Chemistry Reference
In-Depth Information
only with activated aromatics, e.g. anisole, mesit-
ylene, etc. [53] (Schemes 13.23 and 13.24).
Envirocat EPIC also proved to be highly active and
selective in an acylation of anisole to produce an
intermediate to the drug tamoxifen and its ana-
logues. In this example, the acylation is performed
using two equivalents of anisole. Complete acylation
is observed by GC over 14.5 h and an almost quan-
titative crude yield of the ketone is obtained with
>96% selectivity for the
para
isomer (see Scheme
13.25). In fact, the R&D team at CCL went on to
develop a novel laboratory process to produce the
intermediate shown in Scheme 13.26, which is two
steps away from tamoxifen or its analogues.
8.3 Envirocat EPZ10
This supported reagent can be used to replace mild
Lewis acid catalysts (e.g. ZnCl
2
). For example, tetra-
alkoxypropanes are agrochemical intermediates that
are formed via an addition reaction between a tri-
alkyl orthoformate and a vinyl ether. Traditionally,
this reaction is catalysed by homogeneous ZnCl
2
and,
although it is an efficient catalyst, it must be washed
from the reaction mixture before the product can be
isolated, resulting in toxic acidic waste. The team at
CCL developed a process that replaced homogeneous
ZnCl
2
with Envirocat EPZ10, which was translated
successfully to a pilot trial (see Scheme 13.27). Not
only was the aqueous waste normally associated
with this process eliminated, but also a second use
of the catalyst was achieved without loss of activity
or selectivity.
9 The Second Generation of Envirocats
NO
2
EPZG
100
o
C / 20min
PhCHO
+
CH
3
NO
2
It has been 10 years since Envirocats were launched
onto the market and during that time only Enviro-
cat EPZG currently is being used in a commercial
process. However, it must be remembered that Envi-
rocats represent a radical innovation in catalysis for
Ph
Yield = 94%
No Z-isomers detected
Scheme 13.22
O
OCH
3
COOH
+
EPIC
Reflux / 10min
Cl
Cl
OCH
3
Yield = 69%
Scheme 13.23
O
COOH
EPIC
+
165ºC / 6.5h
Cl
Conversion = 100%
Yield = 90%
Cl
Scheme 13.24
OCH
3
OCH
3
EPIC
Cl
Cycloh
exane
+
130-150
o
C / 14.5h
O
O
Scheme 13.25
