Discovery research versatility

The following is a comprehensive smwey of the chemistry of macrocycles comprised entirely of phenyl and acetylenic moieties. Although over fom" decades old, this area of research has come into its own just in the last few years. Widespread interest in the field has been spurred by recent discoveries utilizing these compoimds as ligands for organometallic chemistry, hosts for binding guest molecules, models of synthetic carbon allotropes, and precursors to fullerenes and other carbon-rich materials. This review will discuss the preparation of a tremendous variety of novel structm-es and detail the development of versatile synthetic methods for macro cycle construction. 

The importance of this sensational discovery for biogenesis research only became apparent in the next few years (Lahav, 1999). It is clear that prebiotic chemistry is much more complex and versatile than was thought about 50 years ago, when Stanley Miller carried out his first successful amino acid syntheses. Experiments similar to the ones described above, as well as new ones which must first be devised, could help to slowly close the wide gap which still exists between the prebiotic and the living worlds (Wills and Bada, 2000). 

These examples of the use of microwave irradiation in the synthesis of heterocyclic compounds show the great versatility of this technique, which can be used under a variety of experimental conditions. Even when there is no improvement of yields, or rates, or specificity, the technique is worthwhile owing to its simplicity. It can be foreseen that microwave ovens are going to be among the basic equipment of research laboratories in the near future. Combinatorial and parallel synthesis under the action of microwave irradiation is becoming a powerful tool for discovery of new molecules and should develop very rapidly. 

The isolation of physiologically active natural products and the determination of the chemical basis for their activity, the study of insect biochemistry, and the investigation of the chemical basis for host selection are current areas of research activity which should be of particular interest to the pesticide chemist for it may be anticipated that an important "spin-off" of this research will be the discovery of new and safer organic pesticides. It may also be anticipated that a substantial number of these new pesticides will incorporate that most versatile element, sulfur. 

In the late 1970 s, Kirchhoff at The Dow Chemical Company initiated a research program on the use of benzocyclobutenes in polymer synthesis and modification. These efforts culminated in 1985 with the issuance of the first patent on the use of benzocyclobutenes in the synthesis of high molecular weight polymers [3]. Similar work was reported separately and independently by Tan and Arnold working at the Air Force Wright Laboratories [11-14], Since these initial discoveries, the field of benzocyclobutene polymers has rapidly expanded to include currently 75 issued patents and numerous publications by a variety of researchers. These numbers are expected to increase considerably since benzocyclobutenes constitute the basis of a new and versatile approach to the synthesis of high performance polymers for applications in the electronics and aerospace industries. 

Since its inception about 15 year ago, MALDI-IMS has been developed into a powerful and versatile tool for biomedical research. It allows for the investigation of the spatial distribution of molecules at complex surfaces. The combination of molecular speciation with local analysis makes a chemical microscope that can be used for the direct biomolecular characterization of histological tissue section surface. However, successful detection of the analytes of interest at the desired spatial resolution requires careful attention to several steps in the IMS protocol matrix selection, matrix coating, data acquisition, and data processing. MALDI-IMS is increasingly playing an important role in the drug discovery and development and disease treatment. 

The field of homogeneous palladium catalysis traces its origin to the development of the Wacker process in the late 1950s (Eq. 7) [83]. Since this discovery, palladium-catalyzed reactions have evolved into some of the most versatile reactions for the synthesis of organic molecules [84,85]. Palladium-catalyzed Wacker-type oxidation of alkenes continues to be an active field of research [86-88], and several recent applications of NHC-coordinated Pd catalysts have been reported for such reactions. 

The development of ruthenium complexes for other applications in radical chemistry is still in its infancy, but seems well suited to future expansion, thanks to the versatility of ruthenium as a catalytically active center. Large avenues have not been explored yet and remain open to research. For instance, the development of methodologies for the asymmetric functionalization of C-H bonds remains a challenge. The Kharasch-Sosnovsky reaction [51,52],in which the allylic carbon of an alkene is acyloxylated, its asymmetric counterpart, and the asymmetric version of the Kharasch reaction itself are practically terra incognita to ruthenium chemistry, and await the discovery of improved catalysts. 

More than forty years after its serendipitous discovery in 1951 [1], ferrocene still enjoys a great deal of interest from scientists in many areas of research. Due to its high stability and the well-established methods for its incorporation into more complex structures, ferrocene has become a versatile building block for the synthesis of compounds with tailor-made properties. 

This paper has provided, we believe, a comprehensive, up-to-date, critical, and objective review on the discovery and the subsequent fast development of living radical polymerizations catalyzed by transition-metal complexes in the period from 1994 to early 2001. These metal-catalyzed living radical polymerizations have rapidly been developing since their discovery in 1994, and the scope of applicable monomers, metal catalysts, and initiators has been expanding. Their advantages include versatility toward a variety of monomers, feasibility in a wide range of reaction conditions, and relatively easy access to the materials. This permits many researchers to use the systems for the precision synthesis of various polymers with controlled architectures. 

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