Chapter 15: Alcohols, Diols and Thiols
Alkoxymercuration-Demercuration of Alkenes
(review of Chapter 14)
Reaction type: Electrophilic Addition
Summary
Overal transformation
C=C
to
H
-C-C-
OR
Typical reagents are mercury acetate, Hg(OAc)
2
in
ROH
/ THF
Unfortunatley, mercury compounds are generally quite toxic
Regioselectivity predicted by
Markovnikov's rule
The reaction is not stereoselective
Reaction proceeds via the formation of a cyclic
mercurinium ion
The mercurinium ion is opened by the attack of alcohol to complete the
alkoxymercuration.
When the alcohol attacks, it does so at the more highly substituted carbon.
Demercuration
is effected by a reduction using sodium borohydride,
NaBH
4
Questions
:
Are rearrangements a problem with this process ?
Why does the alcohol attack the more highly substituted carbon ?
Related reactions
Oxymercuration-demercuration of alkenes
(Ch 14)
