# Book Review Design and Optimization in Organic Synthesis. (Series Data Handling in Science and Technology Vol. 8.) By R

код для вставкиСкачатьBOOK REVIEWS Modern Synthetic Methods 1992. Vol. 6. Edited by R. Schefi .fold. Verlag Helvetica Chimica Acta, Basel/VCH Verlagsgesellschaft, Weinheim/VCH Publishers, New York, 1992. 489 pp., hardcover DM 108.00.-ISBN 3-906390-00-4/3527-28489-311-56081-255-9 The 6th International Symposium on Modern Synthetic Methods was held on the 4th and 5th of May 1992 in Interlaken. The proceedings volume of this latest in a well-established series of symposia contains reviews on the following topics : “Regio- and Stereoselective Formation of Enolates and the Consequences of Enolate Configuration and Subsequent Reactions”, by C. H. Heathcock; “Acetylenes in Synthesis”, by E. Winterfeldt; “Superbases as Powerful Tools in Organic Synthesis”, by M. Schlosser; “Enantiopure Building Blocks from Sugars and their Utilization in Natural Product Synthesis”, by F. W Lichtenthaler; “Carbohydrate Synthesis via Thiazoles”, by A. Dondoni; and “Protective Group Strategies in the Synthesis of Functionalized Carbohydrates”, by C. A. A. van Boeckel. All the contributions reflect the latest state of knowledge, with detailed literature references extending up to 1991. The convenient arrangement of subject matter and the clear schemes make for easy reading. It is pleasing to note that, as a general rule, a reaction arrow represents only a single transformation. All the articles except the one on alkynes contain many examples of laboratory recipes, which enable one to work through the syntheses. Unlike previous volumes there is, for the first time, a subject index, which is a valuable aid when using the book. C. H. Heathcock gives a lucid overview of the chemistry of enolates. from its beginnings up to the present state of knowledge. Reactions leading to regio- and stereoselective formation of enolates are discussed in detail. The author then describes the influence of the configuration of enolates on the stereochemistry of subsequent reactions, especially aldol additions. E. Winterfeldt reports on the latest developments in the use of alkynes in synthesis. These include thermal and organometallic reactions of alkynes, such as [271 + 2nI-cycloadditions, 1,3-dipolar additions, Diels-Alder, en, and pericyclic reactions, free radical and carbene reactions, and reactions of organometallic compounds. Some applications of ionic reactions of alkynes are also described. M. Schlosser deals with the preparation and synthetic applications of superbases. Methods-for forming metalkarbon bonds and for activating metal compounds by forming superbases are described, as well as the use of superbases in An,~yir.C ’ h i , n i . lrit Ed. EnEl. 1992, 31. N o . 10 achieving metalation at aliphatic, olefinic, and heterocyclic positions. The review is completed by examples of arene metalations influenced by neighboring groups, and of regioand stereocontrolled reactions of allylic carbanions prepared from superbases. The use of cheap carbohydrates as precursors for the preparation of enantiomerically pure synthetic building blocks, and their applications in natural products syntheses, are discussed by F. W. Lichtenthaler. The emphasis is on syntheses using simple, easily obtainable reagents and protecting groups, and on avoiding the need for laborious workup procedures. A. Dondoni devotes his contribution to the synthesis of carbohydrates by the addition of aldehydes to thiazole derivatives. By means of this versatile synthetic strategy one can, in a stepwise procedure, stereoselectively build up the carbon skeleton of a sugar around one, two, or three carbon atoms by combining a suitable 2-substituted thiazole derivative with an aldehyde. C. A. A. van Boekel describes syntheses of biologically active oligosaccharides, in particular of heparin fragments. The regio- and stereoselective synthesis of these highly functionalized molecules is achieved by the clever use of appropriate protecting group techniques and glycosidation methods. Each of these articles provides an excellent overview of the topic covered, and offers a rapid way into it for the newcomer. The book can therefore be recommended unreservedly for all synthetic chemists and also for advanced students, and it should be in every chemical library. The sturdy binding (an improvement on the previous paperback volumes) and the careful preparation of the volume, including the index, complete the favorable overall impression. Fritz Theil Zentrum fur Selektive Organische Synthese Berlin-Adlershof (FRG) Design and Optimization in Organic Synthesis. (Series: Data Handling in Science and Technology, Vol. 8.) By R. Curlson. Elsevier, Amsterdam, 1991. XVI, 536 pp., hardcover HFI 330.00.-ISBN 0-444-89201-X During the last few years many books on the design of experiments have been virtually thrown onto the market. It is all the more pleasing, therefore, that Rolf Carlson has allowed time for his contribution to the subject to mature, and has produced a book that is excellent from both the pedagogic and scientific standpoints. It is by no means merely “ ... yet another introductory text on statistics written by a non-statistician”, as Carlson, who is himself an organic chemist at the University of Umea, the stronghold of chemometrics in Sweden, fears in his preface that it might be judged. This book of around 500 pages includes a brief but comprehensive index, a detailed bibliography, references to suitable software, about 30 pages of tables, a few graphics, and a number of detailed examples. There are 19 chapters, six of which might be described as the essential core of the book: “Models as tools” (Ch. 3), “Two-level factorial designs” and “Two-level fractional factorial designs” (Chs. 5 and 6), “Response surface methods” (Ch. 12), “Principal properties” (Ch. 15), and “Quantitative relations between observed responses and experimental variations” (Ch. 17). VCH VerlagrgesrlfschufrmbH, W-6940 Weinhrim, 1992 057n-0833~92j1010-13933 3.50+ ,2530 1393 In “Models as tools” the concept of a model is developed, and the types of models generally used for the design of experiments are described. The reader first encounters statistics towards the end of this chapter, in connection with the validation of models. The two chapters on factorial designs (together with Chs. 4, 7, and 8) contain a detailed treatment of factorial screening, and in particular they explain the connection between calculated primary effects and interaction effects and the response surface models that are treated in more detail in Chapter 12. This chapter also introduces quadratic models and uses this concept to describe the yields of various reactions. Chapter 15 is concerned with principal component analysis, and its application to selecting a few test systems from a very large number of possibilities (different catalysts, solvents, etc.). Chapter 17 then considers how one investigates the effects of the reaction conditions on the most important product characteristics (descriptors), and explains the PLS (partial least squares or projections to latent structures) method. The rest of the chapters serve to put the statistical methods described into the context of organic chemistry. Thus, there are three chapters on strategies (Chs. 1,I3, and 16); these are concerned with general strategies for organic synthesis, strategies for optimizing reaction conditions, and strategies for selecting test systems. Unfortunately, however, there are also three short chapters on optimization methods, which interrupt the flow of the book to some extent, and do not have any direct applications (p. 242: “... applications in organic chemistry are, however, remarkably few”). Possibly these methods have been included in the book so that in later chapters they can serve as a sort of heuristic basis for the selection of suitable test systems, in connection with applications of principal component analysis. To summarize, this book makes worthwhile reading for the organic chemist who would like to plan his or her work a little more systematically, or who simply wishes to find out what statistical methods applied to the design, interpretation, and optimization of experiments are all about. Andreas Orth Hoechst AG Frankfurt am Main (FRG) Principles of Nuclear Magnetic Resonance Microscopy. By P. 7: Cnllaghan. Clarendon Press, Oxford, 1991. XVII, 492 pp., hardcover E 60.00.--ISBN 0-19-853944-4 This monograph is the first handbook devoted to N M R imaging at microscopic resolution. It covers recent technical developments as well as a broad range of applications to biological, mineral, and synthetic materials in a rapidly growing area of research. Examples range from small laboratory animals to eggs, from pathological tissue specimens to plants, and from sandstones to polymers. N M R microscopy is defined as the acquisition of proton N M R images with volume elements smaller than (0.1 mm)3. While two-dimensional images often exhibit an in-plane linear resolution that is about one order of magnitude better than the chosen slice thickness, three-dimensional imaging aims at isotropic spatial resolution. Although the achievable resolution is much coarser than for optical and electron microscopy, significant advantages of the N M R approach are due to (i) the examination of the full three-dimensional structure of a sample without restriction to its surface, (ii) the non-destructive investigation of biological materials or even 1394 f.. VCH Vedagsg~sellsciiufimhH. W-6940 Weinhebn, 1992 living systems. and (iii) the potential for dynamic studies of functional properties. Although not specifically indicated, the book is structured into three main parts. complemented by a small section on hardware considerations. The first part of the monograph comprising Chapters 1-3 (170 pages) deals with imaging principles, basic NMR, and magnetic field gradients in N M R imaging, respectively, and thus covers the whole range of essentials for microscopic imaging by NMR. More difficult theoretical parts may be skipped by the neophyte, but will turn out to be useful for a rigorous treatment at later stages. In addition, principles such as the Fourier transformation and the convolution theorem are discussed with many illustrative examples and figures. The introduction to N M R is confined to some basic quantum mechanics emphasizing the classical treatment (Bloch equations) of magnetizations subject to simple radiofrequency (r.f.) pulse sequences (excluding two-dimensional N M R spectroscopy). The use of magnetic field gradients for N M R imaging is discussed in great detail. Starting from spin density projections of a sample obtained by acquiring its N M R signal in the presence of a magnetic field gradient, the chapter describes slice-selective excitation, N M R image reconstruction, and actual r.f. pulse and gradient sequences popular in medical N M R imaging. The second part formed by Chapters 4 and 5 (150 pages) focusses on the principles and applications of N M R microscopy. Limitations of the spatial and temporal resolution are addressed that are due to the achievable signal-to-noise ratio (SNR), short N M R relaxation times, molecular selfdiffusion and other motions (macroscopic movements, flow, intracellular streaming, fluid penetration of solid materials. swelling of polymers, etc.), and the presence of magnetic field inhomogeneities caused by susceptibility differences in the sample. An almost complete summary of applications is given that creates a realistic picture of the state of the art (1990). by presenting numerous examples from both the “liquid” phase and the solid state. Where appropriate, the applications are accompanied by further detailed descriptions of more complex N M R techniques. For example, microscopy studies of nuclei other than protons may require heteronuclear polarization transfer to improve the SNR, while N M R imaging of solid specimens may be performed in conjunction with spectral line-narrowing by multi-pulse techniques and/ or magic angle spinning synchronized to rotating magnetic field gradients. The third part, Chapters 6-8 (120 pages), expands in considerable detail on the relevance of translational motions for N M R microscopy. Following largely theoretical discussions of various types of mobility and their effects on the N M R signal, more practical aspects are concerned with NMR imaging methods to visualize or even quantitatively determine properties such as anisotropic and/or restricted diffusion. or spatial distributions of flow velocities. The final chapter (20 pages) discusses the design of optimized gradient coils for generating strong, uniform, and time-varying magnetic field gradients as required in high-resolution N M R imaging. A strength of this book is a detailed and comprehensive coverage of N M R imaging, including fundamental N M R techniques and mathematical treatments. This provides the necessary background information, particularly for those readers who are primarily concerned with microscopy as a problem-solving tool, but have little or no experience in NMR. However, my feeling is that many parts will be best appreciated by physicists, but not so easily followed by specialists from other areas of this multidisciplinary field. Microscopy studies are extensively discussed in a major part of the book and include many up-to-date examples. The tabu- 0570-0X33/92!101(~-1394 5 3.50f .ZS,/O Ari,qew. Ciiem. I n t . Ed. EngI 1992, 3f. No. 10

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