Methods of Non-a-Amino Acid Synthesis, 2nd Edition

ix

Preface to the Second Edition

The rst edition of this book was published just under 20 years ago. During this

time, many new publications have appeared that expand the synthetic work devoted

to the preparation of non-α-amino acids. This new edition continues the work of

the rst edition to give a representative overview of the synthesis of non-α-amino

acids beginning with the year 1962. New literature references expand this work to

include literature after 1995 through 2012. As with the rst edition, this edition will

focus on acyclic amino acids of C

3

–C

10

, but also aminoalkanoic carboxylic acids,

aminoalkenoic acids, and aminoalkynoic acids. The syntheses of amino carboxylic

acids attached to or incorporated in rings of 3 to 10 carbons are also presented,

including amino cycloalkanoic and amino cycloalkenoic acids. Saturated heterocy-

clic derivatives and aryl-substituted amino acids are discussed once again, but aro-

matic amino carboxylic acids and heteroaromatic amino carboxylic acids are not

discussed, except where they are synthetic precursors to or related to aliphatic amino

carboxylic acids. The rst ve chapters not only illustrate different synthetic strate-

gies to prepare non-α-amino acids, but also serve as a useful review of a variety of

synthetic methodology.

There are signicant differences in this new edition. It has been extensively

rewritten and reorganized. Apart from many updated references, there is a greater

emphasis on the biological importance of non-α-amino acids, and a serious attempt

to limit redundancies. The rst edition was more or less a litany of synthetic meth-

ods, but there were few discussions that concerned why non-α-amino acids are

important. Throughout the new edition there are many brief statements to illustrate

the biological activity of important non-α-amino acids. Further, Chapter 6 in the

new edition is greatly expanded to include several specic classes of non-α-amino

acids with a focus on the biological importance as well as syntheses. The goal is to

push this new edition away from a simple recitation of syntheses and methods toward

a comprehensive discussion of both synthesis and the biological importance of this

class of compounds.

As with the rst edition, synthetic approaches to saturated amino acids of all

types are discussed, as well as unsaturated, alkyl, and aryl-substituted derivatives,

and amino acids that bear a heteroatom functional group. In general, four structural

types of alkenyl amino acids are considered. In the rst type, the double bond can

be conjugated to the carbonyl group and the amine moiety can be attached directly

to the double bond. Second, the amino group can be attached to the saturated carbon

chain. The third and fourth types focus on the double bond, which can be in or out

of conjugation with the carboxyl, and the amine group can be attached anywhere on

the chain. Substituents can appear anywhere on the chain. For alkynyl amino acids,

both conjugated and unconjugated are discussed.

As in the rst edition, this new monograph is divided into seven chapters. However,

the organization and content of these seven chapters are signicantly different. The

rst chapter discusses synthetic methods that rely on substituent refunctionalization.