Jasmone 1 - ChemistforChrist

Synthesis of JASMONE
The Nazarow reaction: Short revision
For more details see: Org. React. 1994, 45, 1-158
O
O
R R
O
H
hν (254 nm)
benzene
AcOH, H 3PO 4
50°C
R R
Disrotatory Conrotatory
O
R R
R R
In its simplest form the Nazarow cyclization is the ring closure of a doubly α,β unsaturated ketone to give a
cyclopentenone.
O
H
R R
O
H
R R
R
empty
OH
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R
O
R R
array of five p orbitals
containing 4p electrons
One of the five π orbitals involved is empty, so the cyclization is a 4π electrocyclic reaction and the orbitals
forming the new σ bond must interact antarafacially.
H
O
OH
O
OH
OH
R R
R
π 4
a
R
H
R
R
R R
R R
cyclopentenone
Usually the double bond is formed at the site which is higher substituted (thermodynamically more stable
product) to get the double bond at the less substituted site can also be done by introducing a siliconsubstituent:
O
TMS R
Lewis acid
LA
O
TMS R
Nazarow
LA
O
TMS R
Anion
H 3O
O
R