Chemistry Reference
In-Depth Information
enamine. Some of the artificial enzymes also catalyzed the condensation of
58
with
cyclopentanone. In this series we are using the catalytic groups on the cyclodextrin not
just to perform acid-base processes but also to bind an external ketone as its enamine
and thus promote intracomplex reactions.
1.4
Cytochrome P-450 Mimics
Enzymes exhibit wonderful selectivities, directed by the geometries of the enzyme--
substrate complexes. For many practical purposes, learning how to imitate such se-
lectivities is evenmore important than achieving rate accelerations at the enzyme level.
Of course, selectivity is a reflection of relative rates, but a selective rate advantage of
only one-hundred-fold could be enough to produce one product rather than either
another or a mixture. This is easier to achieve than the huge overall rate accelerations
that most enzymes exhibit.
1.4.1
Aromatic Substitution in Cyclodextrin Complexes
In one of our earliest approaches to such biomimetic selectivity, directed by the geo-
metry of the catalyst-substrate complex, we examined the directed substitution of an
aromatic ring bound into the cyclodextrin cavity [142, 143]. Anisole was chlorinated by
HOCl entirely in the para position when it was bound into
a
-cyclodextrin, while in
