W. Chrisman et al. / Tetrahedron Letters 42 (2001) 4775–4777
4777
In a control experiment, 4-methyl-2-pentanone oxime
(1e) was stirred with dried alumina containing no per-
manganate under otherwise identical reaction condi-
tions to address the possibility that alumina-catalyzed
oxime hydrolysis might be occurring first, followed by
an oxidation of hydroxylamine. The oxime was recov-
ered unchanged (97% yield, 99.9% GC yield) indicating
that ASPP is oxidizing the oxime itself, and not hydroly-
sis products. Next, we observed the competitive oxida-
tion of cyclohexanone oxime in the presence of terminal
alkenes. When equimolar solutions of cyclohexanone
oxime and 1-hexene or 1-octene were treated with
ASPP in the presence of an internal standard, GC
analysis indicated that the oxime was exclusively oxi-
dized to ketone (Fig. 2).
Baruah, B.; Prajapati, D.; Sandhu, J. S. Tetrahedron Lett.
1997, 38, 4267; (g) Bose, D. S.; Srinivas, P. Synth. Com-
mun. 1997, 27, 3835; (h) Meshram, H. M.; Reddy, G. S.;
Srinivas, D.; Yadav, J. S. Synth. Commun. 1998, 28, 2593;
(i) Meshram, H. M.; Srinivas, D.; Reddy, G. S.; Yadav,
J. S. Synth. Commun. 1998, 28, 4401; (j) Shinada, T.;
Yoshihara, K. Tetrahedron Lett. 1995, 36, 6701.
7. (a) Solid Supports and Catalysis in Organic Synthesis;
Smith, K., Ed.; Prentice Hall: New York, 1992; (b)
Menger, F. M.; Lee, C. J. Org. Chem. 1979, 44, 3446.
8. (a) Noureldin, N. A.; Lee, D. G. Tetrahedron Lett. 1981,
22, 4889; (b) Noureldin, N. A.; Lee, D. G. J. Org. Chem.
1982, 47, 2790; (c) Noureldin, N. A.; Lee, D. G. Can. J.
Chem. 1984, 62, 2113; (d) Lee, D. G.; Chen, T.; Wang, Z.
J. Org. Chem. 1993, 58, 2918; (e) Zhao, D.; Lee, D. G.
Synthesis 1994, 915.
This method avoids the use of toxic reagents and an
aqueous work-up—both environmental liabilities on the
large scale. We hope this oxidative, non-aqueous
method for selective deoximation of ketoximes in the
presence of terminal alkenes will prove useful to
organic chemists.
9. Harris, C. E.; Chrisman, W.; Bickford, S. A.; Lee, L. E.;
Torreblanca, A. E.; Singaram, B. Tetrahedron Lett. 1997,
38, 981.
10. McBride, C. M.; Chrisman, W.; Harris, C. E.; Singaram,
B. Tetrahedron Lett. 1999, 40, 45–48.
11. A study in progress demonstrates that this reagent oxi-
dizes aldehydes to acids, so deoximation of aldoximes is
unlikely to be useful.
12. The reagent was still prepared from flame-dried alumina,
and stored in a desiccator. No water was added to this
reagent at any time.
Acknowledgements
The authors thank Ms. Lynnette Blaney for assistance
with this manuscript. This work was supported by the
Hewlett–Mellon Fund through Albion College, and by
an Albion College Faculty Start-up Grant.
13. To ensure that the MgSO4 itself had not absorbed the
oxime, 3 g MgSO4, 50 ml diethyl ether and 10 mmol
oxime were combined, stirred for 2 h, gravity filtered and
analyzed. No oxime loss was observed.
14. The importance of water content and solvent in alumina
supported permanganate reactions has been observed
before, though not for this reaction: See, Lee, D. G.;
Chen, T.; Wang, Z. J. Org. Chem. 1993, 58, 2918.
15. A representative procedure is as follows: alumina (neu-
tral, 150 mesh) is dehydrated by heating to 300°C while
stirring over a Bunsen burner for 15 minutes. After
cooling in a desiccator, the alumina is ground together
with potassium permanganate (1 mmol KMnO4/g
reagent) in a mortar and pestle until a homogeneous
purple powder is obtained. Next, 1e (2,5-dimethylcyclo-
hexanone oxime, 5 mmol) was dissolved in diethyl ether
(20 ml), cooled to 0°C, and alumina supported potassium
permanganate (6 mmol KMnO4, 6.0 g reagent) added in
four portions with vigorous stirring. After the first 1.5 g
portion was added, the mixture was allowed to stir for 5
minutes. Then, water (50 mmol, 0.9 ml) was added via
pipette. The purple reagent was consumed and the brown
color of MnO2 appeared. The next portion of reagent was
added when the KMnO4 was consumed. To test this, a
1–2 drop sample of the reaction mixture was placed on a
small piece of filter paper. If no purple color was
observed when the sample spot was treated with two
drops of water the next reagent portion was added. The
reaction was monitored by GC until the starting material
was consumed providing an 84% yield of ketone 2e.
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