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Showing 1 to 17 of 17 for “"biaryls"”.
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Studies on extensions of tert-amino effect: Ring-fusion to bridged biaryls and steroids
… of tert-amino effect: Ring-fusion to bridged biaryls and steroids The term t (later tert)-amino effect was introduced by Meth-Cohn and Suschitzky to generalize the thermal isomerization of ortho-substituted tertiary anilines to benzo-fused heterocyclic systems. In type 2 reactions, an …
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i) Design and Synthesis of Butadiene Substrates for Organocatalytic Transformations ii) Synthesis of Functionalized Biaryls and Pyran Derivatives
… then turned to the directed synthesis of these biaryls. This was accomplished through the use of stoichiometric quantities of piperidine in order to reduce the potential for polymerization or side-reactions which would consume the starting material. A study into the aromatization of the cyclic …
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Ketone -Catalyzed Epoxidation of Alkenes With Oxone and Palladium -Catalyzed Biaryl Synthesis via Silacyclobutanes
… different and structurally diverse unsymmetrical biaryls have been prepared in good to excellent yields.
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Development of transitional metal-catalyzed reactions for organic synthesis
… for the synthesis of tetra-ortho-substituted biaryls via the Suzuki-Miyaura cross-coupling reaction is described. It was found that the most efficient catalyst system is based on a phenanthrene-substituted biaryl phosphine ligand. Utilizing this ligand, a number of tetra-ortho-substituted …
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The synthesis and applications of a biaryl-based asymmetric phosphine ligand
… 1-bromo-2- methoxynaphthalene, to synthesize biaryls in modest enantioselectivity.
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Developing and Understanding Iridium-Catalysed Arene Borylation
… This procedure allows efficient synthesis of biaryls by initial C-H borylation of aromatic substrates followed by addition of water, subsequent reagents and aryl halide to complete the Suzuki-Miyaura cross-coupling without the need for change in reaction solvent. Another issue associated with …
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Manganese-catalyzed carbonylation of alkyl iodides
… at the synthesis of tri- and tetra substituted biaryls, since they are important precursors to biaryl phosphine ligands. The project did not succeed due to stability problems of the formed substituted zirconium biaryl. A general method for the manganese-catalyzed carbonylation of alkyl iodides …
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Recent advances in palladium-catalyzed carbon-carbon and carbon-boron bond forming processes
… for the preparation of a wide variety of heterobiaryls in good to excellent yields and displays a high level of activity for the coupling of heteroaryl chlorides as well as hindered aryl and heteroaryl halides. Specific factors that govern the efficacy of the transformation for certain …
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Bipyridine Ligands for use in Polymer-Supported Iridium Catalyzed C-H Borylation
… excellent yields of pyridine containing biaryls through the direct addition of aryl lithiation to pyridines have been reported. This aroused interests for generating bipyridine ligands in an analogous fashion. Although this new route to synthesis bipyridine ligands was not completed, this …
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Investigation of aryldimethylsilanolates in palladium-catalyzed cross-coupling reactions and development of chiral bis-hydrazone ligands for asymmetric aryl-aryl couplings
The preparation of biaryls by palladium-catalyzed cross-coupling of aromatic bromides and chlorides with alkali-metal salts (potassium and sodium) of aryl- and heteroarylsilanols has been developed. The critical feature for the success of this method is the use of …
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Control of selectivity in palladium-catalysed cross-coupling reactions using a sulfonated phosphine ligand
… being observed. The formation of atropisomeric biaryls was investigated with a wide range of coupling partners, with moderate to good enantioselectivity observed for coupling partners containing polar functionality. Excellent enantioselectivity was observed for the synthesis of 2,2’-biphenols: a …
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Preparative and mechanistic aspects of palladium-catalyzed cross-coupling reactions of alkali-metal arylsilanolates
… organometallic reagents for the preparation of biaryls has been realized through in depth mechanistic and preparative studies. The alkali-metal salts (potassium and sodium) of a large number of arylsilanols undergo smooth cross-coupling with a wide range of aromatic bromides and chlorides. The …
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The Development of Asymmetric Palladium-Catalysed Transformations Using Chiral Sulfonated Phosphine Ligands
… cross-couplings to form atropisomeric biaryls with a range of coupling partners. Generally excellent levels of enantioselectivity were observed when both coupling partners contained hydroxy groups ortho to the newly formed biaryl bond, to form 2,2’-biphenols. This was later applied to …
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Synthesis, Activation and Catalytic Activity of N-Heterocyclic Carbene Bearing Palladium Catalysts
… to the synthesis of poly-ortho-substituted biaryls in excellent yields. This catalyst loading is the lowest ever used for this purpose. The system also allows for the first examples of coupling between aryl chlorides and alkenyl boronic acids at room temperature. When the temperature is …
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Studies on organic electron donors and their applications in chemistry
… presence of potassium tert-butoxide 17 to form biaryls 18-24 via electron transfer [graphic of electron transfer process].;It also investigates the different outcomes of the reaction when a diketopiperazine is used or not, providing evidence for formation of a benzyne intermediate which can lead …
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Synthetic Studies Towards the Crisamicins
… acetyl group at C-7 and C-7’ onto the initial biaryls 2.8b and 2.8d. Attention then turned to the synthesis of the bis-7-acetylnaphthalene 1,268 that was required for the ensuing furofuran annulation reaction starting from triflate 2.7 that already contained an acetyl group at C-7, then …
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New methodologies and approaches to reaction discovery in transition metal catalysis
… unstable organoboronates was developed. Biaryls in which one or more of the aryl rings are heteroarenes or fluorinated arenes are found widely in medicinal chemistry and materials science, but are challenging to prepare by Suzuki-Miyaura coupling because of the instability of the …