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Alcohols with aryl boronic acids

The groups of Veith, Braunstein, and Bedford reported the use of Pluronic P123 (a polymeric material) as template for the pore structure [52]. Hydrolysis and co-condensation of l,3-bis(3-trimethoxysilylpropyl)imidazolium chloride and tetramethoxysilane in the presence of these vesicles under acidic conditions, followed by immobilization of palladium precursors, resulted in a highly ordered mesoporous material with a two-dimensional hexagonal pore structure with palladium nanoparticles inside the pores. These palladium particles have been successfully utilized for the Suzuki cross-coupling of aryUiaUdes with aryl-boronic acids in water, as well as the aerobic oxidation of alcohols under oxygen and air atmospheres as shown in Scheme 4.10 [53]. [Pg.90]

In 2006, the group of Artok showed that 5-aryl-2(5H)-furanones could be prepared in moderate to good yields by a rhodium-catalyzed carbonylative arylation of internal alkynes with aryl boronic acids (Scheme 1.9a) [22]. a,P-Unsaturated ketones (chal-cone derivatives) were formed as the major product when some TFA (trifluoroacetic acid) was added under the same reaction conditions [23a]. By varying the catalytic system, indanones could be produced as the main product [23b]. The chemical behavior of terminal alkynes is different, and either a,P-unsaturated ketones or furans starting from propargylic alcohols can be achieved (Scheme 1.9b) [24, 25]. In the case of vinyl ketones, 1,4-diketones were obtained by rhodium-catalyzed coupling of arylboronic acids in the presence of 20-40 bar of CO [26]. In 2007, Chatani demonstrated that indenones could be accessed by a carbonylative rhodium-catalyzed cyclization of alkynes with 2-bromophenylboronic adds (Scheme 1.9c) [27]. Here, the key intermediate is a vinylrhodium(I) spedes that is formed by transmetaUation of RhCl with 2-bromophenylboronic acid followed by insertion of... [Pg.13]

Interestingly, in contrast to the numerous intramolecular couplings between alcohols and aryl boronic acids [lb], there are no reports of intramolecular copper-catalyzed N—H bond arylahons with boronic acids. [Pg.147]

FIGURE 21. Numerous macrocycles based on salicylideneamino alcohols, arising from (a and b) aliphatic and (c and d) aromatic amines, interacting with aryl boronic acids have been identified, (e) Analogous semianhydride bridged structures have also been observed. [Pg.277]

In 2000, Guy reported the stoichiometric coupling of alkane thiols and arylboronic acids, which was initially thought to be mediated by Cu(ll) [71]. Liebeskind proposed that the reaction was more likely catalyzed by Cu(l), generated by oxidation of the alkane thiols into dialkyl disulfides. Based on this hypothesis, Liebeskind predicted that disulfides and disulfide equivalents should be effective reagents for thioether formation [34]. This process would constitute a modification of the Chan-Evans-Lam, which involves the coupling of arylboronic acids and amines or alcohols in the presence of tertiary amine bases, generating aryl amines and ethers, respectively. Indeed, the coupling of diphenyl disulfide with phenyl boronic acid would yield diphenyl sulfide. [Pg.44]

The same ligand allowed the cross-coupling of various boronic acids (aryl, alkenyl, alkyl) with alkyl bromides in the system (Pd(OAc)2/PMe Bu2, BuOK. amyl alcohol, r.t.).411... [Pg.347]

Boronic acids can be reversibly esterified with resin-bound diols (Figure 3.15). The resulting boronic esters are stable under the standard conditions of amide bond formation, but can be cleaved by treatment with water under acidic or neutral conditions to yield boronic acids. Treatment of the resin-bound boronic esters with alcohols yields the corresponding boronic esters [197]. Resin-bound boronic esters are suitable intermediates for the Suzuki reaction [198], Treatment with H202 leads to the formation of alcohols (Entry 8, Table 3.36), while treatment of resin-bound aryl boronates with silver ammonium nitrate leads to the conversion of the C-B bond into a C-H bond (Entry 14, Table 3.46). [Pg.57]

Some other important aspects of boric acid chemistry are summarized in Fig. 5-26. Among these is the formation of borate esters [B(OR)3, R = alkyl or aryl], usually obtained as colorless liquids, on treatment with alcohols and H2S04. The vast literature on these compounds falls generally within the purview of organic chemistry, and will not be developed here however, it will be noted that a well-known qualitative test for boron involves treatment of the sample with methanol to form B(OMe)3, which produces a bright green color in a Bunsen burner flame. A major early discovery in this area was the synthesis of boronic acids by E. Frankland in 1862, via partial oxidation of trialkylboranes, with subsequent hydrolysis of the ester ... [Pg.172]

Asymmetric hydrogenation of bromo-substituted aromatic a-enamides 14 affords the corresponding bromo-amino acid derivatives 15, which subsequently is subjected to Pd-catalyzed cross-coupling with aryl and vinyl boronic acids. In addition to diverse phenylalanine derivatives 16, a broad array of other novel aromatic and heterocyclic amino acids have been produced rapidly from a small number of bromo-functionalized intermediates [24], This same two-step process may be applied to the production of many other classes of aromatic and heterocyclic chiral building blocks, such as arylalkylamines, amino alcohols, diamines, and directly on peptides as well. [Pg.349]


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See also in sourсe #XX -- [ Pg.932 ]




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Aryl acid

Aryl alcohol

Aryl boronate

Aryl boronates

Aryl-borons

Boron aryls

Boronic acids, arylation

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