Palladium-catalyzed reduction of olefins with triethylsilane

The versatility of the palladium(II) chloride and triethylsilane system has been tested in the hydrogenation of 1-alkenes. The reduction of 1-alkenes was carried out in the presence of triethylsilane, ethanol and a catalytic amount of palladium(II) chloride, at room temperature. This facile and efficient method affords high yields for hydrogenation of unsaturated alkenes to the corresponding alkanes.     

Palladium-catalyzed homocoupling of aryl halides in the presence of fluoride

This report describes the fluoride-mediated homocoupling of aryl iodides and bromides catalyzed by palladium(0). This coupling protocol is tolerant of electron-donating and electron-withdrawing substitutents on the aryl halide, as well as ortho substitution. Optimum reaction conditions entail 10 mol% Pd(dba)₂, 3 equiv of tetrabutyl ammonium fluoride (TBAF) in DMF at 90 °C.     

Palladium-catalyzed carbonylation of chlorobenzene in the presence of lewis acids

Carbonylation of chlorobenzene to 4-chlorobenzophenone and/or benzoyl chloride may be catalyzed by PdCl₂ in the presence of Lewis acids MCl₃ (M=Al, Ga). Such a C−Cl bond carbonylation with a phosphine-free catalyst was previosly unknown.     

Palladium-catalyzed hydroesterification of styrene derivatives in the presence of ionic liquids

The palladium-catalyzed hydroesterification of olefins occurs efficiently in a range of ionic liquid media. Selectivities ranging from 5-7:1 for the linear ester were obtained with styrene in a range of IL solvents. The use of ILs allowed the catalyst to be easily separated from the organic product by either extraction or distillation. The (Ph₃P)₂PdCl₂ precatalyst could be recovered unchanged from the ionic liquid phase. The IL/catalyst phase could be recycled five times with an average yield of 68%.     

Palladium-catalyzed cyclization of alkenyl beta-keto esters in the presence of chlorotrimethylsilane

PdCl2(CH3CN)2 catalyzed the cyclization of alkenyl beta-keto esters in the presence of a stoichiometric amount of SiMe3Cl to form 2-carboalkoxycyclohexanones in good yield with excellent regioselectivity.     

Photooxidation of aryl alkanes by a decatungstate/triethylsilane system in the presence of molecular oxygen

Decatungstate photocatalyzes the oxidation of aryl alkanes to the corresponding tertiary hydroperoxides and alcohols, in the presence of molecular oxygen. The addition of triethylsilane to the reaction mixture substantially increases the proportion of hydroperoxide formed.     

Palladium-catalyzed asymmetric allylic substitutions in the presence of chiral phosphine-imine type ligands

Chiral bidentate phosphine-imine type ligand L9 is fairly effective in the asymmetric allylic substitution of 1,3-diphenylpropenyl acetate with dimethyl malonate to give the corresponding adduct in moderate yield and good ee.     

Reaction of oxygen-containing monomers with triethylsilane in the presence of iron,manganese, and rhenium carbonyls

A study was carried out on the reaction of triethylsilane (TES) with acrolein, the diethyl acetal of acrolein, and allyl alcohol in the presence of Fe(CO)₅ Mn₂ (CO) ₁₀,and Re ₂ (CO) ₁₀.Acrolein reacts with TES in the presence of Fe(CO)₅ to give the 1,4-addition product in high yield. The reaction of the diethyl acetal of acrolein largely features cleavage of the C- O bond and formation of Et₃SiOEt.Allyl alcohol reacts with TES in the presence of Fe(CO)₅, Mn₂ (CO) ₁₀,and Re₂ (CO) ₁₀ to give the dehydrocondensation product, namely, triethylallyloxysilane, which undergoes hydrogenation and hydroxylation to give triethylpropyloxysilane and -(triethylsilyloxy)propyltriethylsilane, respectively. The yields of these products depend on the metal carbonyl used.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 483–485, February, 1990.     

Reaction of triethylsilane with propargyl chloride in the presence of the H2PtCl6-I2 catalytic system

Conclusions The major product of the reaction of triethylsilane with propargyl chloride in the presence of the H₂PtCl₆-I₂ catalytic system is triethyl(3-chloropropyn-1-yl)silane. Triethylchloro, triethyl(propen-2-yl)triethyl(propen-1-yl)-, triethyl(propyn-1-yl)-, and triethyl(propadienyl)silanes are also formed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2137–2138, September, 1986.     

Free-radical chain dechlorination of chloroethanes in liquid triethylsilane

The kinetics and mechanism of the free-radical chain dechlorination of C₂Cl₆, C₂Cl₅H, and sym-C₂Cl₄H₂ in Et₃SiH wereinvestigated over a wide temperature range. The propagation step of the dechlorination of chloroethanes (C₂Cl_x H_6?x) proceeds by the following reactions: Analysis of the temperature dependence of product formation gave the Arrhenius expressions for k₄/k₃ which in turn were utilized for the estimation of the absolute Arrhenius parameters for hydrogen abstraction from Et₃SiH. Our results show that the values of E_abs are lower in Et₃SiH than in c-C₆H₁₂ by about 2–3 kcal/mol, while the A factors are almost equal. In competitive studies k₂ was determined versus Br abstraction from n-C₅H₁₁Br. The relative Arrhenius parameters determined by this method show that variations in both A factors and activationenergies are responsible for the reactivity trends observed in the Cl transfer reactions of Et₃Si radicals.     

Palladium-catalyzed highly regio- and stereoselective addition of organoboronic acids to allenes in the presence of AcOH

The Pd(0)-catalyzed regio- and stereoselective addition of organoboronic acids to allenes leads to stereodefined tri- or tetrasubstituted alkenes. Furthermore, this method shows high substitutent-loading capability and tolerance of various substitutents. A hydropalladation-Suzuki coupling mechanism, which may account for the regio- and stereoselectivity, is proposed.     

Palladium-catalyzed oxidation of lower aliphatic alcohols with oxygen in the presence of aromatic nitriles in aqueous medium

The kinetics of oxidation of lower aliphatic alcohols (C₁–C₄) to the corresponding carbonyl compounds with oxygen in the presence of palladium(II) tetraaqua complex and aromatic nitriles (benzonitrile, phenylacetonitrile, and o-tolunitrile) in aqueous medium (c = 0.01 M) at 65°C under atmospheric pressure were studied. A probable reaction mechanism and kinetic equation were proposed. Aromatic nitriles were found to stabilize decomposition of low-valence palladium species, ensuring activation of molecular oxygen and subsequent oxidation of alcohols.     

Palladium-catalyzed Suzuki cross-coupling of aryl halides with aryl boronic acids in the presence of glucosamine-based phosphines

Carbohydrate-substituted phosphines are easily obtained in quite good yields by coupling of protected or non-protected d-glucosamine with the corresponding diphenylphosphino acid. These neutral ligands, in association with palladium acetate, are very active catalysts in the Suzuki cross-coupling reaction. The polyhydroxy phosphines are more active than the peracetylated phosphines. The process tolerates electron-rich as well as electron-poor substituents. Excellent turnovers, up to 97?000 are observed.     

Reaction of triethylsilane with aromatic azomethines

Conclusions A correlation was established between the reaction rate constant and the Hammett constants of the substituents X for the reactions of Et₃SiH with aromatic azomethines PhCH =NC₆H₄X in the presence of (Ph₃P)₃PhCl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 460–462, February, 1978.See [1] for previous communication.     

Palladium-catalyzed, one-pot carbonylation of heterocyclic compounds into their esters, in the presence of mercury salts.

One pot carbonylation of thiophene, furan, benzofuran and pyrrole in alcohol, to produce the corresponding esters, has been carried out at room temperature, using a PdCl₂/mercury salt/Copper(II) system.     

Pulse radiolysis and product analysis of triethylsilane in methanol

The transients resulting from triethylsilane (R₃SiH) in airfree high purity methanol were studied by pulse radiolysis. Their total absorption spectrum shows a maximum at 265 nm (ϵ₂₆₅ = 5300 dm³mol⁻¹cm⁻¹) and disappears by a second order reaction with a rate constant of 2k = 9.3±10⁹dm³mol⁻¹s⁻¹. R₃SiH reacts with solvated electrons (e^-_s) in methanol with k = 9.2±0.2) × 10⁸dm³mol⁻¹s⁻¹. The R₃S̊i radicals react selectively and efficiently with the CH₃O̊ and C̊H₂OH species resulting in the formation of triethylmethoxysilane (R₃Si-OCH₃) and triethylsilylmethanol (R₃Si-C̊H₂OH), respectively. R₃Si-OC̊H₃ is subsequently converted into various final products which were identified and their yields determined. A reaction mechanism is suggested for the explanation of the rather complicated reactions pathways.