The direct Michael addition of enolizable aldehydes to dimethyl(phenyl)silylmethylene malonate was catalysed by an (S)-diphenylprolinol trimethylsilyl ether/acetic acid combination. The adducts were formed in good yield, high diastereoselectivity and excellent enantioselectivity. Chiral valerola...
Carbonyl cobalt complexes serve as catalysts or catalyst precursors for the facile and selective transformation of primary diazoalkanes into the corresponding ketene. The mechanism of this carbonylation reaction has been elucidated in the case of ethyl diazoacetate as model diazoalkane using oct...
The conjugate addition of O-benzylhydroxylamine and N,O-bis(trimethylsilyl)hydroxylamine to alkylidene and arylidene malonates in the presence of Lewis acids affords the corresponding β-hydroxylamino derivatives in good yields. The use of Cu(OTf)2 in the presence of chiral bisoxazoline ligands ...
Alkylation of racemic 1-(6-methoxynaphth-2-yl)ethyl acetate by potassium dimethyl malonate catalyzed by a chiral palladium-DUPHOS complex afforded the substitution product with 87% ee, along with 6-methoxy-2-vinylnaphthalene that arose from an elimination process, in a 43/57 substitution/elimina...
Reaction of dimethylsulfoxonium methylide with a β-silylmethylene malonate gives diversified products, cyclopropane, cyclobutane or allyl and homoallyl silanes depending upon the stoichiometry of the reactants and reaction conditions. Contrary to this, reaction of a β-arylmethylene malonate gi...
An efficient, convenient, and reliable multi-step synthesis of rac-2′-(trimethylsilyl)isovaline (rac-3) that uses inexpensive reagents in all steps has been developed, starting from diethyl malonate (overall yield 28%). Compound rac-3 is the first α-ethylated α,α-dialkylated silicon-containi...
(TMS)ethyl malonate can be generated in-situ by treating potassium ethyl malonate with trimethylsilyl chloride and acylated with aliphatic or aromatic acyl imidazoles or chlorides in the presence of DBU to prepare a variety of β-ketoesters. This constitutes a high yield method for preparing β-...
A direct route to acyl furans was developed using dithiane anion addition followed by deprotection/aromatization. This led to an efficient synthesis of hibiscone C.
A facile and highly efficient approach for selective O-difluoromethylation of 1,3-diones by recently developed bench-stable S-(difluoromethyl)sulfonium salt was described. And a broad range of difluoromthyl enol ethers were readily accessed in good to excellent yields under mild reaction conditi...
In this work, boron carbide (B4C) was selected as additive to improve the tribological performance of C/C-SiC brake materials. It contained four phases (C, B4C, Si and SiC) in B4C modified C/C-SiC (C/C-B4C-SiC) brake materials. Its wear rates were much less than that of C/C-SiC, especially at hi...
Chronic hepatitis C is the most common blood-borne pathogen worldwide. Upwards of half of the individuals infected with hepatitis C have not been diagnosed, and rates of screening remain low. Incidence, which had been declining, began increasing in 2011, mirroring the current opioid epidemic. On...
To widen the applications of conventional reactive melt infiltration (RMI) in large-sized complex-shaped C/C components, an ingenious process of gel-RMI (GRMI) was proposed in this study. The arching C/CSiC composite was prepared successfully using GRMI method with polycarbosilane (PCS)Si90Zr10 ...
Background and aimsThe SPINK1 c.194 + 2T > C variant has been increasingly recognized as an important risk factor for chronic pancreatitis (CP). However, there is no clear agreement on its contribution to different ethnicities and CP etiologies. To address this issue, a meta-analysis of literatu...
Mosaic structure ZrC-SiC coatings were fabricated on low-density, porous C/C composites via thermal evaporation and an in-situ method. ZrC was packed in a typical lamellar mode, and the mosaic structure was formed by the deposition of Zr and Si atoms on the shallow surface of the porous C/C comp...
The new C-scorpionate Ni(II) complex [NiCl{κ3-HC(pz)3}]Cl (pz = pyrazol-1-yl) is the first nickel homoscorpionate tris(pyrazol-1-yl)methane type complex to be applied as catalyst for the Heck–Mizoroki C–C cross coupling. The microwave-assisted reaction of butyl acrylate and 4-halogeno-anisole...
In this work, tribological properties of different FeSi2-modified C/C–SiC composites have been studied using disk-on-disk type laboratory scale dynamometer. Results indicated that line wear rate decreased significantly with the introduction of FeSi2 in C/C–SiC. In addition, when C/C–SiC is mo...
Silicon-containing molecules are of great academic and industrial interest with widespread applications in several research areas such as materials science, medicinal chemistry, and complex-molecule synthesis. C–Si bond formation by direct C–H functionalization is a modern synthetic approach t...
How long a CC bond can be? A question has long fascinated chemists. This work reports an example of extraordinary long CC bond distance of 1.990(4) Å observed in single-crystal X-ray structure of 1,2-(NHMes)2-o-carborane (2; Mes = 2,4,6-trimethylphenyl). DFT calculations show that hyperconjugati...
A practical synthetic route to 2-substituted aminophenyl and hydroxyphenyl pyridines has been developed. It has been accomplished by the cross-coupling reactions of readily available 2-pyridylzinc bromides with haloaromatic amines and alcohols under mild conditions.
Ruthenium complexes containing terpyridine or the 4′-substituted terpyridines and 2-(hydroxyphenyl)-benzoxazole (HPB) have been synthesized and characterized. The crystal structures of three of the complexes have been determined. All three complexes, trans-[Ru(tolylterpy)(HPB)(Cl)](PF6), cis-[R...
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