Page 1125 - Advanced Organic Chemistry Part B - Reactions & Synthesis

reactivity of the ketone toward nucleophilic addition and also makes the dioxirane 1101
intermediate more reactive.
SECTION 12.2
C H
12 25
Addition of Oxygen at
N + O Carbon-Carbon Double
Bonds
CH 3 O
PhCH CHCH OH
2
KOSO OOH PhCH CHCH OH
2
2
83%
The cyclic sulfone 4-thiopyrone-S S-dioxide also exhibits enhanced reactivity as a
result of the effect of the sulfone dipole. 103
Scheme 12.12 gives some examples of epoxidations involving dioxiranes. Entry 1
indicates the ability of the reagent to expoxidize deactivated double bonds. Entry 2
Scheme 12.12. Epoxidation by Dioxiranes

O O
1 a
DMDO O
CH CH 3 CH 3 CH 3
3
CH 3 CH 3 86%
C H
12 25
2 b +
N O
CH 3 O
KOSO OOH 87%
2
3 c
PhCH OCH 2 PhCH OCH
2
O 2 2 O
DMDO
PhCH O PhCH O O 99% yield, 20:1 α:B
2
2
OCH Ph OCH Ph
2
2
4 d OCH 3 OCH 3
CH 3 CH 3
DMDO
CH O C CH 3 CH O C CH 3 O 99%
2
3
2
3
5 e O CPh O CPh
2
2
DMDO
CO CH 3 CO CH 82%
3
2
2
TBDMSO N TBDMSO N
O
CO CH Ph CO CH Ph
2
2
2
2
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1553 (1991).
e. T. C. Henninger, M. Sabat, and R. J. Sundberg, Tetrahedron, 52, 14403 (1996).
103
D. Yang, Y.-C. Yip, G.-S. Jiao, and M.-K. Wong, J. Org. Chem., 63, 8952 (1998).