Synthesis of β-Vetivone More resources available ... - ChemistforChrist

Synthesis of β-Vetivone
Enolate can only
be formed here
O
O
This bond is the precursor
of the C=O bond
Methyl group is supposed to
direct the reactions to give
diasteromerically pure compounds.
Posner is using the same dihalide precursor as Storck (see above)
allylic bromide is
O
O
substituted faster
Br
KHMDS
Br
O
KHMDS
+
O
Mesitoylchloride
DMAP
Synthesis of Dauben
JACS 1975, 97, 1622
JACS 1977, 99, 7307
O
O
OH
O
Br
OH
1 eq.MeMgr
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O
Use of Mesitoylchloride prrevents the ketone from being attacked again by MeMgBr
to afford the corresponding tert-alcohol.
O
CrO 3 . 2Pyr
Ph 3P CH 2
Using the Fuchs (from Corey-Fuchs reaction) Synthon:
O
OH
Br
CH 2 O
O
1. CrO 3
2. SnCl 4
Oxidation to
aldehyde and
cyclisation
(no standard
chemistry)
O
O
K
O
O
LiAlH 4
PPh3 BF4
CO2Et - -
The Counterion BF4 is chosen because Cl and other halides often give very hygroscopic Salts and are often less
soluble.
CH 2
OH