Boronic pharmaceutical applications

Several complexes have been tested for potential pharmaceutical applications and some of them have been introduced into practice.84,126 Isolation of antibiotics of boron complex type (Section 24.3.3.2) and results obtained with carboxyborane complexes that are analogues of amino acids (Section 24.2.2) are likely to stimulate further studies. Quite a few boron complexes have found application in 10B neutron capture therapy based on the 10B(n, a)7Li nuclear reaction.84,126,172... 

Once the stability problem with (a-aminoalkyl)boronic esters was understood, several research groups began searching for possible pharmaceutical applications. These studies are covered in Chapter 13. 

These products include fiberglass, borosilicate glass, fire retardants, fertilizer, enamels and ceramic glazes, soaps and detergents, cosmetics and pharmaceuticals, and pesticides. Boron also has wood preservation, metallurgical, and nuclear (neutron absorption) applications. 

Typical examples of analytical applications of gas generation MECA detection include the determination of ammonium in fertiHzers, fluorine in toothpaste, boron in steel samples, and thiamine and cephalosporins in pharmaceutical preparations. 

Boron as a dopant allows silicon and carbon materials to significantly change their conductivity and thereby open up applications in particular with boron-doped diamond (sp -carbon) as mechanically and chemically robust electrode material. The range of beneficial effects of boron in boron-doped diamond as electrode materiaP has been reported. Bio-electrochemical processes like the oxidation of NADH are possible with diamond dominating the interfacial chemistry. The sp nature of the diamond allows adsorption processes to be modified, and electrode erosion to be minimised, with electroanalytical application even under extreme conditions, for example in the presence of ultrasound and for pharmaceutical components. Boron surface functional groups have been reported to be crucial for electron transfer, for example, during glucose oxidation. ... 

The industrial application of catalytic direct amide formation is still little explored and the eurrent proeesses are still unoptimised. Moreover, due to the high tolerance to water, aeids or bases, boron-based catalysts could be considered one of the most potentially interesting areas of research in the arena of direct amidation used in pharmaceuticals and fine chemicals. Clear steps have been followed so far by the scientific community in this direction for amide transformation, especially with boron-based eatalysts, and a renaissance in this area has already been triggered. 

The polyhedral boranes described above are available from commercial sources however, they are all very expensive due to the absence of large-scale industrial production and could find practical applications only in some exclusive areas where no alternative exists. The use of polyhedral boranes in some of the fields described below obviously has no alternative, in other fields the price of modern pharmaceuticals is comparable with price of boron hydride derivatives, and in some cases the boron hydride price is negligible in comparison with the price of drug as a whole. 

Sodium borohydride, NaBH4, contains 10.7 wt% H2. It is currently the most commercially important of the boron hydride compounds. Several thousand tons of this material are manufactured annually for use as a reducing agent in various industries applications, including the manufacture of specialty chemicals, pharmaceuticals, paper, and in waste water treatment. Its use in hydrogen storage is also the oldest and most extensively developed among the metal borohydrides. 

In Prof. Garti s opinion, employing multiple emulsions should not be restricted to pharmaceuticals, nutraceuticals, and cosmetics. He hopes that other promising and exciting applications will be available in near future. The microencapsulation of fine boron particles in W/OAV multiple emulsions may serve as such a feasible example. ... 

A recent example of the application of solid phase Suzuki reactions to the synthesis of pharmaceutically important biaryl compounds was shown by Nielsen et aL [115]. A range of aryl-substituted pyrroloisoquinolines were synthesized from biarylalanine precursors in high purity (Scheme 39). This involved a Suzuki coupling of sohd-supported iodophenylalanine derivatives containing a masked aldehyde to various boronic acids, followed by hberation of the aldehyde, TFA-mediated intramolecular Pictet-Spengler reaction, and cleavage. 

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