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

Synthesis of β-Vetivone
Synthesis of the starting material:
O
5
Synthesis:
H
H
1
O
O
Rationale:
Pseudo 1,3 diaxial interaction
O
O O (Enolate of acetaldehye is very
difficult to create, either the use
of enamine chemistry or reacting
n-BuLi with THF might help).
O
n-BuLi
O
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Li
+
OLi
This is the reason why reactions including THF and n-BuLi
are often cooled down to -78°C.
O
O O
favored
(2 methyl are eq, ax)
+
disfavored
(2 methyl are ax, ax)
O
Ozonolysis + work up with
Me 2S
O
Me 2CuLi
O
1 single
diasteroisomer
is formed
The hydrogenation of only on of the double bonds in the furane ring proofed to be very difficult. The only
reagent found to do the job was Diimine:
Reminder of diimine reduction
Usually gives an excellent Z/E ration (up to 99.9%)
Synthesis of H N N H :
DEAD:
EtO2C N N CO2Et H 2O / NaOH
Na O2C N N CO2 Na
Very reactive! H N N H
HO2C N N CO
- CO
2H
2
Problem: Intermediates and the diimine might be explosive (Not done in industry, largest scale might be 2 or 3
mmol).
H
OH