Synthesis of 5-arylhistidines via a Suzuki-Miyaura cross-coupling

Microwave irradiation efficiently promoted the Suzuki-Miyaura reaction of a 5-bromohistidine with various arylboronic acids in the presence of a palladium catalyst. This methodology allowed the synthesis of histidines substituted at position 5 of the imidazole ring with a phenyl, a substituted phenyl, a pyridyl or a thienyl ring. The corresponding 5-arylhistidines were obtained in moderate to good yields.     

Sonogashira反应研究的最新进展

对Sonogashira反应的最新研究进展作了综述. 详细地介绍了Sonogashira 反应的最新优化、联串化、绿色化以及非Pd催化的Sonogashira反应等, 同时还综述了Sonogashira反应的机理研究.     

Palladium-catalyzed cross-coupling reaction of alkynylzincs with benzylic electrophiles

The reaction of alkynylzinc bromides with benzyl bromides or chlorides in the presence of a catalytic amount of Pd(DPEphos)Cl₂ in THF at 23 °C cleanly produces the corresponding benzylated alkynes in 73-97% yields. With 10⁻³ mol % of Pd(DPEphos)Cl₂, the maximum turnover number of 7.1 × 10⁴ has been observed for the formation of PhCCCH₂Ph.     

Highly regio- and stereoselective hydrometallation reactions of fluorine-containing internal alkynes: Novel approaches to fluoroalkylated alkenes

Hydroalumination, hydrocupration, and hydroboration reactions of various fluorine-containing alkynes were investigated. The alkyne reacted smoothly with 2.0 equiv. of Red-Al at −78 °C to give the hydroaluminated adduct in a highly regio- and stereoselective manner, which was treated with iodine, the corresponding vinyliodide being produced in moderate yield. Hydrocupration of the alkynes also took place, but the resulting vinylmetal reacted with various electrophiles sluggishly. In sharp contrast, the reaction with dicyclohexylborane proceeded smoothly to afford the cis-addition products preferentially, which were subjected to Suzuki-Miyaura cross-coupling reaction, leading to trisubstituted alkenes in high yields.     

Synthesis, resolution and racemisation studies of new tridentate ligands for asymmetric catalysis

A method for the high-yielding preparation of two tridentate, isoquinoline-derived ligands, involving successive Suzuki cross-coupling reactions, is described. The first ligand could be resolved via molecular complexation with N-benzylcinchonidinium chloride, while the second was resolved by chromatographic separation of its epimeric camphorsulfonates. The barrier to rotation about the central biaryl axis was evaluated via racemisation studies, and the absolute configuration assigned by X-ray crystallography.     

Total synthesis of 1-(Z)-atractylodinol

The total synthesis of 1-(Z)-atractylodinol, a natural polyacetylenic alcohol with several biological activities, has been achieved using a newly developed telluride synthon and a novel use for the Negishi type coupling reaction employing vinyl tellurides.     

Polymer-supported DABCO–palladium complex as a stable and reusable catalyst for room temperature Suzuki–Miyaura cross-couplings of aryl bromides

Polymer-supported DABCO–palladium complex was observed as to be efficient and reusable catalytic system for the Suzuki–Miyaura cross-coupling reaction. In the presence of 0.25 mol % of the polymer-supported DABCO–palladium complex, a variety of aryl bromides were coupled with arylboronic acids efficiently in an aqueous ethanol at room temperature under air. Moreover, the reaction was very rapid, and the catalyst could be recovered readily from the reaction by simple filtration and could be reused at least five times.     

Cyclopalladated ferrocenylimine: a highly effective catalyst for the borylation/suzuki coupling reaction

The cyclopalladated ferrocenylimine was an efficient catalyst for the borylation/Suzuki coupling reaction. The catalytic loading for the reaction containing bromoarenes was 1 mol %. When iodobenzene was used, the catalytic loading was as low as 0.1 mol %. Furthermore, the cyclopalladated ferrocenylimine also exhibited excellent catalytic power in the case of substrates containing electron-donating substituents, with yields reaching 93% or higher.     

High yield thiolation of iodobenzene catalyzed by the phosphinite nickel PCP pincer complex: [NiCl{C6H3-2,6-(OPPh2)2}]

[NiCl{C₆H₃-2,6-(OPPh₂)₂}] efficiently catalyzes the thiolation of iodobenzene with a broad scope of disulfides in the presence of zinc, the coupled products are obtained in excellent and in many cases nearly quantitative yields.     

Palladium catalyzed ligand-free Suzuki cross-coupling reactions of benzylic halides with aryl boronic acids under mild conditions

A highly efficient Suzuki cross-coupling reaction between benzylic halides and aryl boronic acids using palladium chloride as catalyst in acetone:water (3:1) as the solvent system has been developed. High yields of products, mild reaction conditions and short reaction times in the absence of ligand are important features of this method.