Highlights of Boron Chemistry

The chemical behavior of boron is strikingly different from that of the other Group 3A(13) members. Boron forms network covalent compounds or large molecules with metals, H, O, N, and C. Many boron compounds are electron deficient, but boron fills its outer level in two ways  

Accepting a bonding pair from an electron-rich atom. In gaseous boron trihalides, B has only six electrons around it (Section 10.1). To attain an octet, it accepts a lone pair from an electron-rich atom and forms a covalent bond  

Similarly, B has only six electrons in boric acid, B(OH)3 (sometimes written as H3BO3). In water, the acid itself does not release a proton, but it bonds to the O of H2O, which then releases an H ion  

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The book highlights the latest developments in all areas of boron chemistry. These encompass a variety of topics, including theoretical and spectroscopic studies and applications in organic synthesis and medicinal chemistry, in which boron neutron capture therapy features prominently. 

A Dalton Transactions feature article by N. N. Greenwood entitled Main group chemistry at the millennium, in which the highlights of main group (including boron) chemistry over the last decade are reviewed.10... 

In the following, the known boron derivatives of pyrazoles are discussed but without consideration of the historical development. Specific properties are highlighted which illustrate not only the usefulness of many of these compounds but also their potential for studying fundamental aspects of contemporary chemistry. 

Summary Precursor-derived quaternary Si-B-C-N ceramics frequently possess an enhanced thermal stability compared to SiC, SisN4 or Si-C-N ceramics. The stability of the materials towards crystallization and/or decomposition is directly coimected to the molecular structure and the elemental composition of the polymeric precursors. This paper highlights recent investigations on the synthesis of boron-modified polysilazanes and polysilylcarbodiimides. Hydroboration of polyvinylsilazanes and dehydrocoupling reactions of boron-modified silanes with ammonia or amines as well as cyanamide are described. It is shown that simple organosilicon chemistry provides a means to efficiently optimize ceramic yields and tune elemental composition as well as thermal properties of the polymer-derived ceramics. 

This chapter is intended to highlight the synthesis and use of geminal bimetallic compounds such as gem-metallozirconocenes, but we will concentrate on the chemistry of aluminum, boron, lithium, gallium, germanium, tin, zinc, and zirconium. 

This chapter will attempt to summarize selected key learnings and trends, and will also highlight recent developments of these methods solely devoted to the copper-catalyzed oxidative arylations of O—H and N—H bonds with boron-based arylating reagents. Further, it will detail some specifics that have brought the method to its current high levels of popularity within the synthetic organic chemistry community. 

The example below highlights the question of whether parallel or miero-wave chemistry (MW) would have a significant effect on MI in the medieinal chemistiy environment. As an example, comparison of a multimode MW and single mode MW have been used. The reaction studied was a Suzuki-Miyaura reaetion with the aim to compare different catalysts and boron-sources like boronie acid, boronic acid ester and trifluoroborates (Figure 9.10). ... 

Researchers fundamentally interested in C-C bond-forming methods for polyketide synthesis have at times viewed allylation methods as alternatives, and maybe even competitors, to aldol addition reactions. Both areas have dealt with similar stereochemical problems simple versus absolute stereocontrol, matched versus mismatched reactants. There are mechanistic similarities between both reaction classes open and closed transition states, and Lewis acid and base catalysis. Moreover, there is considerable overlap in the prominent players in each area boron, titanium, tin, silicon, to name but a few, and the evolution of advances in both areas have paralleled each other closely. However, this holds for an analysis that views the allylation products (C=C) merely as surrogates of or synthetic equivalents to aldol products (C=0). The recent advances in alkene chemistry, such as olefin metathesis and metal-catalyzed coupling reactions, underscore the synthetic utility and versatility of alkenes in their own right. In reality, allylation and aldol methods are complementary The examples included throughout the chapter highlight the versatility and rich opportunities that allylation chemistry has to offer in synthetic design. 

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