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Book Review Stereosetective Synthesis. By R. S. Atkinson

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BOOKS
A New Angle on Asymmetric Synthesis
StereoselectiveSynthesis. By R. S. Atkinson. Wiley, Chichester, 1995. 529
pp., paperback &29.95.-ISBN 0471-95250-810-471-95419-5
The subject of stereoselective synthesis
has recently inspired quite a number of
authors. In the case of the book Stereoselective Synthesis by R. s. Atkinson, published last year in a first edition, we even
find that there are “cousins” with the
same name: the Houben-Weyl volumes
E21 a-f and a book by M. Nogridi, both
of which bear the same title.
A glance at the contents of this latest
addition to the family shows that it covers
all the subject areas expected in a work of
this size (see below). The description of
each class of reactions begins with a precise explanation of the underlying principle, based on mechanistic considerations and a transition state model, and
this is followed by a detailed discussion
with suitable examples. This should
provide the reader with a thorough understanding of the causes of the observed
stereoselectivi ty.
When it comes to the arrangement of
the subject matter the author takes a more
exotic line than in his choice of title, as will
appear below. One of the main purposes
of the book is to promote a new way of
classifying stereoselective reactions. This
is based on comparing the number of chiral centers formed in the product molecule
with the number that were present in the
starting molecule. resulting in a classification into five reaction types from 0 to IV.
A reaction of type 0 does not form any
new chiral centers, whereas a type I reaction involves the breaking of one bond at
a chiral center and the stereoselective formation of one new bond. Type I1 reactions are those in which two or more
This section conlains book reviews and a list of
new books
by the editor Book rev,ews are
written by invitation from the editor. Surrestions
for books to be reviewed and for book reviewers
are welcome. Publishers should send brochures or
(better) books to the editorial office: Redaktion
Angewandte Chemle, Postfact, l o l l 6 , , D.6945,
Weinhelm. Germmy. The editor reserves the rieht
o f s e l e c t m which bboks will be reviewed Uniniited books not chosen for review will not be returned.
__
Angeic-. Cliem. In!. Ed Engl. 1996. 35, No. 17
chiral centers are formed simultaneously
from achiral reagent molecules (e.g.,
simple diastereoselection) . In type 111
reactions one or several stereocenters are
formed under the influence of an already
existing stereocenter. The latter reactions
are further divided into several different
sub-groups (types
III’, c , , IIIr,c,
III,,,,,. > and III,,,.,”,”,.). Type IV reactions are those in which no chiral centers
are generated but diastereomers can be
formed (e.g, diastereoselective formation
of an enoiate). Last but not least, it is also
necessary to introduce type II/III reactions, which d o not fit clearly into the
above groups. The system has other weaknesses, which are particularly well illustrated by the fact that the author himself
has not consistently followed this classification as a basis for the structure of the
book! Instead of devoting one chapter to
each reaction type with subdivisions
where necessary, the author has arranged
the contents in 16 chapters, all of equal
status. In some cases a chapter corresponds to a single type, whereas elsewhere
one reaction type is distributed through
up to eight chapters!
Chapter 1 explains the meanings of the
terms used in the book, such as chemo-,
regio-, diastereo-, and enantioselectivity,
chirality, prochirality, homotopy, enantiotopy, and diastereotopy. In Chapter 2
the author briefly explains the system of
classification mentioned above (which is
treated in greater depth in the later chapters). Chapter 3 is concerned with reactions of type 0. The most important part
of this chapter is a table listing enantiomerically pure compounds that are
readily obtainable. The author decribes
how these can be converted into other
enantiomerically pure synthetic building
blocks in which the chiral centers are retained. Still following a logical sequence,
Chapter 4 deals withtype I reactions, beginning with inversion by means of SN2
reactions and continuing- through
- double
inversion (equivalent to retention of configuration) and 1,2-rearrangements, both
with inversion and with retention of configuration, and leading finally to Still’s
cirbanions with a stable configuration. In
Chapter 5 we find the first deviation from
B‘ VCH Veriumaeseiischufr m b H . 0.69451 Weiniieim. 1996
of type I1 reactions this is devoted to some
special type IIIs,c,reactions. Specific reactions discussed here are 1,3 chirality transfers via SN2’reactions, [2,3]-sigmatropic
and [3,3]-sigmatropic rearrangements,
and the ene reaction.
Type I1 reactions are now taken up in
Chapter 6, in which the discussion covers
1,2-additions to olefins, electrocyck reactions, Diels-Alder reactions, and 1,3-dipolar cycloadditions. Even here, however,
the author is innovative, introducing the
terms “inherent diastereoselectivity” and
“occasional diastereoselectivity”, which
have never appeared previously. In Chapter 7 the topic of “occasional diastereoselectivity” is treated in more detail, discussing as examples photochemical
[2 + 21-cycloadditions, photochemical 1,3additions of arenes, 1,3-diyl additions,
palladium-catalyzed
trimethylenemethane additions to olefins, and again [2,3]and [3,3]-sigmatropic rearrangements.
Chapter 8 deals with the aldol addition
and related reactions (still belonging to
type 11). Type 111 reactions are then treated, along with others, in Chapters 9-12.
Here we again find mentions of nearly all
types of reactions in which asymmetric induction is known to occur, ranging from
epoxidation through alkylation reactions
to carbonyl addition reactions. For the
first time the author explains the concepts
of Al.2- and A,,,-strain. already mentioned several times in earlier discussions.
Chapter 13 treats the hybrid type II/III
reactions along with [4 21-cycloadditions, 1,3-dipolar cycloadditions, aldol
additions, and [3,3]-sigmatropic rearrangements.
Chapter 14 returns to type I11 reactions,
and provides examples of catalytic enantioselective reactions (type III,,,,,,,,,~) .
Particular topics treated here are the
Sharpless epoxidation, CBS reduction of
ketones, homogeneously catalyzed hydrogenations, chiral Lewis acids for DielsAlder and ene reactions, the Sharpless dihydroxylation, cyclopropanation reactions, carbonyl additions. and Michael
additions. Type III,,
reactions are covered in Chapter 15, which explains double
stereo-diffeientiation and the meaning of
terms such as “matched” and “mis-
+
,c,C_
0570-0833/96/3517-1997$ 15.00+ .25:0
1997
BOOKS
The sixteenth and final chapter is again
concerned with type I11 reactions. Here
the focus of attention is the distinction between enantiotopic and diastereotopic
atoms o r groups. In addition about 19
pages are devoted to the use of enzymes in
stereoselective synthesis.
At the end of each chapter there is a
summary of the most important points
occupying about half a page. There is an
adequate index containing about 500 entries which include all the important keywords. However, it is annoying that for
some keywords not all the relevant pagenumbers are listed; for example, the entry
for the Diels-Alder reaction fails to refer
to page 417. Altogether there are about
700 literature citations extending u p to
1992.
The author’s use of the word “echt”,
presumably borrowed from German, as in
“the design of echt type IIIr,c, reactions”
(p. 361) struck me as odd. Apart from a
few minor inconsistencies of the kind that
always slip through in the first edition of
any book, I have found only three serious
errors: on pages 21 7, 233, etc. ally1 metal
compounds are repeatedly referred to as
“alkenyl metal compounds”; in Scheme
14b on page 372 the wrong olefin is
shown; thirdly, instead of syn and anti as
introduced by Masamune, the prefixes cis
and trans are incorrectly used.
In any discussions involving stereochemistry the quality of the structural diagrams is of paramount importance. The
perspective formula diagrams used here
for the transition states are clear, but the
mushroom-like appearance of the oxygen
atoms at the ends of the backward-directed bonds (e.g. on p. 27) takes a little getting used to. The “lassos” that are occasionally shown around bonds whose
movement is indicated by arrows (e.g. on
p. 81) convey an odd sense of urgency.
The author’s decision to abandon the
usual order of presentation, based on either the stereoselective synthesis of a particular class of compounds o r the stereochemical aspects of individual reactions
(e.g. the Diels-Alder reaction), has its disadvantages. For example, it results in the
various stereochemical aspects of the
Diels-Alder reaction being treated in a
fragmented way in seven different chapters. The numerous cross-references to
other chapters are therefore really essential. On the other hand, the arrangement
of the subject matter adopted here emphasizes principles of stereoselection that are
common to different reactions, which has
the advantage of focusing the reader’s attention on an interesting new perspective
and helping him o r her to discover new
relationships. Thus, on pages 148ff the
1998
common features linking the epoxidation.
aziridination, and cyclopropanation of
alkenes are discussed, then the reactive
properties of the compounds concerned
are correlated with those of intermediates
in the halogenation of alkenes and of sulfonium and selenium ions in three-membered rings. However, as explained above
this interesting sequence of topics is not
directly derived from the proposed new
system of classification, and therefore the
usefulness of the latter is called into question.
To sum up, the above inconsistency
means that the book is not very suitable
for newcomers to the subject of stereoselective synthesis; on the other hand, for
readers who already have a basic knowledge of the subject it offers new ideas and
insights. It remains to be seen whether this
attempt at a new classification of stereoselective reactions will gain acceptance.
A . Stephen K. Hashmi
Institut fur Organkche Chemie
der Universitlt Frankfurt/Main
(Germany)
Analytical Electrochemistry. By J.
Wang. VCH Publishers, New York,
1994. 193 pp., hardcover $59.95.ISBN 1-56081-575-2
It is pleasing to note that during the last
few years the VCH group has devoted
much effort, with considerable success, to
remedying the relative neglect of electrochemistry in the available literature. Examples of successes in this field are the
new series Frontiers in Electrochemistry,
the journal Electroanalysis, and several
monographs. The latest monograph from
this publishing house is devoted to the
very interesting and highly topical area of
analytical electrochemistry, where new
methods, especially the use of electrochemical sensors, are becoming increasingly important. The choice of this currently highly interesting topic, together
with the expertise of the publishers in this
field and the high reputation of the author, hold out to users of the methods and
to students the promise of an interesting
and valuable book. Regrettably, however,
the reality does not quite come up to these
expectations.
Already in the first short chapter on the
fundamentals we find that there is no
treatment of the electrochemical potential
nor of equilibrium considerations. In the
sections on kinetics one occasionally
comes across mathematical equations
that are incomplete, derivations that are
0 VCH VL.rlugsgeselIsrhufimhH, 0-69451
Wc.inlie~m,1996
not quite correct, and statements that are
rather superficial. The poor quality of the
figures is especially noticeable. The potential is shown increasing either from right
to left or in the opposite sense depending
on the original source. Dimensions are
only partly standardized, and the symbols
used for the same quantity vary from page
to page. For example, A is first introduced
to represent the electrode surface area, but
two pages later is unashamedly used as a
probability factor. Several examples of
computations are given, which at first
seems impressive, but is less helpful than
expected: whereas the user’s difficulties
are most likely to be concerned with dimensions and orders of magnitude, the
computational problem of electroanalysis
(e.g. on p. 103) is cleverly reduced to the
dimensionless problem of the rule of
three.
Chapter 2 is mainly concerned with potential-controlled methods. Here the practitioner will find a collection of information on important instruments, relationships, and new systems. This presentation
is a considerable step forward compared
with the more conventional books by
Plambeck and others. Chapter 3 contains
much valuable practical information, including even the addresses of equipment
suppliers. The sections on modern electrodes are also very useful; aspects such as
special modifications, microelectrodes,
and methods for producing these are included. A chapter on potentiometry is followed by a discussion of biosensors and
chemical sensors; this is interesting and
up-to-date, but not very systematic. The
last 30 pages describe many new developments, in areas ranging from cyclovoltammetry to scanning tunneling microscopy.
The information on the role of electrochemistry as a modern tool of interfacial
science is useful, but is not easy to understand if one is not familiar with the principles.
Thus the book presents in an unusual
way both the successful and the less successful aspects of applied research in this
area. For the practitioner it has a certain
value as a source of information. On the
other hand, the reader who wishes to gain
an understanding of the fundamentals of
electroanalysis and modern electrochemistry will be better served by the more established works on the subject.
0570-0833~96~35/7-i9~8
3 15.00+ .25/0
Joachim Walter SchuEtze
Institut fur Physikalische Chemie
und Elektrochemie
der Universitlt Diisseldorf (Germany)
Angar. Chem. l n l . Ed. Engl.
1996, 35, N o . 17
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