Arylboronic acid esters arylation

Table 7. Aryl Fluorides by Reaction of Arylboronic Acid Esters with Cesium Fluoroxysulfate...

Entry Arylboronic Acid Ester 17 R Aryl Fluoride 16 Yield (%) Ref... 

Simiraly, alkynones undergo arylative cyclization with arylboronic acids in the presence of a rhodium catalyst (Equation (49)).400 When acetylenic /3-keto esters are employed as shown in Equation (50), arylative cyclization (formation of cyclobutanols) and subsequent, facile acid-catalyzed bond cleavage take place to give <5-keto esters.401 Ring expansions of cyclic [3-keto esters are also possible according to this reaction. 

Trialkylaryltin derivatives 30 are converted into fluoro-substituted derivatives 31. 37-38 (4-Mcth-oxyphenyl)trimethylsilane (32) in acetonitrile gives 4-fluoroanisole and (3-fluoro-4-meth-oxyphenyl)trimethylsilane in the ratio 1 2. A -Methyldiethanol esters of arylboronic acids 33 (l-aryl-5-methyl-2,8-dioxa-5-azonia-l-boranuidabicyclo[3.3.0]octanes) are converted into tluoroaromatic compounds with cesium fluoroxysulfate in acetonitrile in the presence of 1,3-dinitrobenzene at room temperature.39-40 Regiospecific synthesis of 2-fluoro-3-0-methyles-trone in 27 % yield occurs upon fluorination of the corresponding arylboronic acid with cesium fluoroxysulfate.41... 

Aryl halides of many different types, including simple unsubstituted halides, may be conveniently converted into phenols by an indirect route involving the preparation of an arylboronic acid and its subsequent oxidation with hydrogen peroxide. The arylboronic acid (3) is normally prepared by reaction of the corresponding arylmagnesium halide with a borate ester (typically tributyl borate) at between —60 and — 80 °C, to yield the dialkyl boronate ester (2) which is then hydrolysed to the arylboronic acid (3). The latter may be isolated, purified and then oxidised with hydrogen peroxide as described in the preparation of m-cresol (Expt 6.101). Alternatively the crude reaction mixture from the preparation of (3) may be treated directly with hydrogen peroxide.36... 

Arylboronic acids are also efficient reagents for the arylation of 1-alkenyl halides and tri-flates. The first such cross-coupling reactions between arylboronic acids or esters and 1-alkenyl electrophiles were performed in the presence of a palladium catalyst and a base... 

A boron-iodine exchange between vinyl- and arylboronic acids or esters and hypervalent phenyliodanes gave vinyl-aquation (117)) and aryl(phenyl)iodonium salts (Equation (118)) with complete retention of configuration.556,557... 

Aryl fluorides 1635 -37 and 1936 are prepared by ipso substitution of arylboronic acids or esters with cesium fluoroxysulfate (Tables 6 and 7).35-37... 

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