N-Bromobis(p-toluenesulfonyl)amine as a novel and mild reagent for conversion of oximes to carbonyl compound

Article abstract of DOI:10.1080/10426500490459786

N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient reagent for the conversion of oximes to their corresponding carbonyl compounds in good yields under mild conditions.

Full text of DOI:10.1080/10426500490459786

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Phosphorus, Sulfur, and Silicon and the Related
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N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS A NOVEL
AND MILD REAGENT FOR CONVERSION OF OXIMES TO
CARBONYL COMPOUND
Ramin Ghorbani-Vaghei a & Ardeshir Khazaei a
a Bu-Ali Sina University , Hamadan, Iran
Published online: 16 Aug 2010.
To cite this article: Ramin Ghorbani-Vaghei & Ardeshir Khazaei (2004) N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS A NOVEL
AND MILD REAGENT FOR CONVERSION OF OXIMES TO CARBONYL COMPOUND, Phosphorus, Sulfur, and Silicon and the Related
Elements, 179:6, 1169-1173, DOI: 10.1080/10426500490459786
To link to this article: http://dx.doi.org/10.1080/10426500490459786
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Phosphorus, Sulfur, and Silicon, 179:1169–1173, 2004
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Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490459786
N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS
A NOVEL AND MILD REAGENT FOR CONVERSION
OF OXIMES TO CARBONYL COMPOUND
Ramin Ghorbani-Vaghei and Ardeshir Khazaei
Bu-Ali Sina University, Hamadan, Iran
(Received October 14, 2003; accepted October 16, 2003)
N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient
reagent for the conversion of oximes to their corresponding carbonyl
compounds in good yields under mild conditions.
Keywords: Carbonyl compounds; deprotection; NBBTA; oximes
Regeneration of carbonyl compounds from their oximes is an important
reaction because oxime serves as an efficient protective group for alde-
hydes and ketones, and these are used extensively for the purification of
carbonyl compounds. A number of methods have been reported for the
transformation of oximes to the corresponding carbonyl compounds,1−16
and newer methods are continuously added. Some of these methods re-
quire the use of strong bases, acids or oxidizing agents, i.e., conditions
that may be incompatible with sensitive substrate molecules and may
thus lead to the formation of side products. Further these methods have
drawbacks such as the use of expensive or less easily available reagents,
vigorous reaction conditions, prolonged standing and high temperature,
complicated reaction procedures, and tedious work-up in the isolation
of pure products. Some of them are corrosive, toxic, and have low yields.
RESULTS AND DISCUSSION
We now report a convenient method for the deoximation of ketone and
aldehyde oximes to their corresponding carbonyl compounds using a
new reagent (NBBTA) 2 that is prepared from p-toluenesulfonyl chlo-
ride (Scheme 1).
Address correspondence to Ramin Ghorbani-Vaghei, Department of Chemistry, Fac-
ulty of Science, Bu-Ali Sina University, Hamadan, Iran. E-mail:ghorbani@basu.ac.ir
1169

1170
R. Ghorbani-Vaghei and A. Khazaei
SCHEME 1
The advantages of NBBTA are as follows:
1. The preparation of N-bromobis(p-toluenesulfonyl)amine is easy.
2. NBBTA is stable for a long time in atmospheric condition.
3. After reaction of NBBTA with substrate, the sulphonamide is recov-
ered and can be reused many times without decreasing the yield.
4. NBBTA is regarded as pure.
The reaction of oximes (3) with NBBTA in CCl4 afforded carbonyl
compounds (4) without side products (Scheme 2).
SCHEME 2
We suggest the following mechanism for the conversion (Scheme 3).
The results of the conversion of various ketoximes and aldoximes to
ketones and aldehydes are presented in Table I. The products of the
reaction with NBBTA were isolated simply by filtering of 1 and evapo-
rating the solvent from the filtrate. The method has advantage in terms
of yields, simplicity of reaction conditions, short reaction times and no

Deoximation
1171
TABLE I Oxidative Cleavage of Oximes with NBBTA
Reaction
times (h)
Entry
R1
R2
Producta
Acetophenone
p-Methoxyacetophenone
Benzophenone
p-Chlorobenzophenone
Benzaldehyde
o-Chlorobenzaldehyde
o-Hydroxybenzaldehyde
p-Chlorobenzaldehyde
Benzoin
Yield (%)
1
2
3
4
5
6
7
8
9
CH3
CH3
C6H5
C6H5
H
H
H
H
C6H5
2.5
2.0
2.0
2.0
2.5
2.0
2.5
2.0
3.0
3.5
4.0
3.0
93
91
95
90
92
90
91
90
91
89
91
92
p-MeOC6H5
C6H5
p-ClC6H5
C6H5
o-ClC6H5
o-OHC6H5
p-ClC6H5
C6H5CH(OH)
C2H5
C6H5
C6H5
CH3
10
11
12
Propiophenone
2-Octanone
Cyclohexanone
C6H13
aProducts were characterized by their physical constants, comparison with
authentic samples, and IR spectra.
SCHEME 3

1172
R. Ghorbani-Vaghei and A. Khazaei
side products. The recovered starting material (1), was rebrominated
and used many times without reducing the yield.
CONCLUSIONS
From the results obtained, we find that the described procedure and
the reaction conditions are simple. NBBTA is stable and the recovered
regent can be reused.
EXPERIMENTAL
General
The oximes were prepared by a standard procedure. Commercial p-
toluenesulfonyl chloride was used as received. p-Toluenesulfonylamine
was prepared according to the literature. The purity of the compounds
was checked by TLC.
Procedure for the Preparation of
N-Bromobis(p-toluenesulfonyl)amine
Bis (p-toluenesulfonyl)amine (10 g, 0.06 mmol) was dissolved in a slight
molar excess of chilled sodium hydroxide solution (3 M) at room tem-
perature and was transfered to a beaker. 3 ml of bromine dissolved in
15 ml of carbon tetrachloride were added to the solution with vigorous
stirring and immediately a yellow precipitate was formed. The prod-
uct (yellow precipitate) was collected on a Bu¨chner funnel and it was
washed with 30 ml of distilled cold water and then dried in a vacuum
dessicator at room temperature for 6 h. The reaction gives the prod-
uct in 9 g (90%) yield. Melting point was 103–106◦C. IR (KBr): ν 1600,
1470, 1340, 1150 cm−1. 1H NMR (acetone-d6): δ 2.42 (s, 6H), 7.50–7.76
(dd, 8H). 13C NMR (acetone-d6): δ 20.15 (CH3), 126.13–141.21 (benzene
carbons).
General Procedure for Deoximation with
N-Bromobis(p-toluenesulfonyl)amine
A mixture of oxime (5 mmol), carbon tetrachloride (10 ml), and N-
bromobis(p-toluenesulfonyl)amine 2 was stirred at room temperature
for the specified time (Table I). The reaction was monitored by TLC.
After completion of the reaction, water was added to hydrolyze the in-
termediate, and the insoluble sulfonamide 1 was removed by filteration

Deoximation
1173
and washed with cold carbon tetrachloride (5 ml). Removal of the sol-
vent under reduced pressure gave the crude product. Solid products
were recrystallized from diethyl ether, oily products were dissolved in
ether and the ether solution washed, dried, and concentrated.
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