CHAPTER 5
5 FIVE-MEMBERED HETEROCYCLES
The specific chapter to which a given drug is assigned is to some extent
arbitrary. More than a few compounds in the preceding chapters included
a heterocyclic ring in their structures. That fragment more often that not,
however, comprised a cyclic base, for example, piperidine. The compound
in question was not classified as a heterocycle as it is quite likely that it
would show the same qualitative biological activity if that moiety was
replaced by a noncyclic base. Heterocyclic moieties do, however, seem
to play a role in the biological activity beyond simply providing a basic
center for a good many agents. Compounds 7 and 18 provide a particularly
apt example; the pyrrolidine ring in these enzyme inhibitors acts as a sur-
rogate for a proline moiety that occurs in the natural substrate. Compounds
meeting that criterion will be found in this and the following sections. Note
that close to two-thirds of the compounds in this volume have been judged
to meet that criterion and will be met in the following chapters.
1. COMPOUNDS WITH ONE HETEROATOM
The protease enzyme dipeptidal peptidase (DPP) is closely involved in
glucose control. This enzyme regulates levels of the hormone-like
The Organic Chemistry of Drug Synthesis, Volume 7. By Daniel Lednicer
Copyright#2008 John Wiley & Sons, Inc.
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