Boron compounds synthesis

Boron-sulfur bonds, addition, to alkynes, 10, 778 Boron trihalides, in boron compound synthesis, 9, 146 Boron-zinc exchange and copper-catalyzed substitutions, 9, 518 for organozinc halide preparation, 9, 89 Borostannylation, enynes, 10, 334... 

Various borate esters are chemostetilants for house flies (51). Tributyl borate, available from Eagle-Picher, Miami, Oklahoma, which is isotopically enriched in boron-10, is being used as a chemical precursor in the synthesis of pharmacologically active boron compounds suitable for boron neutron capture therapy. 

Borane complexes are the most widely used commercial boron compounds, after sodium borobydride. Examples used in organic synthesis are amine borane complexes and borane complexes of tetrahydrofuran and dimethyl sulfide. 

Allenyllithium reagents are commonly prepared through lithiation of propargylic halides or by deprotonation of alkynes or certain allenes (Eq. 9.1). Lithiated allenes often serve as precursors to stable allenylmetal compounds such as stannanes or silanes. They can also be employed for the in situ synthesis of allenylzinc, -titanium and -boronate compounds, which can be further transformed to substitution products not accessible from their allenyllithio precursors. 

With the development of CO 2 lasers, work on the infrared photochemistry of boron compounds is now appearing in the literature. Future woric on these compounds with UV laser sources is also expected. In this review the effect of radiation on boron compounds in the photon energy range 0.1 eV (CO2 laser) to 10.2 eV (H-a line) is examined. The range of tropics extends from the use of photochemical techniques for synthesis of new compounds to the production and isolation of reactive photochemical intermediates. The photochemistry of borazine is most extensively discussed. 

Addition reactions of allylic boron compounds have proven to be quite general and useful. Several methods for synthesis of allylic boranes and boronate esters have been developed.36 37 The reaction has found some application in the stereoselective synthesis of complex structures. 

Boric oxide is used to produce many types of glass including low-sodium, continuous filaments for glass-belted tires, and fiberglass plastics. It also is used to make ceramic coatings, porcelain enamels and glazes. Also, the compound is used as an acid catalyst in organic synthesis and to prepare several other boron compounds. 

The synthesis of llZ-retinal required the boronic-partner, which was prepared from 2-butyn-l-ol by addition of the tributylstannyl cuprate (83%), followed by protection of the alcohol with tBuMe2SiCl (TBDMSC1) (93%). The tributylstannyl group was substituted with boronic acid in three steps lithiation, quenching alkenyllithium with triisopropyl boronate and hydrolysis to the boronic acid. The Suzuki coupling of the C 6 tetraene with the boronic compound was carried out in THF at room temperature, in the presence of a catalytic amount of... 

Allylpotassium derivatives exist in two stereoisomeric (endo or exo) forms.239,240 Although the endo isomer is more stable, the equilibration is slow enough to allow the synthesis of stereoisomeric heterosubstituted derivatives [Eqs. (10.42) and (10.43)]. On the other hand, even the E-alkenes after appropriate equilibration can be transformed to Z-boron compounds 10 ... 

The electrophilic addition of hydrogen-bearing boranes to alkenes (hydroboration), now recognized as a vital component of organic synthesis, is covered in Chapter 1.7 of this volume. The boron compounds that do fall under the realm of this chapter are boron bromides. Suzuki and coworkers have demonstrated... 

For the last four decades, there has been an exponential increase in the synthesis and usage of a number of organic and inorganic boron compounds in industry and academia. Due to the explosive growth of heterocyclic boron-containing compounds, this topic is covered as a separate chapter here. Previously, the subject of this chapter was covered in a subsection of Chapter 4.24 in CHEC-II(1996) (Sections 4.24.1.3.6 and 4.24.1.3.7). This chapter covers as much literature as possible, but the space restraints did not permit a comprehensive coverage of all literature. 

Another common synthesis of cyclic boron compounds involves transesterification. For example, the chiral allyl boronates 155 can be synthesized via the reaction of dioxaborolane 329 with dialkyl tartrate 330 in high yield. The transacetalization affords an attractive alternative to the formation of these chiral boronates, which are otherwise difficult to prepare (Equation 13). 

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