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Miyaura boration reaction

Iron-catalyzed Suzuki-Miyaura coupling reactions were also reported by Nakamura and colleagues (entry 27) [67]. Alkyl halides 1 and mixed pinacol aryl(butyl)borates, generated in situ from arylboronates and butyllithium, were used as the reagents and 10 mol% of the iron complexes 16a or 16b as the catalysts. The addition of 20 mol% of MgBr2 was essential for the success of the reaction. Products 3 were isolated in 65-99% yield. The methodology tolerates ester and nitrile functions. The reaction starts probably by initial boron-iron transmetalation to generate a diaryliron(II) complex. [Pg.199]

A novel macrocyclization reaction was developed based on a domino Miyaura boration intramolecular Suzuki crosscoupling sequence in the laboratory of J. Zhu. " This strategy was applied in the synthesis of biaryl-containing macrocycles. The diiodide substrate was dissolved in degassed DMSO, and then the catalyst and the base were added. Successful macrocyclization required extensive experimentation, and the authors determined that the concentration and the nature of the base were the two most important factors. Interestingly, potassium carbonate is not suitable as a base in the Miyaura boration, since it tends to give biaryl by-products, but in this particular macrocyclization reaction it proved to be completely ineffective because the reaction failed to take place. [Pg.297]

The palladium-catalyzed coupling of boronic acids (as well as other boron derivatives) with aryl and vinyl halides and psendohalides is known as the Suzuki or Suzuki-Miyaura reaction. Because boron is nontoxic, this reaction has been used in pharmaceutical syntheses. In addition, hydroboration or borate substitution allows for the synthesis of virtually any desired coupling partner. For these reasons, as well as the high yields and functional group compatibility, the Suzuki reaction is the first reaction to consider for carrying out a cross coupling. Representative substrates and catalysts are shown in Scheme 17. The various bases are used to generate four-coordinate boron ate complexes that are more reactive in transmetalation. [Pg.3563]

In the strategy described in Fig. 16b, the linear precursor is not built on the polymer, but the final cyclization reaction using the Suzuki-Miyaura coupling takes place on a polymer. The aryl boronic acid is captured on a Dowex ammonium hydroxide resin, leading to the polymer ionically bonded borate, which is subsequently treated in the appropriate conditions to give the final macrocyle. This methodology is called resin capture-release.. ... [Pg.838]

Although the SM reactions of haloferrocenes proceed rather slow, they are clean and chemoselective, providing the production of arylferrocenes which would be hardly accessible by other strategies. Several papers regarding improved and alternative technics for performing the Suzuki-Miyaura reactions have been published. A useful procedure involves transmetallation of (half amount) simple aryl halides with only 0.5 eq. of -BuLi, followed by quenching the resulted aryllithium reagent with trimethyl borate [88], Thus obtained arylboronic ester is coupled under the standard SM conditions method A) with an excess of parent aryl halide to furnish the symmetrical biaryl in fair yields. For example, 2-bromoanisole (218) was coupled by this way to afford 2,2 -dimethoxybiphenyl (92) in 56% yield [88], Scheme 36. [Pg.170]

During studies on rhodium-catalyzed Suzuki-Miyaura cross-coupling reactions, Miura and coworkers reported more recently on the use of less-toxic tetraphenyl-borate 6 for the direct arylation of imines (Scheme 9.4) [16]. Unfortunately, rather low yields of mono- and di-arylated products were obtained, this being due to a reduction of the starting material via a sequence consisting of a rhodium hydride addition and subsequent protonation. The reduction of the imine is mandatory for the regeneration of a rhodium chloride species, and thereby for catalytic turnover. [Pg.313]

Other activated and stable borates were developed over the past few years for use in the Suzuki-Miyaura cross-coupling reaction. Whitehead and coworkers [88] have developed activated sodium trihydroxyborate salts through the treatment of boronic... [Pg.99]

Mechanistic knowledge of the Suzuki-Miyaura reaction is far from complete [22d, 23], Although a base is obligatory and phenylboronic acids are known to form borates at high pH, evidence is not available for an RB(OH)3 intermediate. Especially intriguing, compared with other cross-coupling processes, is the unknown step. [Pg.1071]

Traditionally, arylboronic acids have been used in the Suzuki-Miyaura reaction, but considering the fact that arylboronic acids do not participate in the transmetallation process, different types of borate complexes have been devised. In 2006, Cammidge s group [139a] reported the application... [Pg.62]

Buchwald and co-authors reported synthesis of biaryls by a lithiation/ borylation/Suzuki-Miyaura cross coupling sequence in continuous flow [53]. Aryl bromides could be lithiated at room temperature with 2 s-10 min residence time by mixing with n-BuLi, which then reacted with B(OiPr)3 at room temperature with 1 min residence time to afford aryl borates, ArB(OiPr)3Li. The reactor was sonicated to avoid blocking by precipitated ArB(OiPr)3Li. The reaction mixture was then mixed with Pd catalyst/THF solution and reacted at 60 °C (4—10 min residence time) to give biaryls in good yields. For example, 2-fluoro-4 -methoxy-[l,l -biphenyl]-4-carbonitrile was obtained in 94% yield (4 min residence time) (Scheme 5.38). [Pg.119]

In a variation of the Suzuki-Miyaura reaction, trifluorostyrene derivatives, such as (69), have been prepared by palladium-catalysed reaction of aryl bromides with lithium trimethoxy(trifluorovinyl) borate. DFT calculations have been reported explaining... [Pg.227]

Alkynyl boronic acid derivatives were not used earlier in Suzuki couplings. An effective Suzuki-Miyaura reaction between alkynyl ate complexes (alkynyltrialk-oxy borate complexes) has been reported by Colobert [112] Oh [113]. 1-Alkynyl(trii-sopropoxy) borates (137) were prepared by borylation of the corresponding alkynyl lithium species. These stable borate complexes were subsequently used in Suzuki coupling leading to products of type 138 (Scheme 3.74). [Pg.88]


See other pages where Miyaura boration reaction is mentioned: [Pg.436]    [Pg.507]    [Pg.700]    [Pg.436]    [Pg.266]    [Pg.239]    [Pg.436]    [Pg.507]    [Pg.700]    [Pg.436]    [Pg.266]    [Pg.239]    [Pg.296]    [Pg.101]    [Pg.742]    [Pg.143]    [Pg.25]    [Pg.210]    [Pg.210]    [Pg.19]    [Pg.526]    [Pg.183]    [Pg.455]    [Pg.68]    [Pg.100]    [Pg.106]    [Pg.107]    [Pg.113]    [Pg.819]    [Pg.768]    [Pg.148]    [Pg.64]    [Pg.183]    [Pg.759]    [Pg.192]   
See also in sourсe #XX -- [ Pg.436 ]

See also in sourсe #XX -- [ Pg.436 ]

See also in sourсe #XX -- [ Pg.266 ]

See also in sourсe #XX -- [ Pg.239 ]




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