The Experts below are selected from a list of 14364 Experts worldwide ranked by ideXlab platform
Di Shen - One of the best experts on this subject based on the ideXlab platform.
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a bulky chiral n heterocyclic carbene palladium catalyst enables highly enantioselective suzuki miyaura cross coupling reactions for the synthesis of Biaryl atropisomers
Journal of the American Chemical Society, 2019Co-Authors: Di Shen, Youjun XuAbstract:Axially chiral Biaryl scaffolds are essential structural units in chemistry. The asymmetric Pd-catalyzed Suzuki–Miyaura cross-coupling reaction has been widely recognized as one of the most practical methods for constructing atropisomers of Biaryls. However, longstanding challenges remain in this field. For example, substrate scope is often narrow and specialized, functional groups and heterocycles can lead to reduced reactivity and selectivity, bulky ortho-substituents are usually needed, and reported methods are generally inapplicable to tetra-ortho-substituted Biaryls. We have developed an unprecedented highly enantioselective N-heterocyclic carbene (NHC)-Pd catalyzed Suzuki–Miyaura cross-coupling reaction for the synthesis of atropisomeric Biaryls. These reactions enable efficient coupling of aryl halides (Br, Cl) or aryl triflates with various types of aryl boron compounds (B(OH)2, Bpin, Bneo, BF3K), tolerate a remarkably broad scope of functional groups and heterocycles (>41 examples), employ low lo...
Youjun Xu - One of the best experts on this subject based on the ideXlab platform.
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a bulky chiral n heterocyclic carbene palladium catalyst enables highly enantioselective suzuki miyaura cross coupling reactions for the synthesis of Biaryl atropisomers
Journal of the American Chemical Society, 2019Co-Authors: Di Shen, Youjun XuAbstract:Axially chiral Biaryl scaffolds are essential structural units in chemistry. The asymmetric Pd-catalyzed Suzuki–Miyaura cross-coupling reaction has been widely recognized as one of the most practical methods for constructing atropisomers of Biaryls. However, longstanding challenges remain in this field. For example, substrate scope is often narrow and specialized, functional groups and heterocycles can lead to reduced reactivity and selectivity, bulky ortho-substituents are usually needed, and reported methods are generally inapplicable to tetra-ortho-substituted Biaryls. We have developed an unprecedented highly enantioselective N-heterocyclic carbene (NHC)-Pd catalyzed Suzuki–Miyaura cross-coupling reaction for the synthesis of atropisomeric Biaryls. These reactions enable efficient coupling of aryl halides (Br, Cl) or aryl triflates with various types of aryl boron compounds (B(OH)2, Bpin, Bneo, BF3K), tolerate a remarkably broad scope of functional groups and heterocycles (>41 examples), employ low lo...
Anna Iuliano - One of the best experts on this subject based on the ideXlab platform.
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deoxycholic acid derived monophosphites as chiral ligands in the asymmetric suzuki miyaura cross coupling
Tetrahedron-asymmetry, 2011Co-Authors: Varsha R Jumde, Anna IulianoAbstract:Abstract Biaryl phosphites derived from deoxycholic acid were used as chiral ligands in the asymmetric Suzuki–Miyaura cross-coupling of arylboronic acids with aryl bromides. Amongst the different reaction parameters, the role of the base emerged as being crucial for the outcome of the reaction: the choice of base, and its amount, allowed enantiomerically enriched Biaryl derivatives to be obtained at 1% catalyst loading and with an L:Pd ratio of 1:1.
Mark Lautens - One of the best experts on this subject based on the ideXlab platform.
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palladium catalyzed reductive ortho arylation evidence for the decomposition of 1 2 dimethoxyethane and subsequent arylpalladium ii reduction
Organic Letters, 2010Co-Authors: Andrew Martins, David A Candito, Mark LautensAbstract:A palladium-catalyzed crossed Biaryl coupling/reduction sequence enables the formation of meta-substituted Biaryls via solvent-mediated arylpalladium(II) reduction. Isotope labeling studies determined that the decomposition of 1,2-dimethoxyethane (DME) is indeed involved in the reductive process.
Bruce H. Lipshutz - One of the best experts on this subject based on the ideXlab platform.
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Kumada–Grignard-type Biaryl couplings on water
Nature Communications, 2015Co-Authors: Anish Bhattacharjya, Piyatida Klumphu, Bruce H. LipshutzAbstract:Well-established, traditional Kumada cross-couplings involve preformed Grignard reagents in dry ethereal solvent that typically react, e.g., with aryl halides via Pd catalysis to afford products of net substitution. Therefore, in the work described, which appears to be counterintuitive, exposure of these same aromatic halides to catalytic amounts of Pd(II) and excess magnesium metal in pure water leads to symmetrical/unsymmetrical Biaryls, indicative of a net Kumada-like Biaryl coupling. Evidence is presented suggesting that Grignard reagents, formed in situ in water, may be involved.
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Kumada–Grignard-type Biaryl couplings on water
Nature Communications, 2015Co-Authors: Anish Bhattacharjya, Piyatida Klumphu, Bruce H. LipshutzAbstract:Organomagnesium reagents have been a staple for carbon–carbon bond formations for over a century, but are notoriously sensitive to water. Here, the authors show a Kumada-type coupling of aryl halides on water, with a potential intermediary of an in situ formed Grignard reagent. Well-established, traditional Kumada cross-couplings involve preformed Grignard reagents in dry ethereal solvent that typically react, e.g., with aryl halides via Pd catalysis to afford products of net substitution. Therefore, in the work described, which appears to be counterintuitive, exposure of these same aromatic halides to catalytic amounts of Pd(II) and excess magnesium metal in pure water leads to symmetrical/unsymmetrical Biaryls, indicative of a net Kumada-like Biaryl coupling. Evidence is presented suggesting that Grignard reagents, formed in situ in water, may be involved.
