Activation of DMSO by phosphonitrilic chloride: An efficient method for oxidation of alcohols

Article abstract of DOI:10.1080/00397910701572597

A variety of alcohols have been oxidized under mild conditions by a dimethylsulfoxide (DMSO)-chlorophosphazene complex. Sensitive groups such as silyl and tetrahydropyranyl (THP) ethers are stable under this condition. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910701572597

This article was downloaded by: [Brown University]
On: 04 May 2013, At: 14:29
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
Activation of DMSO by Phosphonitrilic
Chloride: An Efficient Method for Oxidation
of Alcohols
Sanjay K. Pandey a , Alakesh Bisai a & Vinod K. Singh a
a Department of Chemistry, Indian Institute of Technology, Kanpur, India
Published online: 10 Dec 2007.
To cite this article: Sanjay K. Pandey , Alakesh Bisai & Vinod K. Singh (2007): Activation of DMSO by
Phosphonitrilic Chloride: An Efficient Method for Oxidation of Alcohols, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 37:23, 4099-4103
To link to this article: http://dx.doi.org/10.1080/00397910701572597
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
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.
The publisher does not give any warranty express or implied or make any representation that the
contents will be complete or accurate or up to date. The accuracy of any instructions, formulae,
and drug doses should be independently verified with primary sources. The publisher shall not
be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or
howsoever caused arising directly or indirectly in connection with or arising out of the use of this
material.

Synthetic Communicationsw, 37: 4099–4103, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701572597
Activation of DMSO by Phosphonitrilic
Chloride: An Efficient Method for Oxidation
of Alcohols
Sanjay K. Pandey, Alakesh Bisai, and Vinod K. Singh
Department of Chemistry, Indian Institute of Technology, Kanpur, India
Abstract: A variety of alcohols have been oxidized under mild conditions by a
dimethylsulfoxide (DMSO)–chlorophosphazene complex. Sensitive groups such as
silyl and tetrahydropyranyl (THP) ethers are stable under this condition.
Keywords: dimethylsulfoxide, phosphonitrilic, swern oxidation
The oxidation of alcohols to the corresponding carbonyl compounds is a very
important and frequently used transformation in organic synthesis.[1] One of
the most common methods for oxidation is via activated DMSO (Swern
oxidation),[2,3] which involved a variety of electrophilic reagents as activators
such as oxalyl chloride,[4] acid anhydrides,[5] phosgene,[6] bis(trichloro-
methyl)carbonate,[7] cyanuric chloride,[8] and others.[9,10] The reaction
proceeds via an alkoxysulfonium salt that reacts with a base to give a
carbonyl compound and dimethyl sulfide. The major disadvantage of the
reaction is the formation of methylthioalkyl ether as a by-product, due to
Pummerer rearrangement of the alkoxysulfonium ylide. Among all the activa-
tors, oxalyl chloride and triphenylphosphine dihalide gave the highest yield of
carbonyl compounds with minimal or no Pummerer product. Although
DMSO–oxalyl chloride is routinely used for the oxidation, the method is
still associated with some disadvantages such as violent reaction during the
Received May 3, 2007
Address correspondence to Vinod K. Singh, Department of Chemistry, Indian
Institute of Technology, Kanpur 208 016, India. E-mail: vinodks@iitk.ac.in
4099

4100
S. K. Pandey, A. Bisai, and V. K. Singh
formation of ylide and toxicity associated with vapors of the latter. While
working on the reaction of activated DMSO with epoxides and other
strained rings,[10,11] we discovered that phosphonitrilic chloride in combi-
nation with DMSO is a good alternative for classical Swern oxidation.
Details of the work are described in this article.
At the outset, a simple primary alcohol was treated with a reagent
prepared from DMSO and phosphonitrilic chloride in CH2Cl2 at 2408C
followed by Et3N under the conditions of Swern oxidation. The ketone was
thus obtained in 84% isolated yield (entry 1). To show the scope of the
reaction, a variety of alcohols were oxidized with these reagents, and the
results are summarized in Table 1. All kinds of alcohols, such as primary,
secondary, allylic, and benzylic alcohols, could be oxidized to carbonyl
compounds in high yields. The worthy feature of the reaction was that an
alcohol that has a sulfur atom in the molecule could also be oxidized in
excellent yield (entry 11). The oxidation could also be carried out in a
molecule that has silyl ethers, which were inert to these conditions (entries
16, 17, 20, and 21). The THP ether is stable under the conditions used for
the oxidation reaction (entry 19). Oxidation of a sensitive substrate such as
geraniol was very smooth, giving an aldehyde in high yield (entry 15). The
oxidation of geraniol proceeded efficiently (87% yield) even with use of 0.5
equivalent of phosphonitrilic chloride. However, on the use of 0.33 equivalent
of the reagent, the yield dropped down to 60%. The yield increased to 95% if
the reaction was done at 2788C using 1 equivalent of the reagent. There was
no epimerization under these reaction conditions (entry 21).
In conclusion, we have described a mild method for oxidation of alcohols
using DMSO–phosphonitrilic chloride. Some functional groups, which
otherwise would have reacted with these reagents, remained unaffected
under the reaction conditions.
GENERAL PROCEDURE
DMSO (4 mmol) was added to a solution of phosphonitrilic chloride
(1.0 mmol) in CH2Cl2 (5 mL) at 2408C. The color of the solution turned
milky white. After 1 h, 1 equivalent of an alcohol solution in CH2Cl2
(2 mL) was added, and the reaction mixture was stirred at the same tempera-
ture for 45 min, when Et3N (5 mmol) was added. The reaction mixture was
slowly allowed to come to rt (8 h). The reaction mixture was taken in
CH2Cl2 and washed with water and brine. The organic layer was dried over
Na2SO4 and condensed. The crude product was chromatographed over
silica gel by column chromatography to provide pure ketones in high yields
(Table 1). All the carbonyl compounds are either commercially available or
known in literature. They were characterized by the usual spectral data and
compared with authentic samples.

Activation of DMSO
4101
Table 1. Oxidation of alcohols to ketones
Isolated yield
(%)
S. no.
Substrate
Product
1
2
84
67
3
59
4
5
97
94
6
7
93
96
8
82
9
79
79
10
11
12
93
96
13
14
Cyclododecanol
Cyclododecanone
86
91
4-t-butyl cyclohexanol
4-t-butyl cyclohexanone
(continued)

4102
S. K. Pandey, A. Bisai, and V. K. Singh
Table 1. Continued
Isolated yield
(%)
S. no.
15
Substrate
Product
90
16
17
18
19
20
21
90
88
93
77
62
82
ACKNOWLEDGMENT
We thank the Council of Scientific and Industrial Research (CSIR) (govern-
ment of India) for funding our research.
REFERENCES
1. For a review, see Haines, A. H. In Methods for the Oxidation of Organic
Compounds; Academic Press: New York, 1988.
2. For reviews on Swern oxidation, see (a) Mancuso, A. J.; Swern, D. Synthesis 1981,
165; (b) Tidwell, T. T. Org. React. 1990, 39, 297.
3. For comparative study, see Omura, K.; Swern, D. Tetrahedron 1978, 34, 1651.
4. (a) Mancuso, A. J.; Huang, S. L.; Swern, D. J. Org. Chem. 1978, 43, 2480;
(b) Singaram, B.; Chrisman, W. Tetrahedron Lett. 1997, 38, 2053.
5. (a) Omura, K.; Sharma, A. K.; Swern, D. J. Org. Chem. 1976, 41, 957;
(b) Amon, C. M.; Banwell, M. G.; Gravatt, G. L. J. Org. Chem. 1987, 52, 4851;
(c) Kawada, K.; Gross, R. S.; Watt, D. S. Synth. Commun. 1989, 19, 777.
6. (a) Barton, D. H. R.; Garner, B. J.; Wightman, R. H. J. Chem. Soc. 1964, 1855;
(b) Takano, S.; Inomata, K.; Tomita, S.; Yanase, M.; Samizu, K.;
Ogasawara, K. Tetrahedron Lett. 1988, 29, 6619.
7. Palomo, C.; Cossio, F. P.; Ontoria, J. M.; Odriozola, J. M. J. Org. Chem. 1991, 56,
5948.

Activation of DMSO
4103
8. De Luca, L.; Giacomelli, G.; Porcheddu, A. J. Org. Chem. 2001, 66, 7907.
9. For other related methods, see (a) Corey, E. J.; Kim, C. U.; Takeda, M. Tetra-
hedron Lett. 1972, 4339; (b) Taber, D. F.; Amedio, J. C., Jr.; Jung, K.-Y.
J. Org. Chem. 1987, 52, 5621.
10. For a recent paper on the use of DMSO-Ph3P.X2, see Bisai, A.; Chandrasekhar, M.;
Singh, V. K. Tetrahedron Lett. 2002, 43, 8355.
11. (a) Raina, S.; Bhuniya, D.; Singh, V. K. Tetrahedron Lett. 1992, 33, 6021;
(b) Raina, S.; Singh, V. K. Tetrahedron 1995, 51, 2467.