Aryl coupling with pinacolborane

Suzuki and Stille couplings. For coupling of aryl chlorides with arylboronic acids the catalytic system contains (CyjPjjPdClj, CsF in NMP. co-Arylalkanoic acids are prepared by coupling of aryl halides with carboxylic esters bearing a 9-BBN substituent at the other terminus, and saponification. A biaryl synthesis from two different aryl halides is accomplished with in situ boronate formation which depends on the (dppfjPdClj catalyst. For access to aryl boronates either the coupling of aryl triflates with bis(pinacolato)diboron" or that of aryl iodides with pinacolborane may be employed. 

Reaction of (2,5-diphenylphospholyl)-2-methylpyridine with (PdC D) COD) afforded a complex which catalyzed the cross-coupling between pinacolborane and iodoaromatics to afford corresponding arylboronic esters with TONs up to 100 x 10 and with TONs up to 90 X 10 in the case of aryl bromide [195]. 

Recently, the hydroboration of I -alkynylphosphonates with pinacolborane has been reported. However, the vinylphosphonoboronatcs so obtained are difficult to isolate, and they are immediately subjected to Suzuki coupling reactions with aryl iodides. Similarly, hydrophenylation of diethyl... 

Pinacolborane is a unique boron nucleophile for a similar coupling reaction with aryl iodides or bromides (Eq. 14). It is interesting that... 

Recently, a novel coupling reaction, based on the used of pinacolborane as an efficient reagent for the electrochemical functionalization of aryl halides in the presence of an Mg anode afforded arylboronic pinacol esters [2]. However, this reaction presents some limitations low faradic efficiencies with aryl chlorides,... 

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