Carbon Suzuki-Miyaura coupling

Suzuki-Miyaura coupling has also been conducted in a capillary reactor (400 i.m inner diameter).A commercial-scale continuous flow system consisting of a 14.5 cm x 25.4 mm column packed with Pd catalyst has also been developed. In this case, supercritical carbon dioxide is used as... 

For instance, the Suzuki-Miyaura coupling of bromofuranone 25 with phenylboronic acid 26 in acetonitrile with sodium carbonate resulted in complete decomposition at 90°C, whereas in toluene with potassium carbonate, a 40% yield of the coupled product 27 was obtained at 140°C (Scheme 25.5A)P These conditions appear to be general and enabled halogenated examples to be synthesized in 46 to 63% yields. 

Several different transition metal-catalyzed reactions with the 2(li-f)pyrazinone template have been evaluated. The Suzuki-Miyaura coupling was efficient in introducing aryl groups to both the 3 and the 5-positions of the heterocycle. The 3-arylated product could be isolated in 75% yield by using 1.1 equivalents of boronic acid and sodium carbonate as base whereas use of 2.2 equivalents of boronic acid with cesium carbonate yielded the 3,5-disubstituted compound in 52% yield (Scheme 15.21) [56]. Efforts to widen the utility of this Suzuki-Miyaura reaction to include solid-phase reactions met with difficulties, because the reaction was problematic to drive to completion [57]. Other teams have also reported problems with Suzuki-Miyaura couplings on polymeric supports [44, 58]. 

It has been proven that the chiral Pd(II) complexes as transition metal catalysts vs Lewis acid catalysts bring a breakthrough in the frontier of catalytic asymmetric organic synthesis. Here we discussed the key issues based on asymmetric carbon-carbon bond formations anomalous six-membered ring formation, ene-type cyclization leading to five-membered rings, spiro cycliza-tion, alkaloid and quinoline synthesis, Suzuki-Miyaura coupling, and C-H bond activation/C-C bond formation by transition metallic Pd(II) catalysts. On the other hand, the carbonyl-ene reaction, hetero Diels-Alder reaction, and... 

Suzuki-Miyaura Coupling. The Suzuki-Miyaura coupling reaction is very useful for construction of carbon-carbon bonds under mild conditions. Because it is tolerant of many functional groups, it has been employed widely in the synthesis of many natural products and related compounds. The stereochemistry of such coupling reactions proceeds with retention of configuration at both the C-X and C-(9-BBN) centers, confirmed recently hy independent studies from the groups of Woerpel and Soderquist. ... 

In the field of catalysis, Au NPs appear to be particularly important as an efficient catalyst in organic reactions it can offer the most favourable combination of activity and selectivity in various catalytic reactions such as electrocatalysis, redox catalysis, carbon-carbon bond formation, and photocatalytic reactions. Moreover, recent literature reported that the Au NPs-graphene composites exhibit unprecedented catalytic activity for CO oxidation, reduction of nitro-aniline and Suzuki-Miyaura coupling reaction of chlorobenzene with arylboronic acid. 

The Suzuki-Miyaura coupling has traditionally been carried out using palladium as the metal catalyst however, there have been several reports that employ alternative metals as catalysts for the coupling reaction. In fact a rather controversial report even disclosed the use of no metal catalyst however, on careful examination of the reaction conditions it was found that palladium contaminants down to a level of 50 ppb found in commercially available sodium carbonate were responsible for the generation of the biaryl rather than an alternative non-palladium-mediated reaction. ... 

A dichromium derivative has been prepared from pinacol (dichloromethyl)-boronate (163), anhydrous chromous chloride, and lithium iodide in THF at 25 °C [90]. With various aldehydes, RCHO, this reagent adds to the carbonyl carbon to form trans-l-alkenylboronic esters, RCH=CH-B(02C2Me4). For most examples yields were 84-91%, E Z ratios >95 5. This reaction was used recently to convert aldehyde 162 into alkenylboronic ester 164, an intermediate used for a Suzuki-Miyaura coupling in the asymmetric total synthesis of quinine and quinidine (Scheme 8.39) [91]. In the modified procedure, the chromium reagent was generated from 163 in the presence of the aldehyde substrate. 

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