Palladium-catalyzed coupling of vinyl tosylates with arylsulfinate salts

The first palladium-catalyzed coupling of vinyl tosylates with arylsulfinate salts is described. A variety of cyclic and acyclic vinyl tosylates were coupled with aryl sulfinate salts using 2.5 mol % Pd₂(dba)₃/5.0 mol % XantPhos to give vinyl aryl sulfone products in good yields. The coupling was extended to the preparation of a cyclopropyl vinyl sulfone.     

Palladium-catalyzed cyclization of vinyl iodide-tethered allensulfonamide

This Letter describes a palladium-catalyzed cyclization of vinyl iodide-tethered allensulfonamide in the presence of alkylol, which provides a facile access to 2-alkoxy-3-methylene-tetrahydropyridine. The asymmetric version of this reaction has also been preliminarily realized with up to 81% enantioselectivity when chiral bisphosphine ligands were used.     

Palladium-catalyzed synthesis of quinoxaline derivatives

A palladium-catalyzed reductive N-heteroannulation of enamines derived from 2-nitrobenzenamines forming mixtures of 1,2-dihydroquinoxalines and 3,4-dihydroquinoxalin-2-ones is described. The reactions are performed using bis(dibenzylideneacetone)palladium(0), 1,3-bis(diphenylphosphino)propane, and 1,10-phenanthroline in DMF under 6 atm of carbon monoxide at 70 °C.     

Palladium-catalyzed oxidation of vinyl ether to acetate with hydrogen peroxide

The selective hydrogen peroxide oxidation of vinyl ethers to give acetates was developed using triphenylphosphine palladium and triethyl amine catalysts under mild reaction conditions.     

Palladium-catalyzed carbene insertion into vinyl halides and trapping with amines

Palladium is shown to catalyze the three-component coupling of vinyl halides, trimethylsilyldiazomethane, and amines to generate allylamines. The mechanism is believed to involve formation of an R-Pd=CHSiMe3 intermediate that undergoes migration of the vinyl ligand to the empty p-orbital of the carbene ligand. The resulting eta1-allylpalladium species forms an eta3-allylpalladium intermediate that is trapped by the amine nucleophile. Under the conditions tested, cyclic secondary amines and terminal vinyl iodides give the best results.     

Catalytic ethoxylation of phenol and phenol derivatives

The kinetics of catalytic mono- and polyethoxylation of phenol, p-cumyl-phenol and p-isooctylphenol have been studied in the presence of strongly basic anion exchanger Wofatit SBW in hydroxy form. The influence of substituents on the rate has been investigated and the mechanism of the reaction is discussed.

---

- , - Wofqtit SBW . .

     

Palladium-catalyzed amination of chloromethylnaphthalene and chloromethylanthracene derivatives with various amines

Palladium-catalyzed amination of chloromethylnaphthalene and chloromethylanthracene derivatives to produce naphthylamines and anthrylamines in satisfactory to good yields has been developed. The unprecedented amination reactions proceeded smoothly under mild conditions in the presence of Pd(PPh(3))(4) as a catalyst.     

吡咯和咪唑衍生物的钯催化环化反应

本文研究了吡咯和咪唑衍生物的钯催化反应。采用Pd(OAc)~2-2PPh~3为催化剂合成了一些骈环异吲哚类化合物。探讨了不同的钯化合物的区域选择性和催化作用。     

Palladium-catalyzed substitution reactions of 4-allylimidazole derivatives

In the context of synthetic studies toward the oroidin family of pyrrole-imidazole alkaloids, we required an efficient method for conducting substitution reactions of allylic alcohols derived from urocanic acid. While in some cases this could be accomplished quite readily by classical nucleophilic substitution, it was complicated by allylic transposition in others. Application of Pd-catalyzed π-allyl chemistry provided a convenient solution, giving substitution without allylic transposition. Herein we describe the scope of this reaction in imidazole-containing substrates, and the elaboration of one adduct into a homologated histidine derivative, and into a cyclic homohistidine derivative.     

Cross-coupling of mesylated phenol derivatives with potassium cyclopropyltrifluoroborate

C-O activation of mesylates by a palladium catalyst and subsequent cross-coupling with potassium cyclopropyltrifluoroborate have been achieved with high yield. Both electron-enriched and electron-deficient aryl mesylates are suitable electrophilic partners for the Suzuki-Miyaura reaction. The scope was successfully extended to heteroaryl mesylates with yields up to 94%.     

Cross-coupling of mesylated phenol derivatives with potassium alkoxymethyltrifluoroborates

Cross-coupling of mesylated phenol derivatives with various potassium alkoxymethyltrifluoroborates has been achieved. The corresponding aryl and heteroaryl alkoxymethyl compounds have been obtained with equal facility with both electron-rich and electron-poor substituents on the activated alcohol.     

Palladium-catalyzed coupling of tetraphenylbismuth(V) derivatives with methyl acrylate

Tetraphenylbismuth(V) derivatives of the general formula Ph₄BiX [X = OSO₂C₆H₄Me-4, OC₆H₂(NO₂)₃-2,4,6, OC₆H₂(NO₂-4)(Br₂-2,6), OSO₂C₆H₃(OH)(COOH)] react with methyl acrylate in the presence of palladium dichloride (1:3:0.04 molar ratio) in acetonitrile at 20°C to form the cross-coupling products, methyl cinnamate (0.17–0.54 mol mol^?1 starting bismuth compound) and methylhydrocinnamate (0.10–0.73 mol mol^?1), diphenyl (0.06–0.80 mol mol^?1), and benzene (0.02–0.36 mol mol^?1). The highest C-phenylating activity is shown by Ph₄BiOSO₂C₆H₄Me-4. The mechanisms with the palladium-catalyzed cross-coupling reactions are suggested.     

Palladium-catalyzed regioselective reactions of silyl-substituted allylic carbonates and vinyl epoxide

Palladium-catalyzed reaction of α-substituted γ-trimethylsilylated allylic carbonates with carbonucleophiles took place regioselectively at the α-carbon. Reaction of formic acid took place at γ-carbon to afford allylic silanes. Methyl acetoacetate attacked regioselectively at 2-carbon of 1,2-epoxy-4-trimethylsilyl-3-butene.     

Routes to fluorinated organic derivatives by nickel mediated C-F activation of heteroaromatics

New fluorinated azaheterocycles can be synthesised regio- and chemo-selectively via C-F activation of fluorinated precursors at nickel, with subsequent functionalisation and release from the coordination sphere of the metal; the requirements for productive C-F activation are significantly different from those for C-H bond activation.     

Palladium-catalyzed P-arylation of hydrophosphoryl derivatives of protected monosaccharides

Palladium-catalyzed arylation of hydrophosphorylated protected monosaccharides of the pyranose and furanose series gave the corresponding P-aryl derivatives.     

Transition-metal catalyzed enantioselective hydrofunctionalization of alkynes

A significant number of reactions regarding hydrofunctionalization of alkynes have appeared in the literature over the years. This digest focus on the transition-metal catalyzed enantioselective alkyne hydrofunctionalization reactions. Based on the reaction mechanism, these reactions described herein are classified into three types. Strategies, substrate scope, along with mechanisms are highlighting.     

Palladium-catalyzed direct ortho C-H arylation of 2-arylpyridine derivatives with aryltrimethoxysilane

A Pd(OAc)(2)-catalyzed cross-coupling reaction between 2-arylpyridine and aryltrimethoxysilane in the presence of AgF and BQ in 1,4-dioxane was studied. After various reaction parameters (catalyst, oxidant, additive, solvent and reaction temperature) were examined, the optimal conditions for the reaction were identified. The synthesis is compatible to aryltrimethoxysilane with both electron-withdrawing and electron-donating groups on the aryl moiety with moderate yields. The kinetic isotope effect (k(H)/k(D)) for the C-H bond activation was provided.     

Palladium-catalyzed direct ortho-alkynylation of aromatic carboxylic acid derivatives

The palladium-catalyzed direct alkynylation of C-H bonds in aromatic carboxylic acid derivatives is described. The use of 8-aminoquinoline as a directing group facilitates the alkynylation of an electronically diverse range of C(sp(2))-H bonds.