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Novel aromatic deamination
18 April 2009 - News
The
David MacMillan
group recently came up with a way to remove an
amino
group from an
arene
. In this way the amine can direct an
electrophilic aromatic substitution
in a specific way and later on be discarded, very much like a
sulfonate group
(deactivating rather than activating). The strategy employed is
methylation
of the amine, followed by a
Birch reduction
and a kind of
vinylogous
Hofmann elimination
(
DOI
):
:
The novel procedure was demonstrated with a synthesis of
Tolterodine
:
as a sequence of an
asymmetric
Friedel-Crafts reaction
using
cinnamaldehyde
, an pyrrolidinoanisole and a
McMillan catalyst
, followed by a
reductive amination
(
diisopropylamine
,
sodium triacetoxyborohydride
), removal of the pyrrolidinone group by
methyl triflate
and
sodium
/
ammonia
treatment, followed by ether deprotection (
boron tribromide
) to the phenol.