Palladium(0)-catalysed cross-coupling of 2-trimethylsilylpyridine with aryl halides

A general method for the Hiyama coupling reaction between aryl halides and 2-trimethylsilylpyridine has been developed. These conditions have been successfully applied to the synthesis of bis-heteroaryl systems, a key disconnection for the pharmaceutical industry in the synthesis of drug-like molecules.     

Palladium(O) catalyzed azidation and amination of allyl acetates. Selective synthesis of allyl azides and primary allylamines

Palladium catalyzed reaction of allyl acetates with azide ion gives allyl azides, which are readily converted into the corresponding primary allylamines upon treatment with PPh₃/NaOH.     

Palladium catalyzed atom-efficient cross-coupling reactions of triarylbismuths with aryl iodides and aryl triflates

The atom-efficient cross-coupling of triarylbismuths with aryl iodides or aryl triflates using catalytic Pd(OAc)₂/PPh₃ and K₃PO₄ as base in DMF at 90 °C to afford the corresponding functionalized biaryls in high yields is reported.     

Palladium catalyzed atom-efficient cross-coupling reactions of triarylbismuths with aryl bromides

Aryl bromides (3 equiv) were coupled efficiently with triarylbismuths (1 equiv) in an atom-efficient way using the Pd(OAc)₂/PPh₃ catalytic system in the presence of K₃PO₄ as base in DMF at 90 °C, providing excellent yields of the cross-coupled biaryls in short reaction times.     

Palladium pincer complex catalyzed substitution of vinyl cyclopropanes, vinyl aziridines, and allyl acetates with tetrahydroxydiboron. An efficient route to functionalized allylboronic acids and potassium trifluoro(allyl)borates

Palladium-catalyzed boronation of vinyl cyclopropane, vinyl aziridine, and allyl acetate substrates could be accomplished using tetrahydroxydiboron reagent in the presence of SeCSe pincer complex catalyst 1a. These reactions result in allyl boronic acids, which were converted to synthetically useful trifluoro(allyl)borates or allyl boronates. The catalytic transformations proceed under mild and neutral conditions, and therefore many functionalities Br, COOEt, ArSO2(NH), OAc, and SiRMe2 are tolerated. The selectivity of the presented processes is very high, affording the linear products incorporating a trans double bond.     

Palladium catalyzed thiol cross-coupling of cystein derivatives with aryl and alkenyl halides

Palladium catalyzed cystein thiol cross-coupling reactions with aryl and vinyl halides have been investigated: Pd₂dba₃-CHCl₃ and dppf are the key choice in these reactions. The role of the base in these reactions was also questioned: it has been shown that base can be replaced by an HX-scavenger such as propylene oxide.     

Palladium(0)-promoted cross-coupling of allenylmetal compounds with aryl and vinyl iodides. A novel route to aryl- and vinyl-substituted allenes

The reaction of allenylmetal compounds, RR{′}CCCHM (I), with aryl and vinyl iodides, R I, have been studied. With Pd(PPh₃)₄ as catalyst a highly regioselective formation of allenes, RR{′}CC CHR″ (II), has been observed for MgCl, Cu, Cu_1/2,Li_1/2, Ag, Ag_1/2Li_1/2, or ZnCl, but not Li. The reaction of the iodides proceeds with retention of configuration.     

Palladium pincer complex catalyzed cross-coupling of vinyl epoxides and aziridines with organoboronic acids

Palladium-catalyzed cross-coupling of vinyl epoxides and aziridines with organoboronic acids was performed by using 0.5-2.5 mol % pincer-complex catalyst. The reactions proceed under mild conditions affording allyl alcohols and amines with high regioselectivity and in good to excellent yields. Under the applied reaction conditions aromatic chloro-, bromo- and iodo substituents are tolerated. Our results indicate that the mechanism of the pincer complex catalyzed and the corresponding palladium(0) catalyzed process is substantially different. It was concluded that the transformations proceed via transmetalation of the organoboronic acids to the pincer-complex catalyst followed by an S(N)2'-type opening of the vinyl epoxide or aziridine substrate. In this process the palladium atom is kept in oxidation state +2 under the entire catalytic process, and therefore oxidative side reactions can be avoided.     

Palladium(II)-catalyzed claisen rearrangement of allyl vinyl ethers

The Claisen rearrangement of allyl vinyl ethers is catalyzed by PdCl₂(CH₃CN)₂, provided that alkyl substituents protect the vinyl ether double bond from coordination by the metal catalyst.     

Xantphos as an efficient ligand for palladium-catalyzed cross-coupling reactions of aryl bromides and triflates with allyl acetates and indium

Xantphos was found to be an efficient ligand for palladium-catalyzed allyl cross-coupling reactions of aryl bromides and triflates with allylindium reagents generated in situ from allyl acetates and indium. These reactions occur in high yield with good functional group tolerance.     

Palladium-catalyzed cross-coupling reaction of allyl acetates with pinacol aryl- and vinylboronates

Pinacol boronates 2 couple efficiently with allyl acetates 1 in the presence of a palladium catalyst prepared in situ from PdCl₂ and TFP to give the coupled products 3 in moderate to good yields under mild conditions.     

Palladium(0)-catalyzed allylic alkylation of diketoester-dioxinones with allyl acetates under neutral conditions: synthesis of hexasubstituted benzene derivatives

Intermolecular palladium(0)-catalyzed allylic alkylation of diketoester-dioxinones was performed under neutral conditions with 2-alkenyl and 2-cycloalkenyl acetates. Subsequent aromatization using cesium carbonate gave rise to isopropylidene-protected hexasubstituted resorcylates.     

Palladium pincer-complex catalyzed allylation of tosylimines by potassium trifluoro(allyl)borates

Palladium pincer complex 1 catalyzes the reaction of trifluoro(allyl)borate 2 with a wide range of tosylimines (3) under mild and neutral reaction conditions. This catalytic transformation affords homoallylic amines (4) in good to excellent yield. Mechanistic studies suggest that a transmetalation reaction between complex 1 and the borate salt 2 provides an eta(1)-allylpalladium complex, which subsequently reacts with the imine substrate. [Reaction: see text]     

Radical reactions of butyl mercaptan with vinyl and allyl acetates

Conclusions The reactions of vinyl acetate and allyl acetate with butyl mercaptan in the presence of tert-butyl peroxide and Mn₂(CO)₁₀ lead to an adduct. Acetaldehyde, butyl thioacetate, and the dibutylmercaptal of acetaldehyde are also formed in the case of Mn₂(CO)₁₀.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1418–1421, June, 1989.     

Palladium catalyzed alkynylation of aryl halides (Sonogashira reaction) in water

The palladium catalyzed alkynylation of aryl halides (Sonogashira reaction) has been achieved in pure water without any additives or phase transfer catalysts. The reaction, which requires only 0.5 mol % of Pd(PPh₃)₄ catalyst, is remarkably fast (30 min at 70 °C) producing high yields of the aryl alkyne products.     

Oxidative cross-coupling of allyl(trimethyl)silanes with aryl boronic acids by palladium catalysis

The first oxidative cross-coupling of allylsilanes with aryl boronic acids has been developed by palladium catalysis. The reaction between β-substituted allyl(trimethyl)silanes and a wide range of aryl boronic acids afforded allylarenes in moderate to good yields and excellent selectivity. On the basis of experimental results and literature reports, it was suggested that the reaction might start from transmetalation of aryl boronic acid with AgOAc followed by transmetalation with Pd(II) to give an arylpalladium acetate complex as a key intermediate. This intermediate underwent either electrophilic addition/desilylation or transmetalation with allylsilane and subsequent reductive elimination to give the final product.     

Silver-promoted cross-coupling of substituted allyl(trimethyl)silanes with aryl iodides by palladium catalysis

A ligand-free Pd-catalyzed cross-coupling of substituted allyl(trimethyl)silanes with aryl iodides enabled by silver salts was developed. This reaction delivered allylic arenes chemoselectively and regioselectively. The study suggested that the reaction might proceed through oxidative addition of ArI to Pd(0) followed by halide abstraction to give an electrophilic complex ArPdX, which further reacted with allyl(trimethyl)silanes via electrophilic addition/desilylation/reductive elimination to afford the allyl-aryl coupling products.     

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.