Suzuki-Miyaura reaction trifluoroborates

Suzuki-Miyaura Reactions from Trifluoroborates The convenient use of stable RBFj" as an alternative to RB(OH)2 was developed in 1999 by Genet [63a] and Molander [63b] (Scheme 19.45). 

Few literature data allow a clear-cut comparison between different arylboronic esters under identical reaction conditions (Cu, Ni, Ru, Pd, ). Heise and coworkers tested the reactivity in Suzuki-Miyaura reactions of the three cyclic esters Bpin, Bhg, Bnpg under the same conditions. This reactivity clearly increases with decreasing steric hindrance (Scheme 3.35). For Ni-catalyzed Suzuki-Miyaura couplings also, the relative efficiencies of boronic esters of pinaeol and neopentylglycol, boronic acid and trifluoroborates were compared in a dedicated study. Parallel and competition experiments... 

Scheme 2.25 Suzuki-Miyaura cross-coupling reactions of heteroaromatic trifluoroborates.

Recent innovations have involved the use of trifluoroborate [29], tetraarylborate [30], and trihydroxyborate [31] salts, some originating from DoM reactions, as coupling partners in the Suzuki-Miyaura cross-couplings. 

Another solution is to employ trifluoroborate salts 2.215, which can be prepared from the boronic acid by treatment with potassium hydrogen fluoride (Scheme 2.74). They can also be prepared from alkyl bo-ranes in a similar way (Scheme 2.75). These stable salts can be efficiently employed in Suzuki coupling reactions (Scheme 2.T6)P One application is in the synthesis of the unusual amino acid, trityrosine 2J26 (Scheme 2.77). In this synthesis an aryl diiodide 2.222 was coupled with a trifluoroborate salt 2.224 that had been formed by Miyaura borylation of iodide 2.223 followed by KHF2 treatment. Global debenzylation of coupling product 2.225 gave the product 2.226. Another example of the use of a trifluoroborate salt can be found in Scheme 2.88. 

The example below highlights the question of whether parallel or miero-wave chemistry (MW) would have a significant effect on MI in the medieinal chemistiy environment. As an example, comparison of a multimode MW and single mode MW have been used. The reaction studied was a Suzuki-Miyaura reaetion with the aim to compare different catalysts and boron-sources like boronie acid, boronic acid ester and trifluoroborates (Figure 9.10). ... 

Molander, G. A., Bernard , C. R. 2002. Suzuki-Miyaura cross-coupling reactions of potassium alkenyl-trifluoroborates. J. Org. Chem. 67 8424—8429. 

Typically, boronic acids/boronates, dialkylboranes, or trifluoroborates can all be used for Suzuki-Miyaura cross-coupling reaction. The following section details several protocols reported in the literature for the synthesis of these boron congeners. 

In 2008, Ackerman and co-workers applied these methods for the synthesis of fully decorated triazoles [259]. Their studies revealed that a single copper system based on Cul and DMEDA L26 ligand was able to catalyze in a one-pot procedure the arylation of sodium azide and the subsequent in situ arylation in position 5 of the resulting triazole, via a sustainable C-H functionalization. Based on the same type of strategy, various organo-[l,2,3]-triazol-l-aryl-trifluoroborates were recently prepared by Ham and subsequently used as substrates in Suzuki-Miyaura cross-coupling reactions [260],... 

Synthesis of Functionalized Trifluoroborates and their Palladium-catalyzed Suzuki-Miyaura Cross-coupling Reactions... 

Preparation and B-alkyl-Suzuki-Miyaura Cross-coupling Reactions of Functionalized Alkyl Trifluoroborates... 

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