Regeneration of carbonyl compounds from oximes under microwave irradiation in solventless system

Article abstract of DOI:10.1515/znb-2000-0513

A new, mild, efficient and environmentally benign method for the cleavage of oximes has been achieved by a simple reaction of oximes with wet alumina supported chromium(VI) oxide under microwave irradiations in solvent-free condition.

Full text of DOI:10.1515/znb-2000-0513

Regeneration of Carbonyl Compounds from Oximes under Microwave
Irradiation in Solventless System
Majid M. Heravia,Dariush Ajam ib, Rahim H ekm atshoar3, Yahya Sh. Beheshtiha3,
Karim Assadollah3, and Mitra Ghassemzadehb
a Departm ent of Chemistry, School of Sciences, Azzahra University, Vanak, Tehran, Iran
b Chemistry & Chemical Engineering Research Center of Iran, R O.Box 14335-186,
Tehran, Iran
Reprint requests Prof. Dr. M. M. Heravi. E-mail: mmheravi@azzahra.ac.ir
Z. Naturforsch. 55b, 43 1 -4 3 3 (2000); received D ecem ber 20, 1999
Oximes, Deoxim ations, Carbonyl Compounds
A
new, mild, efficient and environm entally benign method for the cleavage of oxim es has
been achieved by a simple reaction of oxim es with wet alumina supported chrom ium (VI)
oxide under microwave irradiations in solvent-free condition.
Introduction
protection of trimethylsilyl and tetrahydropyranyl
ethers [11]. Arm ed with these experiences and
considering the salient features of solvent free re­
action under microwave irradiations [12] we at­
temped the oxidative deoximation with supported
chromium(VI) oxide under these condition.
Among various mineral supports used such as
silica, clay, and alumina, alumina was found to give
the best results. Surprisingly moistening of the alu­
mina improved the yield drastically. The reaction
is conducted by mixing finely ground wet alumina­
chromiun(VI) oxide with neat oximes. We discov­
ered that in the absence of alumina the reactions
do not proceed and in the presence of dry alumina
Oximes are one of the most useful employed
protecting groups [1] and are extensively used for
purification of carbonyl compounds. Their synthe­
sis from non­carbonyl compounds [2] provides an
alternative pathway to aldehydes and ketones.
The im portant role of oximes as protecting
group has inspired the developm ent of several
deoximation reagents [3] including ammonium
persulfate­silica gel [4] supported sodium perio­
date [5], bismuth trichloride [6], Dess­M artin peri­
odenane [7] and tributylammonium peroxydisul­
fate [8]. Each of these reagents has its merit and
drawbacks. The importance of regeneration of car­
bonyl compounds from oximes assumed added af­
ter the discovery of the Barton reaction [9] in
which oximes are produced at non­activated hy­
drocarbon sites.
In continuation of our investigation on organic
manipulations in solventless system [10] we wish
to report a solid state deoximation m ethod using
wet alumina supported chrom ium (VI) oxide. A l­
though chromium (VI) oxide has been extensively
used for oxidative purposes to the best of our
knowledge its use in oxidative deoximation has
not been reported.
the reactions are sluggish and
a considerable
amounts of oximes are recovered unchanged at el­
evated tem perature or on exposure to microwave
irradiation for an extented period of time. By
using wet alumina­chromium(VI) oxide in all
cases the reactions are com pleted by simple mix­
ing and exposure to microwave irradiation. The
reactions are relatively clean with no tar formation
typical of some C r0 3 oxidations.
The irradiation of ketoximes with this reagent
afforded carbonyl compounds and did not result
in the formation of Beckmann rearranged pro­
ducts [13]. The optimum ratio of the substrate to
the reagent for cleavage of oximes was found to
be 1:3 (mole/ mole). The reactions rem ained in­
Results and Discussion
We have recently reported the use of wet alu­ complete when lower amounts of oxidant were
mina supported chrom ium (VI) oxide as a mild, ef­ used. Using conventional heating (oil bath) at
ficient and inexpensive reagent for oxidative de­ 100 °C the reaction can be completed in 24 hours.
0
932­0776/2000/0500­0431 $06.00 © 2000 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
D
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 7/15/15 8:32 AM

4
32
M. M. Heravi et al. ■Regeneration of Carbonyl Compounds from Oximes
Interestingly in these reactions no overoxidation
to carboxylic acids was observed.
Table. Solid state deoxim ation using wet alum ina-C r03
under microwave irradiation.
Substrate
Carbonyl compound
Reaction
time (sec.)
Yield
(%)
To assess the generality of m ethod several ox­
imes were oxidatively deoximated by this method
(
Table).
1
lP H
4
4
4
0
0
0
90
85
.
j y
Experimental
2
NOH
All compounds employed are known and were
identified by comparison of their physical data
with those of authentic samples. Yields refer to
isolated products.
x r
x f
3
Cl
NOH
Cl
0
83
82
85
Wet Alum ina supported chrom ium (VI) oxide
cy
Neutral aluminum oxide (10 g, Aldrich, Brock­
m ann 1­150 mesh) was shaken with destilled water
(
(
4
NOH
2 ml). This mixture (2.4 g) was mixed with C r0 3
0.8 g, 8 mmol) using a pastle and mortar.
40
Cr 1' Cr
1
5
NOH
Oxidative deoximation. General procedure
40
40
40
In a beaker, neat oxime (1 mmol) was mixed
thoroughly with the above catalyst (3 mmol) using
a spatula. The beaker was placed in a household
microwave oven and kept at 900 Watt for the spec­
ified time. A fter the completion of the reaction
jO A JO*'
6
NOH
84
82
(
confirmed by TLC, hexane:EtOAc 8:2) the pro­
o 1^
duct was extracted to CH 2C12 (2x20 ml) and
passed through a small bed of alumina (1 cm) to
afford the corresponding carbonyl compound (Ta­
ble).
7
NOH
„ i/ o «xAo
a) All substrates were synthesized by known literature
procedure.
A cknow ledgem ent
b) All products were characterized by comparison of
The financial support for this research from the
research council of Azzahra University is grate­
fully acknowledged.
their mp., IR and
thentic sample.
N M R spectra with those of an au-
c) Yields refer to isolated products.
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 7/15/15 8:32 AM

M. M. Heravi et al. ■R egeneration of Carbonyl Compounds from Oximes
433
[
1] T. W. Green, R G. M. Wuts, Protective Groups in
Organic Synthesis 1991, 2nd ed., p. 214, Wiley, New
York (1991) and references cited therein.
[8] O. Yan, M. Liu, D. Zhang, L. Shao, Synth. Commun.
29 1049(1999).
[9] D. H. R. Barton, J. M. Beaton, L. E. Geller, M. M.
Pechell, J. Am. Chem. Soc. 83, 4076, 4083, (1961).
[10] a) M. M. Heravi, R. Kiakojoori, K. Tabar­Hydar, J.
Chem. Res. 656(1998);
[2] G. W. Kabalka, R. D. Race, R P. Wadgaonkar,
Synth. Commun. 10, 2453 (1990).
[3] a) D. P. Curran, J. F. Brill, D. M. Rakowicz, J. Org.
Chem. 49, 1694 (1984);
b) C. G. Rao, A. S. Radhakrishna, B. B. Singh, S. P.
Bhalnagar, Synthesis 808 (1983);
b) M. M. Heravi, D. Ajami, Monatsh. Chem. 130,
709(1999);
c) M. M. Heravi, D. Ajami, M. M. Mojtahedi, M.
Ghassemzadeh, Tetrahedron Lett. 40, 561 (1999);
d) M. M. Heravi, D. Ajami, M. Ghassemzadeh,
Synth. Commun. 29, 1013 (1999);
e) M. M. Heravi, D. Ajami, K. Aghapoor, M. Ghas­
semzadeh, J. Chem. Soc., Chem. Commun. 833
(1999);
c) S. B. Skim, K. Kim, Y. H. Kim, Tetrahedron Lett.
2
8, 645 (1987);
d) J. R. Meloney, R. E. Lyle, J. E. Saavedra, G. G.
Lyle, Synthesis 212(1978);
e) O. A. Olah, O. Liao, C. S. Lee, G. K. Surya Pra­
kash, Synlett 427(1993);
f) R. Josef, A. Sudalai, T. Ravendranathan, Tetrahe­
f) M. M. Heravi, D. Ajami, M. Ghassemzadeh, K.
Tabar­Hydar, J. Chem. Res. 334 (1999).
[11] a) M. M. Heravi, D. Ajami, K. Tabar­Hydar, Mo­
natsh. Chem. 130, 337 (1999),
b) M. M. Heravi, D. Ajami, M. Ghassemzadeh, Syn­
thesis 393 (1999).
[12] a) A. Oussaid, L. N. Thach, A. Loupy, Tetrahedron
Lett. 38, 2451 (1997),
b) R. S. Varma, R. Dahiya, Tetrahedron Lett. 38,
2043 (1997).
[13] A. Z. Busch, P. Cruz, E. Diez­Barra, A. Loupy, F.
Langa, Synlett 1259 (1995).
dron Lett. 35, 5493(1994);
g) M. Curini, O. Rosati, E. Pisani, Synlett 333(1996);
h) B. Bandgar, L. Kunde, J. Thote, Synth. Commun.
2
7, 1149(1997).
4] S. Varma, H. M. Meshram, Tetrahedron Lett. 38,
427(1997).
5] S. Varma, R. Dahuya, R. K. Saini, Tetrahedron Lett.
8, 8819(1997).
6] A. Boruah, B. Baruah, D. Prajapati, J. S. Sandhu,
Tetrahedron Lett. 38, 4267(1997)
7] D. S. Bose, A. V. Narsaiah, Synth. Commun. 29,
37(1999).
[
5
[
3
[
[
9
Brought to you by | New York University Bobst Library Technical Services
Authenticated
Download Date | 7/15/15 8:32 AM