Suzuki reaction typical

Attempted intermolecular cross-benzoin reactions typically generate a thermodynamically controlled mixture of products [50], although several groups including Enders [51], Suzuki [52] and You [53] have utilised catalysts 116-118 for the intramolecular crossed benzoin of keto-aldehydes (Scheme 12.22). 

The palladium nanoparticle is prepared from the reaction of the stabilizer, 4,4 -bis(perfluorooctyl)dibenzylideneacetone with palladium(II) chloride. The average size of the nanoparticle varied according the ratio of PdCF to the stabilizer, but was typically around 4 or 5 nm. The initial yield observed in the Suzuki coupling reaction was 90%, but decreased to 78% after five consecutive runs. Fluorous boronates (alternative precursors in Suzuki reactions), have also been developed for use in fluorous biphasic processes [12], A generic structure of a fluorous boronate is shown in Figure 10.2. 

Chemists working to develop new bioactive compounds try to be alert for new stable heterocycle platforms, but they can easily overlook some of the more, shall we say, exotic ones. When one thinks about the utility of boron in heterocyclic chemistry, the Suzuki cross-coupling reaction typically first comes to mind. In this valuable synthetic reaction <95CRV2457>, a boronic acid group is discarded under basic conditions during a Pd-catalyzed C-C bond formation. There are exceptions, of course, but few chemists appreciate that boron is an element that can be valuable to retain in a molecule so that its unique properties can be utilized. 

Under standard Suzuki reaction conditions, the coupling of tricarbonyl[//6-(diphenylphos-phino)benzene] chromium]0) with typical arylboronic acids has been achieved, giving biaryl complexes in high yield (Eq. (18)). This type of reaction sequence serves to generate product complexes that are not available by other means [41]. 

The Suzuki reaction is a palladium-catalyzed coupling of an organic halide (R X) with an organoborane (RBY2) to form a product (R-R ) with a new C-C bond. Pd(PPh3)4 is the typical palladium catalyst, and the reaction is carried out in the presence of a base such as NaOH or NaOCH2CH3. 

Useful solvents for the formation of the boronate ester include THF, 2-Methyltetrahydro-furan, 1,4-dioxane, dimethyIformamide, and dimethylsulfoxide (DMSO). Pd(dppf)Cl2 and potassium acetate are typically used for the formation of the pinacolatoboronic ester. Often after workup, the crude boronate is used for the subsequent Suzuki reaction. As can be seen with the example below, various functional groups tolerate this transformation. 

A different example of triphasic catalysis for the Heck, Stille and Suzuki reactions relied on a three-phase microemulsion/sol-gel transport system. Gelation of an z-octyl(triethoxy)silane, tetramethoxysilane and Pd(OAc)2 mixture in a H2O/CH2CI2 system led to a hydrophobicitized sol-gel matrix that entrapped a phosphine-free Pd(ii) precatalyst. The immobilized precatalyst was added to a preformed microemulsion obtained by mixing the hydrophobic components of a cross coupling reaction with water, sodium dodecyl sulfate and a co-surfactant, typically zz-propanol or butanol. This immobilized palladium catalyst was leach proof and easily recyclable. 

Heck and Stille coupling reactions, also allowing reactions to be conducted under solvent-free conditions. The synergic effect of polymer 96 and TSIL not only reflected an increased stability during storage but also an enhanced activity during catalysis. Scheme 1.62 shows a typical Suzuki reaction occurring in an aqueous biphasic medium. 

The air-stable phosphine-borane la was evaluated in the Pd-catalyzed Suzuki-Miyaura reaction. Typically, 4-bromoanisole and phenyl boronic acid were efficiently coupled using 1 mol% of PdCOAc) and 2 mol% of ligand la (Scheme 6). The BMes moiety is compatible with the cross-coupling and it actually improves catalytic activity (under the same conditions, PPh gives a notably lower yield). Interestingly, a catalytically competent Pd(0) complex 39 was isolated and fully characterized. The phosphine-borane adopts a new coordination mode besides phosphorus, the Pd center is coordinated by one of the Mes groups at B interaction). 

Uemura has shown that aryl chlorides which are T -bound to Cr(CO)3 are remarkably reactive coupling partners in Suzuki reactions [23, 24]. Even in the presence of the electron-donating, deactivating ortho-methoxy substituent, the aryl chloride couples with an arylboronic acid (Equation 2.13). Furthermore, no homo-coupled 4 -bromobiphenylboronic acid is observed, establishing that highly selective activation of a C—Cl bond is occurring in the presence of a typically more reactive C—Br bond. 

The Suzuki reaction is a powerful carbon-carbon bond-forming reaction method for the rapid introduction of diverse substituent onto an aromatic ring. Substituted arylacetic acids represent an important class of cyclooxygenase inhibitors. These inhibitors that are built on the phenylacetic acid core, typically incorporating three elements of variability an a-alkyl group, R alkyl, aryl or heteroaryl substitution on the phenyl ring, R and acid or amide functionality (Scheme 31.5). To synthesize this variety of molecules requires successful construction of a combinatorial library of a class of compounds and that depends... 

The Suzuki reaction is a member of a class of transformations that are typically referred to as cross-coupling reactions,which involve the... 

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