Suzuki-type cross-coupling reactions

R = Bu, CH(Oa>2, CH(OAc)CHj Figure 20 Suzuki-type cross coupling reaction. 

Chen, H. Deng, M.-Z. A novel Suzuki-type cross-coupling reaction of cyclopropylboronic esters with benzyl bromides./. Chem. Soc. Perkin Trans. 1 2000, 1609-1613. 

Bazan and coworkers also prepared anthracene-substituted swivel cruciforms 33 with binaphthyl cores [44, 45]. They attached the anthracene units to the binaphthyl in the 6,6 -positions by a Suzuki-type cross-coupling reaction (Scheme 3.15). Based on the aforementioned findings that the alkoxy chain length influences the solid-state properties of these types of materials, they produced two de-... 

One of the challenges in the Suzuki-type cross-coupling is to extend this reaction from electron-rich aryl iodides, bromides, and triflates to less reactive aryl sulfonates and aryl chlorides, which show poor reactivity in terms of oxidative addition in the catalytic cycle. Aryl mesylates, benzenesulfonates, and tosylates are much less expensive than triflates, and are unreactive toward palladium catalysts. The Ni(0)-catalyzed Suzuki-type cross-coupling reaction of aryl sulfonates, including mesylates, with arylboronic acids in the presence of K3P04 has been reported [123]. 

Therefore stereoselective methods have been investigated and developed. An alternative entry to the Z-isomer of Combretastatin A-4 was based on the Z-selective Lindlar-type semihydrogenation of an appropriate alkyne precursor, readily assembled by a Suzuki-type cross-coupling reaction (Scheme 2) [9]. 

Ru-catalyzed Suzuki-type cross-coupling reactions of aniline derivatives and organoboronates have been achieved via unreactive aryl C—N bond cleavage (Equation 11.48) [109]. The proposed reaction pathway is a sequence of oxidative addition of an unreactive aryl C—N bond to the late transition metal complex, followed by transmetalation between the Ru-NR2 species and organoboronates, and reductive elimination. 

As seen with pyridazines, palladium catalyzed coupling reactions were also frequently applied in the phthalazine field. For example, commercially available 1,4-dichlorophthalazine 185 was aminated to give 186 in good yield by aromatic nucleophilic substitution with A -methylpiperazine <01S699>. Then, 186 was coupled with various substituted arylboronic acids to obtain 187 by Suzuki-type cross-coupling reactions. Best results were obtained with electron-donating substituents on the arylboronic acid. 

Most recently, the anti-HIV alkaloids michellamines A and B have snccessfully been synthesized by a double Suzuki-type cross-coupling reaction between a binaphthalene ditriflate and an isoquinoUneboronic acid (Scheme... 

Geerts et al. recently synthesized liquid crystalline oligothiophenes 2.61 (n = 1,2) (Chart 1.13) comprising two incompatible peripheral substituents, such as alkyl and perfluoroalkyl groups, which were attached to the core by Suzuki-type cross-coupling reactions [129]. Compound 2.61 (n = 1) formed a smectic A mesophase on cooling from 220 °C (isotropic liquid) to 200 °C, whereas 2.61 (n = 2) formed an insoluble material and no phase transitions were observed before decomposition at 250 °C. 

Reaction of the anion 3 with trialkyl boron compounds gives adducts which eliminate the toluenesulfonate group in a 1,2-alkyl shift (eq 3). The resultant vinyl boron compounds are capable of undergoing Suzuki-type cross-coupling reactions. Using this method, Ichikawa et al. were able to convert 3 into functionalized aryl adducts which were then cyclized in a 5-endo fashion to give monofluorinated adducts. ... 

Recently, the anti-HIV alkaloids, michellamine A (15) and B (16) have been synthesized. The tetraaryl skeleton of the michellamines was constructed by fornmtion, first, of the inner (nonstereogenic) biaryl axis and subsequently of the two other (stereogenic) axes by using a double Suzuki-type cross-coupling reaction betwe i the dinaphtalene ditriflate (13) and isoquinolineboronic acid (14) (Fig 2) (12). 

Trimethylsilylation of Vinylboronates. Vinylboronate esters react with vinyltrimethylsilane under ruthenium catalysis to give the I trimethylsilyl-l-boronylethylene (eq 34). Such a species could be used in Suzuki-type cross coupling reactions to prepare various a-substituted vinyltrimethylsilanes. ... 

Radius and co-workers next reported examples of Suzuki-type cross-coupling reactions of perfluorinated arenas i.e. octafluorotoluene or per-fluorobiphenyl) (Equation (10.16)). Again, [(IiPr)4Ni2(COD)] was used to activate the C-F bond (see Section 10.4.2). 

A drawback of the Heck-type reaction is that it is not strictly regioselective [119]. Depending on the substituents >1% of 1,1-diarylation is observed. Soluble 2,5-dialkoxy-PPVs 63 or 2-phenyl-PPV PPPV 93, without 1,1-diarylated moieties, were synthesized by Heitz et al. in a Suzuki-type cross coupling of substituted 1,4-phenylenediboronic acids and fran5-l,2-dibromoethylene, catalyzed by Pd(0) compounds [120]. However, about 3% of biaryl defect structures are observed in the coupling products (M up to 12,000), resulting from homocoupling of boronic acid functions. 

Hartwig-Buchwald, Suzuki, and Stille type cross-coupling reactions with key intermediate 46 led to a wide range of substituted sulfoximines such as 47-49 [37]. In order to demonstrate the synthetic utility of the resulting products, pseudo tripeptide 50 was prepared from a related intermediate. 

For aromatic C— F bonds, the Suzuki-type cross-coupling of perfluorinated arenes, such as octafluorotoluene and perfluorobiphenyl, in the presence of nickel catalysts has been developed (Equation 11.47) [108]. In these reactions, triethylamine is used as a base, whereas stronger inorganic bases are typically used in Suzuki coupling reactions. 

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