In studying the evolution of organic chemistry and grasping its essence, one comes quickly to the conclusion that no other type of reaction plays as large a role in shaping this domain of science than carbon-carbon bond-forming reactions. The Grignard, Diels-Alder, and Wittig reactions are but three prominent examples of such processes, and are among those which have undeniably exercised decisive roles in the last century in the emergence of chemical synthesis as we know it today. In the last quarter of the 20th century, a new family of carbon-carbon bond-forming reactions based on transition-metal catalysts evolved as powerful tools in synthesis. Among them, the palladium-catalyzed cross-coupling reactions are the most prominent. In this Review, highlights of a number of selected syntheses are discussed. The examples chosen demonstrate the enormous power of these processes in the art of total synthesis and underscore their future potential in chemical synthesis.

Palladium-catalyzed cross-coupling reactions in total synthesis.

Transition-metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes.

Introduction Cationic domino reactions Anionic domino reactions Radical domino reactions Pericyclic domino reactions Photochemically induced domino processes Transition metal catalysis Domino reactions initiated by oxidation or reduction Enzymes in domino reactions Multicomponent reactions Special techniques in domino reactions

Domino Reactions in Organic Synthesis

In organic molecules carboxylic acid groups are among the most common functionalities Activated derivatives of carboxylic acids have long served as versatile connection points in derivatizations and in the construction of carbon frameworks In more recent years numerous catalytic transformations have been discovered which have made it possible for carboxylic acids to be used as building blocks without the need for additional activation steps A large number of different product classes have become accessible from this single functionality along multifaceted reaction pathways The frontispiece illustrates an important reason for this: In the catalytic cycles carbon monoxide gas can be released from acyl metal complexes, and gaseous carbon dioxide from carboxylate complexes, with different organometallic species being formed in each case Thus, carboxylic acids can be used as synthetic equivalents of acyl, aryl, or alkyl halides, as well as organometallic reagents This review provides an overview of interesting catalytic transformations of carboxylic acids and a number of derivatives accessible from them in situ It serves to provide an invitation to complement, refine, and use these new methods in organic synthesis

Carboxylic acids as substrates in homogeneous catalysis.

Claisen rearrangement over the past nine decades.

Palladium-catalyzed hydrogenolysis of allylic and propargylic compounds with various hydrides

Rapidly expanding industrial applications of palladium catalysts as homogeneous and heterogeneous catalysts are surveyed. They are classified into two types. The first type includes the oxidative reactions of olefins and aromatic compounds, and oxidative carbonylation. These reactions are catalyzed by Pd(II) salts and appropriate reoxidants. Reactions catalyzed by Pd(0) complexes are the second type, which includes reactions of organic halides and reactions via π-allylpalladium complexes. Also some promising palladium-catalyzed reactions, which may be used in commercial processes in future, are included. 1. Introduction 2. Oxidative Reactions Catalyzed by Pd(II) Salts 2.1. Oxidative Reactions of Olefins 2.2. Oxidative Reactions of Aromatic Compounds 2.3. Oxidative Carbonylation and Other Reactions 2.4. Summary 3. Reactions Catalyzed by Pd(0) Complexes 3.1. Reactions of Alkenyl and Aryl Halides 3.2. Catalytic Reactions of Allylic Compounds and Conjugated Dienes via π-Allylpalladium Complexes 3.3. Carbonylation of Olefins 4. Concluding Remarks

Expanding industrial applications of palladium catalysts

Both natural and unnatural epimers at C-20 in a steroid side chain can be generated stereospecifically by the palladium-catalyzed hydrogenolysis with triethyl-ammoniuun formate of C-20 (Z) or (E) allylic carbonates, respectively

A novel method for stereospecific generation of either C-20 epimer in steroid side chains by palladium-catalyzed hydrogenolysis of C-20 allylic carbonates

Synthese d'isocarbacycline a partir d'4-acetoxy cyclopent-«2»-enone et de 4-[t-butyldimethylsiloxy] non-«1»-enyl cuivre lithium

A new, highly efficient method for isocarbacyclin synthesis based on tandem Claisen rearrangement and ene reactions

A New Candidate for a Properly Substituted CD Ring Component of Vitamin D3 via Intramolecular Asymmetric Olefination of a 1,3-Cyclopentanedione Derivative

J. Tsuji

Papers

Palladium-catalyzed hydrogenolysis of allylic and propargylic compounds with various hydrides

Expanding industrial applications of palladium catalysts

A novel method for stereospecific generation of either C-20 epimer in steroid side chains by palladium-catalyzed hydrogenolysis of C-20 allylic carbonates

A new, highly efficient method for isocarbacyclin synthesis based on tandem Claisen rearrangement and ene reactions

A New Candidate for a Properly Substituted CD Ring Component of Vitamin D3 via Intramolecular Asymmetric Olefination of a 1,3-Cyclopentanedione Derivative