Specific Synthetic Methods

Van Tamelen (I24a) has reported a useful and specific synthetic method for the production of enamines by the oxidative decarboxylation of N,N-dialkyl a-amino acids with sodium hypochlorite. 

Similar procedures as described in the previous sections are still valid for the preparation of these compounds, but there are some specific synthetic methods which warrant attention. 

The Diels-Alder reaction is a very valuable approach in classical annelation sequences of PAHs and is intensely documented in the reviews on the synthesis of aromatic hydrocarbons [26]. Therefore, we will describe herein only some few, selected, modern applications of the Diels-Alder reaction that caught our interest. To avoid any misunderstanding, the authors will absolutely not pass any judgement on a specific synthetic method by using the terms classical and modern . 

Probably the first synthesis of a pteridine to be carried out was via a ring transformation of a purine long before the structure of organic molecules was understood. Wohler heated uric acid and water to obtain compounds, later shown to be pteridines, as early as 1857.1 A number of such ring transformations of purines, and of other heterocyclic systems, have now been recorded. However, they are rarely useful as specific synthetic methods for pteridines, the yields are frequently low, and only two examples will be given here. 

Two methods will be presented here, the first being the specific synthetic method for LSD given in example ten of US Patent 2,774,763. The other is the general method given in Journal of Organic Chemistry Volume 24, pages 368 to 372. Both are authored by William Garbrecht, a true hero of LSD synthesis. The patent dates from 1955, while the Journal article dates from 1958.1 leave it to the serious experimenter to decide which is more advanced. No doubt, both are operable. 

The nanoplatform production relies on advances in nano-scale production. The production methods are based on relatively simple wet chemistry techniques, as opposed to many complicated physical and chemical nanotechnology schemes. Specific synthetic methods for nanoparticles of different matrices are optimized to produce the nanoplatforms of a specific matrix and loaded with components for a particular application. The batch-to-batch reproducibility of the nanoplatforms is good and the optimized synthetic protocol is reliable to produce the required nanoplatforms. 

Morphological features are difficult to observe in solid-state NMR spectra of common polymers. However, if the polymer is thermally treated, immersed in a constrained environment, or is produced by specific synthetic methods, different phases can arise and these phases can be detected in the solid-state NMR spectrum or by NMR relaxation measurements. 

Best Synthetic Methods is now 10 years old, is a family of 16 volumes and has been well received by the majority of chemists as a valuable aid in their synthetic endeavours, be they academic or commercial. The focus of the series so far has been on special methods, reagents or techniques. This volume is the first of a new sub-series with a focus on heterocycles and their synthesis. It is amazing the extent to which each heterocyclic type has its own specialized synthetic methodology. Whether the chemist is endeavouring to make a heterocycle by ring synthesis or wishes to introduce specific substituents, it is the intention that this new development will serve their needs in a practical, authoritative, fully illustrative and compact manner. Richard Sundberg is an authority on indole chemistry and it is a pleasure to have such a noted heterocyclist to initiate this venture. 

In this section, only salient features of the synthesis, physicochemical properties, and reactivity of major derivatives of 2-aminothiazole and 2-imino-4-thiazoline are summarized. Further details on each compound are found in associated references collected in Section VII. The synthetic methods reported in this section exclude heterocydization methods treated in Chapter II but given in specific references found in Section VII. 

Part Two, a collection of multistep syntheses accomplished over a period of more than three decades by the Corey group, provides much integrated information on synthetic methods and pathways for the construction of interesting target molecules. These syntheses are the result of synthetic planning which was based on the general principles summarized in Part One. Thus, Part Two serves to supplement Part One with emphasis on the methods and reactions of synthesis and also on specific examples of retrosynthetically planned syntheses. 

The lack of significant vapor pressure prevents the purification of ionic liquids by distillation. The counterpoint to this is that any volatile impurity can, in principle, be separated from an ionic liquid by distillation. In general, however, it is better to remove as many impurities as possible from the starting materials, and where possible to use synthetic methods that either generate as few side products as possible, or allow their easy separation from the final ionic liquid product. This section first describes the methods employed to purify starting materials, and then moves on to methods used to remove specific impurities from the different classes of ionic liquids. 

This volume of Organic Syntheses contains twenty-seven checked procedures of value to the modern practicing chemist. One hopes it will also serve to attract students to the charms of skillfully planned and executed experimental work. The majority of the preparations represent specific examples of important, often recently discovered synthetic methods with general applicability. As in previous volumes the preparation of a number of reagents and widely used starting materials is also included. 

The electrochemistry of conducting polymers has been the subject of several reviews2-8 and has been included in articles on chemically modified electrodes.9-14 The primary purpose of this chapter is to review fundamental aspects of the electrochemistry of conducting polymer films. Applications, the diversity of materials available, and synthetic methods are not covered in any detail. No attempt has been made at a comprehensive coverage of the relevant literature and the materials that have been studied. Specific examples have been selected to illustrate general principles, and so it can often be assumed that other materials will behave similarly. 

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