Categories: Organic Chemistry >> Synthesis >> Microwaves

Microwaves in Organic and Medicinal Chemistry

Description

A handy guide for organic and medicinal chemists focusing on common reaction types in medicinal chemistry, including solid-phase and combinatorial methods. Microwave theory, latest developments in instrumentation and a variety of examples from the recent literature are included.

Editorial Review

Within a very short period of time, microwave synthesis has developed into a tool to be taken seriously. The short reaction times and improved yields offered by this methodology have piqued the interest of industry, particularly in the area of drug development. Since several manufacturers of professional-grade equipment have arrived on the scene, and the further development of the technique has proceeded apace (e.g. from multi-mode to single-mode, and above all the use of synthesis robots), one can only conclude that this interest continues to grow.

Oliver Kappe took on combinatorial chemistry at an early stage, and now has finally tackled Microwave Assisted Organic Synthesis (MAOS). Good contacts with industry and with the manufacturers of the abovementioned apparatus qualify this author as an ideal middleman, who is aware of the needs of industry, and who has already tested equipment from all of the makers. In this regard, the presentation covers currently available technology that is state of the art, which can be helpful in making purchase decisions.

The advantages of microwave synthesis over the conventional practice of running reactions in an oil bath are explained briefly, while the focus is on the use of professional, pressure-capable equipment. Thermal effects, in particular the homogeneity of heat generation, and superheating (of common solvents) are a few of the reasons that reactions are accelerated many fold, and proceed with fewer side-products being formed. Specific microwave effects are observed in only rarest of circumstances. In contrast to earlier books on the topic, the present monograph has a predominantly pragmatic, application-oriented approach; the reader is spared any philosophizing about the nature of microwave acceleration. Factual information on solvents, temperature measurement, and sources of potential hazards are the primary focus, so that the novice can readily locate what is worth knowing along with some impressive arguments in favor of using MAOS.

The multitude of examples from the current literature is especially interesting. A differentiation is made here between General Organic Synthesis and Combinatorial Chemistry / High-Throughput Organic Synthesis. The timeliness of the contributions from the literature in the General Organic Synthesis is impressive, which is evident in an example of a transition metal-free Suzuki-type coupling - Kappe has incorporated the latest corrections by the authors, which were only published shortly before the present volume went to press. In addition to cross-couplings, one finds an abundance of other transformations: from Diels-Alder to oxidations, hydrogenations under pressure, Michael additions, decarboxylations and heterocycle syntheses. The chapter on the application of microwave synthesis to combinatorial chemistry goes into detail regarding solid-phase synthesis, as well as solid and fluorous phase-bound reagents, and explains the fundamentals (e.g. polymer stability, suitable solvents) before delving into the current literature citations.

With so many possibilities made available with MAOS, and the time available for optimizing a reaction being often so short, chemists really cannot afford to leave the potential of this methodology unexploited. By providing an introduction, an up-to-date survey of available equipment, and pertinent literature citations, the book “Microwaves in Organic and Medicinal Chemistry” welcomes the reader into this exciting field.

Contents

Introduction: Microwave Synthesis in Perspective
MICROWAVE THEORY
Microwave Radiation
Microwave Dielectric Heating
Microwave versus Conventional Thermal Heating
Microwave Effects
EQUIPMENT REVIEW
Domestic Microwave Ovens
Microwave Reactors for Organic Synthesis
Multimode Instruments
Single-Mode Instruments
MICROWAVE PROCESSING TECHNIQUES
Solvent-free Reactions
Phase-Transfer Catalysis
Reactions Using Solvents
Parallel Processing
Scale-Up in Batch and Continuous Flow
GETTING STARTED WITH MICROWAVE CHEMISTRY
Why Use Microwave Reactors?
Translating Convenionally Heated Methods
Reaction Optimization and Library Generation
Limitations and Safety Aspects
LITERATURE SURVEY: GENERAL ORGANIC SYNTHESIS
Transition Metal-catalyzed Carbon-Carbon Bond Formation
Transition Metal-catalyzed Carbon-Heteroatom Bond Formation
Other Transition Metal-mediated Processes
Heterocycle Synthesis
LITERATURE SURVEY: COMBINATORIAL AND HIGH-THROUGHPUT SYNTHESIS
Solid-Phase Organic Synthesis
Soluble Polymer-supported Synthesis
Task-specific Ionic Liquids
Fluorous Synthesis
Polymer-supported Reagents, Catalysts and Scavengers