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Venlafaxine via hetero-Diels-Alder
15 June 2008 - OrgChem
Mauro Panunzio is showcasing his azadiene
hetero-Diels-Alder protocol
with the synthesis of antidepressant
Venlafaxine
(
DOI
). Earlier in 2006 he target-practised on
Prozac
and
duloxetine
(
DOI
). Here is how it is done.
Benzaldehyde
(1) is added to
LiHMDS
to
imine
(2) which reacts as a
nucleophile
with
acid chloride
(3) in a
nucleophilic acyl substitution
to
azadiene
(4). HDA reaction of this intermediate with
cyclohexanone
is mediated by
Lewis acid
Eufod
and
microwave irradiation
to
lactam
(5).
Formaldehyde
adds a hydroxymethyl group and the
phenyl
group is removed in (6) with
formic acid
in a
transketalization
again using a microwave. In the final step
Lithium aluminium hydride
opens both
hemiaminal
groups to Venlafaxine (7).