Radical Reactions of Carbohydrates

Volume I: Structure and Reactivity of Carbohydrate Radicals

Volume II: Radical Reactions in Carbohydrate Synthesis

Preface

Radical reactions provide a varied and powerful means for transforming carbohydrates. The importance of these reactions has steadily grown over the past several decades. Although the study and investigation of new reactions continue, an increasing amount of effort is directed toward application of radical reactions to synthesis of carbohydrates and carbohydrate-containing materials. Much of this effort is concerned with preparation of biologically active compounds. There is also considerable interest in determining the roles of radical reactions of carbohydrates in living systems. As this turn toward applying and understanding radical reactions in biological settings takes place, the time seems right to consolidate what is known about carbohydrate radicals and their chemistry. This consolidation takes place in the two of books on "Radical Reactions of Carbohydrates" found on this website.

"Volume I: Structure and Reactivity of Carbohydrate Radicals" is the first of these two books about carbohydrate radicals and their reactions. Volume I contains eleven chapters that describe the basic chemistry of carbohydrate radicals. The first of these chapters briefly outlines the emergence of radical reactions in organic chemistry and links these reactions to carbohydrates. The next two chapters introduce radical chain (Chapter 2) and nonchain (Chapter 3) reactions. Chapter 4 catalogs and illu­strates elementary radical reactions of carbohydrates, and Chapter 5 shows how these reactions are combined into sequential processes. Once a foundation has been established by the first five chapters, discussion turns to how structure (Chapter 6), philicity (Chapter 7), and reaction rates (Chapter 8) of radicals affect their reactivity. The final chapters build on the information from earlier ones to explain how the more complex phenomena of chemoselectivity (Chapter 9), regioselectivity (Chapter 10), and stereoselectivity (Chapter 11) are applied to understanding radical reactions of carbohydrates.

Volume I is directed toward a broad range of scientists. It provides the information needed for an individual to start with a basic understanding of organic chemistry and reach the current level of understanding of the radical chemistry important in the study of carbohydrates. This book also serves as a resource for experienced researchers who may wish to review some aspect of the chemistry of carbohydrate radicals and, at the same time, find references to the primary literature. Other scientists who may find this book useful are persons whose primary interest is in radical chemistry but who recognize the expanded understanding of radicals that comes from studying reactions of carbohydrates, that is, reactions of polyfunctional molecules that differ in stereochemistry in a systematic way. 

"Volume II: Radical Reactions in Carbohydrate Synthesis" is a book containing twenty-four chapters that describe and analyze radical reactions as they are used in carbohydrate chemistry. This book is divided into six sections. The first section is preceded by an introductory chapter that catalogs the advantages and disadvantages of radical reactions and illustrates each with a reaction of a carbohydrate. Section I consists of Chapters 2-7 and is devoted to reactions of compounds (e.g., halides, sulfides, and selenides) where the initial reaction is the cleavage of a sigma bond. Section II, which contains Chapters 8-10, broadens the scope of possible substrates to include compounds where bond cleavage is facilitated by the presence of a multiple bond containing an oxygen atom. Section III is a sequence of three Chapters (11-13) that focuses on reactions of compounds with carbon-sulfur double bonds. A collection of four Chapters (14-17) that describe the radical reactions of nitrogen-containing compounds (e.g., nitro compounds, azides, isonitriles, and oxime ethers) make up Section IV. Section V has two large chapters that describe reactions of radicals with carbon-carbon multiple bonds. The first of these (Chapter 18) involves radical addition reactions, and the second (Chapter 19) focuses on radical cyclization reactions. The final Section (VI) consists of five Chapters (20-24) that describe how transition-metal complexes are used either to generate carbohydrate radicals or form radicals that react with carbohydrates. Following Chapter 24 is Appendix I, which catalogs the various hydrogen-atom donors used in radicals reactions. This Appendix also addresses the problems associated with each donor and discusses the solutions to these problems that have been developed. 

"Volume II: Radical Reactions in Carbohydrate Synthesis" is a book that should be of particular interest to individuals using or planning to use radical reactions in the synthesis of carbohydrates or carbohydrate-containing compounds. Because the usefulness of radical reactions now has reached the point where anyone involved in carbohydrate synthesis needs to consider the possibilities offered by radical reactions, interested individuals could include anyone involved in the synthesis and/or transformation of carbohydrates. The information and analysis contained in Volume II (and, as already mentioned, in Volume I) should be valuable to persons studying radical reactivity in molecules with multiple chirality centers.

Finally, we wish to acknowledge Oberlin College and, in particular, the Oberlin College Science Library for making available the books and journals we needed for our research. The Library either contained or provided access to all the literature we required for our writing. Whenever we encountered difficulty in obtaining information, Alison Ricker and Jennifer Schreiner, the Science Librarians, were knowledgeable and helpful in solving the problem.