Jasmone 1 - ChemistforChrist

Synthesis of JASMONE
O
O
DIBAL-H
For a lactone the best
reducing agent to a lactole
is DIBAL-H, for an ester this
might not work so well!
H
OH
O
Thermodynamically more
stable due to being
a trisubstituted double
bond.
O
under the acidc
conditions:
isomerization
MeLi
Me
Jasmone
O
O
OH
More resources available at
www.chemistforchrist.de
OH
O
CrO 3, verd. H 2SO 4, Aceton
Jones-Reagent
Me CrO3, verd. H2SO4, Aceton
OH
Jones-Reagent
CrO 3
HO
tertiary alcohol,
H 2O is eliminated
Wittig
tertiary alcohol cannot be oxidized!
The textbook Clayden, Greeves, Warren and Wothers (Oxford University press, p. 951, 2004 reprint) proposes
a different mechanism:
OH (VI)
OH
O
R Li
R
O
CrO3 R (VI)
CrO
orange
3
OH
R CrO 3
H
O OH
Cr
O O
R
H
[3,3]
HO OH
Cr
O O
H
H R
Me
O
(III)
CrO3 R
+ Cr(IV)
green
PPh 3
OH
Me
Me
gives Cr(III) and Cr(VI)
by disproportionation.
The first step is the formation of a chromate ester but this intermediate has no proton to lose, so it transfers
the chromate to the other end of the allylic system where there is a proton. The chromate transfer can be
drawn as a [3,3] sigmatropic rearrangement.
Very general method:
R' MgBr
O
R
HO
R'
R'
R H
R
OH
Ox
R'
R
O