Page 529 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

510 It has been suggested that the TS for DMDO oxidation of electron-poor alkenes, such
as acrylonitrile, has a dominant nucleophilic component. 147 DMDO oxidations have
CHAPTER 5 a fairly high sensitivity to steric effect. The Z-isomers of alkenes are usually more
Polar Addition reactive than the E-isomers because in the former case the reagent can avoid the alkyl
and Elimination 148
Reactions groups. We say more about this in Section 5.8.

Z-3-hexene E-3-hexene Z-2,5-dimethyl E-2,5-dimethyl
-3-hexene -3-hexene
rate ratio: 8.3:1
rate ratio: 17:1
Similarly to peroxycarboxylic acids, DMDO is subject to cis or syn stereose-
lectivity by hydroxy and other hydrogen-bonding functional groups. 149 The effect is
strongest in nonpolar solvents. For other substituents, both steric and polar factors seem
to have an influence, and several complex reactants have shown good stereoselectivity,
although the precise origin of the stereoselectivity is not always evident. 150
Other ketones apart from acetone can be used for in situ generation of dioxi-
ranes by reaction with peroxysulfate or another suitable peroxide. More electrophilic
ketones give more reactive dioxiranes. 3-Methyl-3-trifluoromethyldioxirane is a more
reactive analog of DMDO. 151 This reagent, which can be generated in situ from
1,1,1-trifluoroacetone, is capable of oxidizing less reactive compounds such as methyl
cinnamate.

O
CF CCH 3
3
O
HOOSO K
3
PhCH CHCO CH 3 PhCH CHCO 2 CH 3
2
CH CN, H O
3
2
Ref. 152
Hexafluoroacetone and hydrogen peroxide in buffered aqueous solution epoxi-
dizes alkenes and allylic alcohols. 153 Other fluoroketones also function as epoxi-
dation catalysts. 154 155 N,N-dialkylpiperidin-4-one salts are also good catalysts for
147
D. V. Deubel, J. Org. Chem., 66, 3790 (2001).
148 A. L. Baumstark and C. J. McCloskey, Tetrahedron Lett., 28, 3311 (1987); A. L. Baumstark and
P. C. Vasquez, J. Org. Chem., 53, 3437 (1988).
149
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G. B. Carpenter, J. Org. Chem., 64, 4705 (1999).
150 R. C. Cambie, A. C. Grimsdale, P. S. Rutledge, M. F. Walker, and A. D. Woodgate, Austr. J. Chem.,
44, 1553 (1991); P. Boricelli and P. Lupattelli, J. Org. Chem., 59, 4304 (1994); R. Curci, A. Detomaso,
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151 R. Mello, M. Fiorentino, O. Sciacovelli, and R. Curci, J. Org. Chem., 53, 3890 (1988).
152
D. Yang, M.-K. Wong, and Y.-C. Yip, J. Org. Chem., 60, 3887 (1995).
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1274 (1999).
154 E. L. Grocock, B.A. Marples, and R. C. Toon, Tetrhahedron, 56, 989 (2000).
155
J. Legros, B. Crousse, J. Bourdon, D. Bonnet-Delpon, and J.-P. Begue, Tetrahedron Lett., 42, 4463
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