Pericyclic reaction - the third type of organic
reaction mechanism along with ionic and radical
reactions - include some of the most powerful
synthetically useful reactions, like the Diels - Alder
reaction, 1,3- dipolar cycloadditions, the Alder ene
reaction, Claisen rearrangements, the 2,3-Wittig
rearrangement, diimide reduction, sulfoxide elimination
and many others. These reactions are characterised by
having cyclic transition structures, and also have
highly predictable stereochemical features. Every
organic chemist must be able to recognise the various
types of pericyclic reaction and know something of their
mechanisms and the factors that affect how well they
work in organic synthesis. This book identifies the four
main classes of pericyclic reaction, and discusses the
main characteristics of the most important class,
cycloadditions - providing a working knowledge, based on
real examples, of their scope, patterns of reactivity,
and stereochemistry. Then it explains the main features
using ideas based in molecular orbital theory, but ( as
in the companion book by A. J. Kirby on Stereoelectronic
Effects ) without mathematics.It presents the Woodward -
Hoffmann rules in the form of two all-encompassing
rules, one for thermal reactions and its opposite for
photochemical reactions. These rules are explained in
detail and carefully illustrated, so that you will be
able to predict the stereochemical outcome for any
pericyclic reaction. The remaining chapters use this
theoretical framework to show how the rules work with
the other three classes of pericyclic reactions -
electrocyclic reactions, sigmatropic rearrangements and
group transfer reactions. By the end of the book, you
will be able to recognise any pericyclic reaction and
predict with confidence whether it is allowed, and with
what stereochemistry, and you will have a working
knowledge of the range of pericyclic reactions available
to the synthetic organic chemist. |
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