Iridium Complexesin Organic Synthesis

Catalysis of organic reactionsby the platinum group metals is a

cornerstone of modern chemistry, interms of both fundamental research

and industrial applications. Of these tran-sition metals, those from the 4d series (Ru,

Rh, Pd) are generally perceived to be the moreactive catalysts for organic transformations, whilethose from the 5d series (Os, Ir, Pt) are oftenviewed as more inert, while providing usefulmodels for reactive complexes from the secondrow. In reality, there are many exceptions to thisgeneral perception, and many useful catalystsbased on the heavier metals are known. This bookis the first to provide comprehensive coverage ofthe application of one of these metals, iridium, inorganic synthesis. An impressive list of authors hascontributed 15 chapters that review progress acrossthe full range of current research in this area.

In the opening chapter, Blaser gives a conciseand authoritative overview of the application ofiridium catalysts in the fine-chemicals industry. Thisincludes an iridium–diphosphine-catalyzed iminehydrogenation process (developed by Ciba-Geigy,now Solvias) for production of the herbicide (S)-metolachlor, which is currently the largest com-mercial application of enantioselective catalysis.Potential opportunities for the development of newiridium-based fine-chemicals processes are alsoconsidered by Blaser.

Chapters 2 and 3 deal with the organometallicchemistry of particular classes of iridium complexand their catalytic applications. Oro discussestriisopropylphosphine complexes and their behav-ior in hydrogenation reactions, while Peris andCrabtree review the recent growth in the use of N-heterocyclic carbene ligands in iridium chemistryand catalysis. In both chapters there is an emphasison the fundamental organometallic chemistry andmechanistic aspects. The following two chaptersfocus on hydrogenation and hydrogen-transferprocesses, an area of substantial research interest.

Bianchini and co-authors provide detailed cov-erage of C=O hydrogenation reactions, with par-ticular emphasis on the wide variety of ligands thathave found use in these processes. Fujita andYamaguchi then review the use of pentamethyl-cyclopentadienyl iridium complexes in hydrogen-transfer reactions. A chapter by Dorta on hydro-amination of alkenes and alkynes gives extensivecoverage to both the catalytic behavior and reac-tion mechanisms. This is followed by an informativereview of boron addition reactions by Fern�ndezand Segarra.

A chapter by Kalck and Serp, dealing with thecarbonylation of methanol, illustrates how an

iridium catalyst can compete effectively with anestablished and successful rhodium-based process.

Asymmetric allylic substitutions catalyzed byiridium complexes are addressed by Helmchen,with reactions of C, N, and O nucleophiles beingconsidered in turn. Carbon–carbon (and carbon–heteroatom) bond-forming reactions are covered inchapters by Ishii and co-authors (coupling reac-tions) and Shibata (cycloadditions). Albrecht andMorales-Morales then review the application ofiridium pincer complexes in a range of bond-activation processes.

Iridium has played a significant role in thedevelopment of C�H activation chemistry, and thisis further exemplified in the subsequent chapter byMorales-Morales on alkane dehydrogenation. Therecent combination of iridium pincers with molyb-denum alkylidene complexes to give a “tandem”catalyst for alkane metathesis provides a notabletopical example in these sections. Marciniec andKownacki describe iridium catalysts for transfor-mations of organosilicon compounds and, in thefinal chapter, Scholten and Dupont review thecatalytic properties of soluble iridium nanoparti-cles, another topic of growing importance.

It is apparent, from the large number ofcatalytic reactions covered, that iridium complexesare active for a very wide range of organicprocesses and that informed choice of appropriatesupporting ligands and reaction conditions is key tothe development of efficient catalysts. For anyresearcher working in the field of homogeneouscatalysis, this book will certainly prove useful formaking such selections and designing new catalysts.It also gives considerable insight into the funda-mental organometallic chemistry and underlyingreaction mechanisms. As well as providing histor-ical context, the book also includes many illumi-nating examples from the recent literature, repre-senting the current state of the art. It is expertlyedited by Oro and Claver who are widely recog-nized for their expertise in organometallics andcatalysis. The index enables cross-referencing tolink themes from different chapters.

In summary, both academic and industrialpractitioners of transition-metal catalysis and orga-nometallic chemistry will find this volume to be avery useful addition to their bookshelves. I wouldalso recommend it for university library collections,where it will prove to be a valuable referencesource for graduate students.

Anthony HaynesDepartment of ChemistryUniversity of Sheffield (UK)

DOI: 10.1002/anie.200903039

Iridium Complexes inOrganic SynthesisEdited by Luis A. Oro andCarmen Claver. Wiley-VCH,Weinheim 2008. 396 pp.,hardcover E 139.00.—ISBN978-3527319961

AngewandteChemieBooks

5993Angew. Chem. Int. Ed. 2009, 48, 5993 � 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim