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Suzuki-Miyaura conditions

Trapping the palladium species by transmetalation in a Suzuki-Miyaura coupling shows a very similar trend (Table 2) [38], By modifying the original Suzuki-Miyaura conditions [54] by the addition of water and pivalic acid [37], the palladium can migrate between the two o-positions before being trapped by... [Pg.129]

The Suzuki-Miyaura reaction suffers from a few key drawbacks, the first of which is the requirement for basic conditions. A number of monomers may be unstable in basic conditions, thus rendering this methodology impractical for these applications, or require more complex protection-deprotection strategies. Also, the Suzuki-Miyaura reaction requires a two-phase system thus, polymers that rapidly decrease in solubility as molecular weight increases may form precipitate in poor yields or display very low molecular weights and high polydispersities under Suzuki-Miyaura conditions, which is disadvantageous for photovoltaic application. [Pg.29]

The reaction of fluorinated nitro(orthonitrophenyl)imidazole with aryl boronic acids under Suzuki-Miyaura conditions is unusual in that it leads to displacement of fluoride and formation of O-arylated products, such as (106). It is possible that the pathway involves initial reaction of substrate with base to give a nitrophenyl derivative, which reacts by an Ar mechanism with more substrate to give a diphenyl ether before... [Pg.236]

The Suzuki-Miyaura and Heck reactions were recently also reported under conventional heating conditions [39,40]. A variety of 3-chloro pyrazinones were reacted with commercially available (hetero)aryl boronic acids or the alkyl-9-BBN derivatives under either classical or slightly modified Suzuki conditions to generate the 3-substituted analogues, however having the drawback of longer reaction times of up to 12 h of reflux. [Pg.278]

Scheme 16 Suzuki-Miyaura and Heck reactions at the C-5 position under conventional heating conditions... Scheme 16 Suzuki-Miyaura and Heck reactions at the C-5 position under conventional heating conditions...
Organoboron compounds cannot react without proper activation. The use of oxygen bases is inherent in the standard Suzuki-Miyaura cross-coupling method. Fluorides (usually CsF) can be used as alternative activating agents, which is particularly useful in cases when the reagents are incompatible with oxygen bases for the reactions run under anhydrous conditions,24 (66) 241 Fluoride activation can be effective, however, even under aqueous phase-transfer conditions (67) 242... [Pg.328]

Another way to produce biphenyl derivates using flow was described by Leeke et al. [34] where they performed a Pd catalyzed Suzuki-Miyaura synthesis in the presence of a base. First experiments were carried out in toluene/methanol solvent. A reaction mixture was passed through the encapsulated Pd filled column bed length 14.5 cm (some cases 10 cm) x 25.4 mm id. 45 g of PdEnCat. Base concentration, temperature and flow rate were optimized and at optimum parameters (0.05 M base concentration, 100°C and 9.9 mL/min) the conversion was 74%. Then the reaction was performed under supercritical conditions using supercritical CO2 at high pressure and temperature. After optimizing the concentration of base, flow rate, pressure and temperature, the highest conversion rate (81%) was observed at 166 bar and 100°C where the reactant mixture was monophasic in the supercritical state. This system is able to produce 0.06 g/min of the desired product. [Pg.409]

Heterogeneous Pd catalysts can activate the C-Cl bond in aryl chlorides for the Suzuki-Miyaura reaction, presumably due to a synergistic anchimeric and electronic effect that occurs between the Pd surface and the aryl chlorides. Pd on carbon has been found to be a very effective pre-catalyst for a variety of substrates even under very mild reaction conditions and aqueous solvent mixtures.In 2001, Kabalka and co-workers described that Pd powder and KF as base were useful to couple aryl iodides with arylboronic acids in methanol." At the conclusion of the reaction, Pd metal could be recovered by simple decantation. The use of microwave irradiation accelerates the reaction by... [Pg.10]

Vinylsilanes react with boron trichloride to give the corresponding borodesilylation products in good yield which, in turn, can be transformed into boronic esters 124 by alcoholysis (equation 102). The initial dichloroorganoborane products can be used directly in the Suzuki-Miyaura cross-coupling reaction192. Replacement of a carbon-silicon bond by a carbon-tin bond in fluorinated alkenes (e.g. 125) can be achieved by the reaction of silanes with Bu3SnCl and KF in DMF under mild conditions (equation 103)193. It is... [Pg.1828]

An interesting polymer-assisted variant of the Suzuki-reaction was recently disclosed by Vaultier and coworkers (Scheme 17) [43]. Aryl boronic acids can be immobilized on an ion exchange resin. Under Suzuki-Miyaura coupling conditions bisaryl species are released into solution and isolated with minimum purification. The authors also demonstrated that this strategy can be employed for the synthesis of macroheterocycles. [Pg.275]


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