Arylboron compounds

Arylboron compounds as acid catalysts in transformations of heterocycles 99EJ0527. 

For the synthesis of a suitable arylboron compound, usually an aryl halide is converted to an aryllithium or aryl Grignard derivative, and then reacted with a trialkoxyborane to yield an arylboronic ester, e.g. the phenylboronic acid diisopropyl ester 13 from bromobenzene 11 ... 

The Suzuki reaction97 allows tire coupling of two aromatic rings by reaction of an arylboronic compound with a iodo or bromo aryl derivative. The tetrakis (U iphenylphosphine) Pd is the catalyst working in the basic medium. This reaction was recently used98 in aqueous media for the preparation of different isomers of diphenyldicarboxylic acids (Fig. 5.21) but also for the synthesis of soluble rodlike polyimides99 by coupling the 3,6-diphenyl- V, V,-bis(4-bromo-... 

Recently, arylboron compounds have been developed as Lewis acids. For example, in the presence of a catalytic amount of B(C6F5)3, several carbon-carbon bond-forming reactions proceed smoothly (Scheme 64j.294-296... 

Microreview on arylboron compounds in organic synthesis Ishihara K, Yamamoto H (1999) Eur J Org Chem 527... 

Arylalkenes are accessible not only by way of an arylation of alkenylboron compounds (Figure 16.18) but also via an alkenylation of arylboron compounds. Figure 16.19 exemplifies... 

Akira Suzuki, from Kurashiki University, Japan, is one of the great names of arene chemistry due to his outstanding reaction that bears his name. As expected, his chapter (No. 3) deals with the Suzuki reaction with arylboron compounds and its synthetic applications in arene chemistry. The Suzuki reaction is now becoming all the more important as requirements for organic synthesis will necessarily have to take ecological aspects ( green chemistry ) into account and use of a number of toxic metals is phased out. 

The Suzuki Reaction with Arylboron Compounds in Arene Chemistry... 

Coupling of Arylboron Compounds Bearing Sterically Bulky or Electron-Withdrawing Substituents... 

Stereodefined enol acetates of ketones can readily be synthesized by palladium-catalyzed cross-coupling reactions of arylboron compounds with enol acetates of a-bromo ketones (Eq. (70)) [113]. 

Arylalkenes are accessible not only by way of an arylation of alkenylboron compounds (example in Figure 13.14) but also via an alkenylation of arylboron compounds. Figure 13.15 exemplifies this for a Pd-catalyzed reaction of an arylboronic acid with iodoalkenes with widely variable substitution patterns. The addition of KOH increases the reactivity of the arylboronic acid in this coupling and in similar ones. The base converts the boronic acid into a negatively charged boronate ion A. This ion A is transmetallated faster than the neutral boronic acid by the Pd(II) intermediate the boronate ion is a superior nucleophile and replaces the iodide ion in the Pd(II) complex particularly fast. 

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