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Modern Rhodium-Catalyzed Organic Reactions. Edited by P. Andrew Evans

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Books
Modern Rhodium-Catalyzed
Organic Reactions
Edited by P. Andrew
Evans. Wiley-VCH,
Weinheim 2005.
473 pp., hardcover
E 149.00.—ISBN
3-527-30683-8
Only a few decades ago, synthesizing
organic compounds with the help of
transition metals was seen as a bizarre
curiosity. That is difficult to grasp for
chemists of my generation, since many
publications in the area of synthetic
organic chemistry now routinely
describe the use of transition-metal
complexes as reagents or—more
often—as catalysts, procedures that are
regarded as perfectly normal. In fact,
their use is so much taken for granted
that the structural formula of the
reagent or catalyst is not even shown
above the reaction arrow, but is replaced
by just the element symbol of the central
metal. Three transition metals—palladium, ruthenium, and rhodium—are
especially important in this context,
not only because they are used very frequently, but especially because of the
wide variety of reactions that they catalyze. Whereas the importance of palladium and ruthenium has been recognized by the publication of many monographs, rhodium remains comparatively
neglected. That serious gap in the literature has now been filled by the book
Modern Rhodium-Catalyzed Organic
Reactions, edited by P. Andrew Evans.
In the books 19 chapters, 31 authors
3802
provide an up-to-date overview of the
many uses of rhodium complexes in
organic synthesis that is, on the whole,
very good.
It begins with a chapter by Y. Chi, W.
Tang, and X. Zhang on what is probably
(along with hydroformylation) the bestknown of all rhodium-catalyzed reactions: asymmetric hydrogenation. The
authors begin by surveying the many different chiral ligands that are used, and
then describe numerous examples to
illustrate the breadth of applications of
the reaction, also including literature
references on the syntheses of natural
products and drugs. Some fundamental
mechanistic studies, such as those by
Halpern and Brown, are not discussed
in detail, although they are mentioned
in a brief historical sketch and are
included in the very comprehensive bibliography.
Chapter 2, by J. M. Brown, is concerned with rhodium-catalyzed hydroboration, and begins with a brief
account of the history of this reaction,
with references to important review articles. That is followed by a description of
recent mechanistic and theoretical studies. The author then describes recent
progress on synthetic applications, with
particular emphasis on chemo-, regio-,
and stereoselectivity. A separate section
is devoted to the attractive topic of
asymmetric catalytic hydroboration.
In Chapter 3, K. Yoshida and T.
Hayashi turn to the subject of conjugated addition reactions. Most of the
chapter is devoted to a discussion of
the stereoselective, and especially the
enantioselective, addition of organoboranes to electron-deficient double bonds.
As well as synthetic applications, the
authors discuss models for understanding the stereochemical course of the
reaction.
In Chapter 4, G. C. Fu discusses two
reactions: asymmetric isomerization of
olefins, and asymmetric hydroacylation.
At first, it seems rather strange to collect
these two reactions together in a single
chapter, although it can be argued that
both processes involve isomerizations.
The first part is devoted to isomerizations of allyl amines, allyl ethers, and
allyl alcohols. Here, most attention is
given to synthetic aspects, whereas
mechanistic problems are only treated
marginally, since these have been cov-
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
ered in recent review articles. The asymmetric hydroacylations described in the
second part of the chapter are used to
synthesize enantiomerically pure cyclopentanones and cyclopentenones. The
chapter also describes examples of reactions in which enantiotopic groups are
efficiently differentiated.
The following chapter is concerned
with hydroformylation. This reaction,
which has long been very important in
industry, has also been used as a synthetic method on the laboratory scale
in recent years. In his contribution,
J. L. Leighton deals mainly with methods for the control of regio- and stereoselectivity, and describes many examples to illustrate the enormous potential
of hydroformylation and silylformylation for the stereoselective synthesis
of highly complex target molecules
such as polyketide natural products.
Chapter 6, by I. Matsuda, is also concerned with C C bond-forming reactions. The first part deals with reactions
based on olefin insertion into the Rh
H bond, while the second part is devoted
to silylcarbonylation reactions. It is
pleasing to find only a small degree of
overlap with the preceding chapter by
Leighton.
In Chapter 7, M. Fujiwara and I.
Ojima discuss the applications of cycloisomerization and cyclotrimerization
reactions,
beginning with cycloisomerizations of various substrates,
with particular attention to the reaction
mechanisms. The rest of the chapter is
devoted to a discussion of cyclotrimerizations and carbonylating cyclotrimerizations. Here too, mechanistic aspects
are considered in detail, with the aim
of bringing clarity to the sometimes
highly complex reaction processes. The
potential of such reactions for synthesizing various target molecules is illustrated by several examples.
In the following chapter, K. M.
Brummond and J. M. McCabe describe
the rhodium-catalyzed Alder–ene reaction. This cycloisomerization reaction
converts dienes, enynes, and allenynes
into carbacycles or heterocycles. The
authors discuss reaction mechanisms
and possibilities for performing the
reaction enantioselectively, as well as
the potential of this type of transformation for syntheses aimed at generating
diversity.
Angew. Chem. Int. Ed. 2005, 44, 3802 – 3804
Angewandte
Chemie
Chapter 9, by K. Fagnou, is devoted
to the rhodium-catalyzed ring-opening
of strained oxygen and nitrogen heterocycles by nucleophiles. The emphasis of
the discussion is clearly on the development of an asymmetric variant of the
reaction, which, starting from prochiral
bicyclic compounds, offers a route for
the stereoselective synthesis of a,bdifunctionalized carbacycles. Separate
sections of the chapter are devoted to
detailed discussions of mechanistic
hypotheses and modeling studies.
Next, in Chapter 10, D. K. Leahy
and P. A. Evans discuss allylic substitution. This reaction is commonly associated only with palladium, but the use
of rhodium catalysts can often give
excellent regio- and stereoselectivities.
From a synthetic standpoint, the strong
preference of the nucleophilic attack
towards the more highly substituted
end of the allylic system is a very attractive feature, as it leads to a terminal olefinic group. The authors describe many
examples to show that rhodium-catalyzed allylic substitution, in combination
with ring-closing olefin metathesis, is an
effective method for synthesizing regioand stereochemically pure carbacycles
and heterocycles. The next three chapters cover the broad field of rhodiumcatalyzed cycloadditions. The article by
N. Jeong (Chapter 11) is concerned
with reactions that yield cyclopentenones. These molecules are accessible
either by a [2 + 2 + 1] cyclization,
which can be regarded as a Pauson–
Khand type reaction, or by a [4 + 1] cyclization from vinyl allenes and carbon
monoxide. In Chapter 12, J. E. Robinson discusses rhodium-catalyzed routes
to six-ring carbacycles by a [4 + 2] cyclization, and to eight-ring carbacycles
through a [4 + 2 + 2] cycloaddition.
This group of chapters on cycloadditions
is completed by a contribution from
P. A. Wender, G. G. Gamber, and T. J.
Williams on the synthesis of seven-membered and eight-membered ring systems
from vinyl cyclopropanes and vinyl
cyclobutanones, by using [5 + 2], [5 +
2 + 1], and [6 + 2] strategies.
Cycloadditions also occupy a large
part of Chapter 14 (H. M. L. Davies
and A. M. Walji), but instead the
common element of the reactions
described here is the involvement of
rhodium-stabilized carbenoids with
Angew. Chem. Int. Ed. 2005, 44, 3802 – 3804
donor–acceptor
functionality.
The
authors begin with strategies for the synthesis of cyclopropanes, cycloheptadienes, and cyclopentenes by cycloaddition reactions. The second part of their
article deals with reactions for inserting
these carbenoids into element H bonds.
Chapter 15, by M. P. Doyle, is also
concerned with rhodium-stabilized carbenoids. Here the topic is the development and use of asymmetric cyclopropanation and C H insertion reactions that
are catalyzed by chiral rhodium-carboximidate complexes. The applications of
both reactions are illustrated by many
examples.
In Chapter 16, D. F. Taber and P. V.
Joshi report on progress in the area of
stereoselective synthesis of cyclopentanes by the rhodium-catalyzed insertion of carbenoids into C H bonds. Auxiliary control and ways of developing an
efficient chiral catalyst are discussed on
the basis of theoretical analyses.
The following chapter, by C. G.
Espino and J. Du Bois, describes oxidative amination reactions. These involve
the intramolecular insertion of nitrogen
functionalities such as carbamates, sulfamates, and sulfonamides into C H
bonds. It is very likely that the reaction
mechanism involves nitrenes. The
authors describe mechanistic studies
along these lines, as well as applications
to the synthesis of target molecules.
Chapter 18 returns to the subject of
the chemistry of rhodium-stabilized carbenes. F. G. West describes processes in
which the primary reaction of the rhodium-stabilized carbene gives an oxonium or ammonium ylide. Under certain
conditions, these reactive intermediates
can undergo rearrangement to give
functionalized heterocycles. Examples
of applications to natural products syntheses are described.
In Chapter 19, R. M. Savizky and
D. J. Austin discuss the formation of
1,3 dipoles by the rhodium-catalyzed
decomposition of diazo compounds,
and the synthetic applications of such
reactions. The dipoles generated in this
way can be used to synthesize a great
variety of complex functionalized heterocycles by 1,3 dipolar cycloaddition.
The authors illustrate this by many
examples in the areas of natural products and drugs.
www.angewandte.org
In this volume, P. Andrew Evans and
the authors of the individual contributions have succeeded in bringing order
to the field of rhodium-catalyzed reactions, which can otherwise be very confusing (at least for nonspecialists). The
chapters are of high quality, both as
regards their content and the standard
of production (especially the figures),
and they provide a good overview of
recent developments in the area. That
is helped by the detailed list of contents
and the good keyword index. Despite
the large number of authors and the
often close relationship between the
topics of different chapters, there is
only a very small amount of overlap,
which is a testimony to the editors efficient work. Experienced synthetic
chemists who wish to learn about
recent developments in the field of rhodium-catalyzed reactions will benefit
especially from reading the book. However, other readers who would also like
to know about the basic principles of
this area of work should find it useful,
as the introductions to the chapters usually provide concise background information and references to important
review articles.
Bernd Schmidt
Institut fr Organische Chemie
Universitt Dortmund (Germany)
DOI: 10.1002/anie.200585297
Acetylene Chemistry
Chemistry, Biology
and Materials Science. By Franois
Diederich, Peter J.
Stang and Rik R.
Tykwinski. WileyVCH, Weinheim
2005. 508 pp.,
hardcover
E 149.00.—ISBN
3-527-30781-8
The publication ten years ago of the
book Modern Acetylene Chemistry,
edited by P. J. Stang and F. Diederich,
2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3803
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