1) Compounds with a β-hydrogen react by β elimination preferentially.
- A variety of cyclopropane derivatives has been prepared by generating
dichlorocarbene in the presence of alknenes.
2) Compounds with no β-hydrogen but with an α-hydrogen react by α
elimination.
H
KOC(CH) Cl
H
Cl
3 3
CHCl
7,7-Dichlorobicyclo[4,1,0]heptane
(59%
8.9C CARBENOIDS: THE SIMMONS MITH CYCLOPROPANE SYNTHESIS
- H. E. Simmons and R. D. Sm the DuPont Company had developed a useful
cyclopropane synthesis by reacting a zinc-copper couple with an alkene.
- The diiodomethane and zinc react to produce a carbene-like species called a
carbenoid.
3
)
ith of
-S
CH 2 I 2 + Zn(Cu) ICH 2 ZnI
A carbeniod
fic addition of a CH 2 group
directly to the double bond.
8.10 OXIDATION OF ALKENES: SYN-HYDROXYLATION
2) The carbenoid then brings about the stereospeci
- Potassium permanganate or osmium tetroxide oxidize alkenes to furnish 1,2-diols
(glycols).
