885273-16-5Relevant articles and documents
N, C-Disubstituted Biarylpalladacycles as Precatalysts for ppm Pd-Catalyzed Cross Couplings in Water under Mild Conditions
Thakore, Ruchita R.,Takale, Balaram S.,Gallou, Fabrice,Reilly, John,Lipshutz, Bruce H.
, p. 11647 - 11657 (2019/11/29)
Various monosubstitution and disubstitution patterns on the parent biarylamine skeleton characteristic of palladacycles, as well as the counterion effect, have been studied while looking for ways to increase the effectiveness of the catalyst formed under micellar catalysis conditions in water, with the goal of reducing the amount of Pd needed for coupling reactions. Several substituted palladacycles containing readily accessible ligands were chosen for evaluation. The results indicate that (1) preactivation of Pd(II) salts as precursors for Suzuki-Miyaura (SM) couplings via treatment with a reducing agent is not required; (2) reactions could be performed with approximately half the loading of Pd, relative to that previously required based on a combination of a Pd(II) salt and ligand; and (3) the most effective palladacycle precatalyst has been identified as that containing an isopropyl group on both an aryl ring and on nitrogen, together with the ligand EvanPhos and triflate as the counterion (P13). This precatalyst is also effective in other C-C bond-forming reactions, such as Heck and Sonogashira couplings. No organic solvents were needed for these processes, while the aqueous reaction medium could be recycled several times. A one-pot, four-step sequence involving Suzuki-Miyaura, reduction, alkylation, and acylation reactions highlights the potential for this precatalyst to maximize synthetic gain while minimizing costs and waste generation.
Design of a versatile and improved precatalyst scaffold for palladium-catalyzed cross-coupling: (η3-1-tBu-indenyl)2(μ-Cl)2Pd2
Melvin, Patrick R.,Nova, Ainara,Balcells, David,Dai, Wei,Hazari, Nilay,Hruszkewycz, Damian P.,Shah, Hemali P.,Tudge, Matthew T.
, p. 3680 - 3688 (2015/06/16)
We describe the development of (η3-1-tBu-indenyl)2(μ-Cl)2Pd2, a versatile precatalyst scaffold for Pd-catalyzed cross-coupling. Our new system is more active than commercially available (η3-cinnamyl)2(μ-Cl)2Pd2 and is compatible with a range of NHC and phosphine ligands. Precatalysts of the type (η3-1-tBu-indenyl)Pd(Cl)(L) can either be isolated through the reaction of (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 with the appropriate ligand or generated in situ, which offers advantages for ligand screening. We show that the (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 scaffold generates highly active systems for a number of challenging cross-coupling reactions. The reason for the improved catalytic activity of systems generated from the (η3-1-tBu-indenyl)2(μ-Cl)2Pd2 scaffold compared to (η3-cinnamyl)2(μ-Cl)2Pd2 is that inactive PdI dimers are not formed during catalysis.
SLOW RELEASE OF ORGANOBORONIC ACIDS IN CROSS-COUPLING REACTIONS
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Page/Page column 53, 55-56, (2010/04/27)
A method of performing a chemical reaction includes reacting a compound selected from the group consisting of an organohalide and an organo-pseudohalide, and a protected organoboronic acid represented by formula (I) in a reaction mixture: R1-B-T; where R1 represents an organic group, T represents a conformationalIy rigid protecting group, and B represents boron having sp3 hybridization. When unprotected, the corresponding organoboronic acid is unstable by the boronic acid neat stability test. The reaction mixture further includes a base having a pKB of at least 1 and a pal ladium catalyst. The method further includes forming a cross-coupled product in the reaction mixture.