS [9],
3
2
2
glyoxylic acid/Amberlyst-15/MW [10] and V(HSO ) [11] are examples. Although these methods are suitable for
4
3
many synthetic conditions, the disadvantages, such as long reaction times, tedious work-up, low yields of the products,
unavailability of the reagents, use of expensive reagents, use of large amounts of the reagents and, in some cases,
inapplicability in deprotection of non-benzylic oxathiolanes, clearly identified a need to introduce new methods for
such functional group transformations.
1
. Experimental
Chemicals were purchased from Fluka, Merck and Aldrich Chemical Companies. Yields refer to isolated products.
Products were characterized by their physical constants, comparison with authentic samples [12] and IR and NMR
*
Corresponding author.
E-mail address: shirini@guilan.ac.ir (F. Shirini).
1001-8417/$ – see front matter # 2010 Farhad Shirini. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
doi:10.1016/j.cclet.2010.10.034

422
F. Shirini et al. / Chinese Chemical Letters 22 (2011) 421–423
Table 1
Regeneration of aldehydes in the absence of solvent
a,b
.
Entry
Product
Fe(NO
3
)
3
2
Á9H O
Cu(NO
3
)
2
2
Á3H O
Time (min)
Yield (%)
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
9
PhCHO
15
10
5
92
95
90
92
90
95
90
87
90
85
90
90
90
92
80
85
90
9
5
90
95
92
90
85
95
92
85
92
90
90
87
90
90
85
90
92
2-ClC
3-ClC
4-ClC
6
6
6
H
H
H
4
4
4
CHO
CHO
CHO
5
6
6
6
2-BrC H
4
CHO
3
5
2-NO
3-NO
4-NO
2
C6H4CHO
25
6
13
9
2
C
C
6
H
H
4
4
CHO
CHO
2
6
15
5
7
2-MeC
3-MeC
4-MeC
6
6
6
H
H
H
4
CHO
4
CHO
4
CHO
6
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
2
5
5
4
4-Me
2
CHC
6
H
4
CHO
CHO
CHO
3
5
2-MeOC
3-MeOC
Furfural
6
H
H
4
4
5
7
6
8
5
45
35
14
10
20
15
16
10
PhCH(Me)CHO
PhCH CH CHO
PhCOMe
2
2
c
c
–
–
a
b
c
Products were characterized by their physical constants, comparison with authentic samples and IR and NMR spectroscopy.
Yields are based on isolated products.
Mixture of unidentified products.
spectroscopy. The purity determination of the substrates and reaction monitoring were accompanied by TLC on silica
gel polygram SILG/UV 254 plates.
General procedure: A mixture of the substrate (1 mmol), 0.06 g Fe(NO ) Á9H O (0.15 mmol) and/or 0.02 g
3
3
2
Cu(NO ) ÁH O (0.1 mmol) was heated in an oil bath (90 8C) for the specified time (Table 1). The progress of the
3
2
2
reaction was monitored by TLC. After completion of the reaction, the mixture was diluted with 10 mL CH Cl and
2
2
filtered. The solid residue was washed with 5 mL CH Cl . The organic layer was washed with 2 Â 5 mL saturated
2
2
NaHCO , and 10 mL water, and dried our MgSO . Evaporation of the solvent followed by column chromatography on
3
4
silica gel gave the corresponding carbonyl compounds in good to high yields.
Typical procedure: A mixture of 2-phenyl-1,3-oxathiolane (1 mmol) (Table 1, entry 1), 0.06 g Fe(NO ) Á9H O
3
3
2
(
0.15 mmol) and/or 0.02 g Cu(NO ) ÁH O (0.1 mmol) was heated in an oil bath (90 8C) for the specified time (Table
3
2
2
1
1
2
). The progress of the reaction was monitored by TLC. After completion of the reaction, the mixture was diluted with
0 mL CH Cl and filtered. The solid residue was washed with 5 mL CH Cl . The organic layer was washed with
2
2
2
2
 5 mL saturated NaHCO , and 10 mL water, and dried our MgSO . Evaporation of the solvent followed by column
3
4
chromatography on silica gel gave benzaldehyde in 92% and/or 90% yields, respectively.
2
. Results and discussion
In continuation of our ongoing research program on the development of the applications of metal nitrates in organic
reactions [13–16], we have found that Fe(NO ) Á9H O and Cu(NO ) Á3H O can be used as efficient reagents for the
3
3
2
3 2
2
oxidative deprotection of 1,3-oxathiolanes to their corresponding carbonyl compounds. All reactions were performed
in the absence of solvent at 90 8C in good to high yields (Scheme 1).
[()TD$FIG]
Fe(NO ) 9H O (0.15 mmol) and / or
3
3.
2
O
S
Cu(NO ) 3H O (0.1 mmol)
3
2.
2
R
RCHO
Solvent-free, 90 O
C
Scheme 1.

F. Shirini et al. / Chinese Chemical Letters 22 (2011) 421–423
423
Yields and reaction times are tabulated in Table 1. Benzylic 1,3-oxathiolanes, including electron donating and
withdrawing groups are oxidized to their corresponding aldehydes in high yields (Table 1). Substrates containing the
ethereal linkages are efficiently converted to their corresponding aldehydes without cleavage of carbon–oxygen bond
(
Table 1, entries 13–15). This method is also very effective for the oxidation of aliphatic 1,3-oxathiolanes (Table 1,
entries 16 and 17). Because of the formation of unidentified products, the method is not useful for regeneration of
ketones from their 1,3-oxariolanes (Table 1, entry 18). Over-oxidation of the products to their carboxylic acids or
esters was not observed by this method.
In conclusion, in this study we have developed a mild and efficient method for the regeneration of aldehydes from
the related 1,3-oxathiolanes in the absence of solvent. Good to high yields of the products, short reaction times,
solvent-free nature of the reaction conditions, use of inexpensive and stable reagents, use of relatively small amounts
of the reagents and easy work-up procedure are worthy advantages of the present method.
Acknowledgment
We are thankful to the University of Guilan Research Council for the partial support of this work.
References
[
[
[
[
[
[
[
[
[
1] T.W. Greene, P.G.M. Wuts, Protective Groups in Organic Synthesis, 2nd ed., Wiley, New York, 1991.
2] K. Fuji, K. Ichikawa, E. Fujita, Tetrahedron Lett. 19 (1978) 3561.
3] D.W. Emerson, H. Wynberg, Tetrahedron Lett. 12 (1971) 3445.
4] T. Ravindranathan, S.P. Chavan, S.W. Dantale, Tetrahedron Lett. 36 (1995) 2285.
5] T. Ravindranathan, S.P. Chavan, P.J. Vargese, et al. J. Chem. Soc., Chem. Commun. (1994) 1937.
6] T. Ravindranathan, S.P. Chavan, M.M. Awachat, Tetrahedron Lett. 35 (1994) 8835.
7] E.L. Eliel, K. Soai, Tetrahedron Lett. 21 (1981) 2859.
8] K. Nishide, K. Yokota, D. Nakamura, et al. Heterocycles 44 (1997) 393.
9] B. Karimi, H. Seradj, M.H. Taebi, Synlett (2000) 1798.
[
[
[
[
[
[
[
10] S.P. Chavan, P. Soni, S.K. Kamat, Synlett (2001) 1251.
11] F. Shirini, M. Abedini, M. Ghasemi, et al. Bull. Korean Chem. Soc. 10 (2009) 2479.
12] Fluka Catalogue, Handbook of Fine Chemicals, 1997–1998.
13] F. Shirini, M.A. Zolfigol, A.R. Abri, ARKIVOC II (2008) 14.
14] F. Shirini, M.A. Zolfigol, M. Abedini, Scientia Iranica 15 (2008) 440.
15] F. Shirini, M.A. Zolfigol, A.R. Abri, Chin. Chem. Lett. 19 (2008) 51.
16] F. Shirini, H. Tajik, A. Aliakbar, et al. Synth. Commun. 31 (2001) 767.