Ruthenium-catalyzed synthesis of allylic alcohols: boronic acid as a hydroxide source

Secondary allylic alcohols were synthesized from linear allylic halides or carbonates using a catalytic amount of a ruthenium complex in the presence of boronic acid. The effects of solvent, base, ruthenium precursor, and boronic acid were fully explored, and the scope of the reaction was extended to various substrates. We also describe a preliminary investigation towards an enantioselective process.     

Application of the intramolecular isomerisation-aldolisation from allylic alcohols and allylic silyl ethers to the synthesis of indanones and indenones

A new access to indanones was discovered through a one-step nickel or iron-mediated transposition of 2-hydroxyisobenzofurans. Starting from the corresponding silylenol ethers, a new one-pot tandem isomerisation-Mukaiyama aldol process was also developed. These versatile strategies will be useful for the preparation of various types of indanones and indenones.     

Highly enantioselective allylic alkylation catalyzed by new P,N -chelate ligands from L-valinol

Newly synthesized chiral P,N-chelate ligands gave high enantioselectivities in the alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate system. High enantiomeric excess up to 98% could be obtained in a good yield.     

烯丙基转移反应合成直链高烯丙基醇

研究了不同脂肪族和芳香族醛与6-甲基-6-苯基-7-烯-1,5-辛二醇的烯丙基转移反应, 同时考察了溶剂对反应的影响. 结果发现, 在In(OTf)3催化下, 以甲苯为溶剂, 由脂肪族醛合成的直链高烯丙基醇较芳香族醛具有较高的产率和较好的选择性, 所得产物结构经1H NMR, 13C NMR, IR, HRMS表征.     

(N,N) vs. (N,S) chelation of palladium in asymmetric allylic substitution using bis(thiazoline) ligands: A theoretical and experimental study

New thiazoline-containing ligands including non-symmetric bis(thiazolines) and oxazoline-thiazolines were synthesized and then compared to C₂-symmetric bis(thiazolines) in the palladium-catalyzed allylic substitution. The experimental results obtained in this study support the hypothesis of a competition between the (N,N) and the (N,S) palladium chelation, when sterically hindered bis(thiazolines) are used as ligands. A quantum chemical study performed on the Pd-complexes derived from three selected ligands, two C₂-symmetric bis(thiazolines) and one oxazoline-thiazoline, also supports this hypothesis.     

Modular chiral β-selenium-, sulfur-, and tellurium amides: synthesis and application in the palladium-catalyzed asymmetric allylic alkylation

A series of modular chiral β-chalcogen amides have been efficiently synthesized from inexpensive and easily available 2-oxazolines. All the selenium, sulfur, and tellurium compounds were evaluated as chiral ligands in the palladium-catalyzed asymmetric allylic alkylation. The corresponding alkylated products were obtained in excellent enantiomeric excess, using BSA/CH₂Cl₂ as the base/solvent system.     

Tethering hydrophilic polymer brushes onto PPESK membranes via surface-initiated atom transfer radical polymerization

Surface-initiated atom transfer radical polymerization (ATRP) was used to graft hydrophilic comb-like poly((poly(ethylene glycol) methyl ether methacrylate), or P(PEGMA), brushes from chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) membrane surfaces. Prior to ATRP, chloromethylation of PPESK was beforehand performed and the obtained CMPPESK was prepared into porous membranes by phase inversion process. It was demonstrated that the benzyl chloride groups on the CMPPESK membrane surface afforded effective macroinitiators to graft the well-defined polymer brushes. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the grafting of P(PEGMA) chains. Water contact angle measurements indicated that the introduction of P(PEGMA) graft chains promoted remarkably the surface hydrophilicity of PPESK membranes. The effects of P(PEGMA) immobilization on membrane morphology, permeability and fouling resistance were investigated. It was found that the comb-like P(PEGMA) grafts brought smaller pore diameters and higher solute rejections to PPESK membranes. The results of dynamic anti-fouling experiments showed the anti-fouling ability of the membranes was significantly improved after the grafting of P(PEGMA) brushes.     

Sulfonated poly(arylene ether sulfone) ionomers containing fluorenyl groups for fuel cell applications

A series of sulfonated poly(arylene ether sulfone)s (SPEs) containing fluorenyl groups as bulky components were synthesized and characterized for fuel cell applications. Introduction of disodium 3,3′-disulfo-4,4′-difluorophenyl sulfone (SFPS) monomer gave ionomers with high acidity and accordingly high proton conductivity as well as high proton diffusion coefficient (D_σ) at low humidity. The membrane of SPE60 (where the number denotes mole percentage of the component containing sulfonic acid groups; IEC (ion exchange capacity) = 1.68 mequiv./g) exhibited high proton conductivity of 4.6 × 10⁻³ S/cm at 40% RH and 80 °C, which is one order of magnitude higher than that (6 × 10⁻⁴ S/cm) of our previous SPE (SPE-1, IEC = 1.58 mequiv./g). D_σ of SPE60 membrane was ca. 4 times higher than that of the SPE-1 membrane at low water volume fraction. SPE membranes showed good oxidative and hydrolytic stability as well as favorable thermal and mechanical properties. Small-angle X-ray scattering analyses showed that the phase separation of SPE membranes was much less developed than that of the perfluorinated Nafion membrane which accounts for lower hydrogen and oxygen permeability of the former membranes.     

Synthesis of novel chiral phosphine-triazine ligand derived from α-phenylethylamine for Pd-catalyzed asymmetric

A novel chiral phosphine-triazine ligand was synthesized from chiral α-phenylethylamine through a three-step procedure. In a model reaction of Pd-catalyzed allylic alkylation of rac-1,3-diphenylprop-2-en-1-y1 pivalate with dimethyl malonate, good enantioselectivity （90% e.e.） was obtained by using this ligand.