Cobalt-catalyzed low pressure double carbonylation of aryl and secondary benzyl halides

α-Ketoacids can be easily synthesized with satisfactory yields and selectivities by carbonylation of aryl halides and secondary benzyl halides under very mild conditions. The reactions are catalyzed by Co₂(CO)₈ in alcoholic solvents; the presence of a methyl source (dimethyl sulfate or methyl iodide) is necessary for the carbonylation of the aryl halides. Base, temperature and solvent have large effects on the course of the reaction.     

Intermediates of the PTC carbonylation of benzyl halides by cobalt carbonyls, II

The structures of intermediates in the PTC carbonylation of two fluorinated benzyl halide substrates were studied. X-ray crystal and molecular structure of 2- and 3-fluorobenzylcobalt tricarbonyl triphenylphosphine derivatives was determined. The supposed influence of structural parameters on the reactivity is discussed.     

One-pot amide synthesis from allyl or benzyl halides and amines by Pd-catalysed carbonylation

Amides can be prepared from allyl or benzyl halides and primary or secondary amines, using Pd(0) catalyst under CO pressure, in a one-pot synthesis. The reaction proceeds through the acyl palladium halide formation which undergoes an acylic nucleophilic substitution from the amine.     

Mechanism of the catalytic carbonylation of aryl halides with a modified cobalt carbonyl

Investigation of the mechanism of the carbonylation of aryl halides in a catalytic system consisting of cobalt carbonyl, terminal olefin oxide, and base showed that this catalytic system activates aryl halides via a radical anion mechanism. The kinetic regularities of the process together with IR spectral data suggest reversible formation of the active catalytic complex under the reaction condition. The complex is a cyclic metal lactone, and it can form not only from olefin oxide but also from its methanolysis product, the corresponding glycol monomethyl ether.     

Catalytic systems for carbonylation of aryl halides

Data on the structure and reactivity of the catalytic systems used in the synthesis of arenecarboxylic acids by carbonylation of aryl halides are summarized. Comparative analysis of the catalytic systems on the basis of palladium and cobalt complexes in terms of the mechanism of their action, range of substrates, and synthetic uses is performed. Different aspects of the cobalt-catalyzed carbonylation of aryl halides (activity of the catalytic system, reaction chemo-and regioselectivity) from the viewpoint of the radical anion mechanism of activation of aryl halides are considered.     

Reaction of red phosphorus with benzyl halides in a superbase system

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, p. 488, February, 1989.     

Reaction of sulfur with benzyl halides

Conclusions The main products of the reaction of benzyl chloride and benzyl bromide with sulfur at 230°C are tetraphenylthiophene, 2-phenylthianaphthene, E-stilbene, dibenzyl, and 2-phenyl-3-benzylthianaphthene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 653–654, March, 1989.     

An efficient catalytic system for the synthesis of glycerol carbonate by oxidative carbonylation of glycerol

Glycerol carbonate was synthesized by the oxidative carbonylation of glycerol catalyzed by the commercial Pd/C with the aid of NaI.High conversion of glycerol(82.2%),selectivity to glycerol carbonate(>99%),and TOF(900 h–1)were obtained under the conditions of 5 MPa(pCO:pO2=2:1),140 oC,2 h.The highly active palladium species were generated in situ by dissolution from the carbon support and stabilized by re-deposition onto the support surface after the reaction was finished.Palladium dissolution and re-deposition were crucial and inherent parts of the catalytic cycle,which involved heterogeneous reactions.This Pd/C catalyst could be recycled and efficiently reused for four times with a gradual decrease in activity.Moreover,the influences of various parameters,e.g.,types of catalysts,solvents,additives,reaction temperature,pressure,and time on the conversion of glycerol were investigated.A reaction mechanism was proposed for oxidative carbonylation of glycerol to glycerol carbonate.     

An efficient palladium catalytic system for microwave assisted cyanation of aryl halides

Application of a new catalytic system for cyanation reaction of various aryl halides using K₄[Fe(CN)₆] as cyanating source was examined. The reactions were performed under microwave irradiation and results showed that application of this catalytic system and DMF at 130 °C minimized the reaction times from hours to minutes in good to excellent yields.     

Iodide ion promotion of benzyl chloride-borate ester carbonylation reactions

Esters are isolated in fine yields from the rhodium(I) catalyzed reaction of benzyl chlorides with borate esters and carbon monoxide, in the presence of potassium iodide.     

Oxidation of benzyl alcohols, benzyl halides, and alkylbenzenes with oxone

Oxidation of benzyl alcohols, benzyl halides, and alkylbenzenes to their corresponding oxidation products has been shown to be accomplished directly with oxone. The methodology that involves mere stirring/heating of the reactants and oxone in acetonitrile/water (1:1, v/v) is simple and practical, but is limited to substrates that do not contain sensitive functionalities and heteroaromatic rings.     

Effective synthesis of benzyl halides triggered by in situ prepared hypervalent halides

An effective approach for the direct benzylhalogenation with in situ generation of hypervalent halides has been developed.A variety of benzyl halides are produced in moderate to excellent yields(up to 99%) with high regioselectivities.UV absorption spectrum is employed to detect the formation of ferr-butyl hypoiodite.     

A simple catalyst system for the palladium-catalyzed coupling of aryl halides with terminal alkynes

A convenient catalyst system consisting of Pd(OAc)₂, PPh₃, K₃PO₄ and DMSO was found to be effective for the coupling reaction of aryl halides with terminal alkynes as well as the deacetonative coupling reaction using a 4-aryl-2-methylbut-3-yn-2-ol as a terminal alkyne precursor. An iminophosphine as a ligand worked more effectively for some combination of substrates than triphenylphosphine.     

Aminocarbonylation of aryl halides using a nickel phosphite catalytic system

The nickel and phosphite catalytic system with sodium methoxide enables a very efficient aminocarbonylation reaction to be performed between aryl iodides or bromides and N,N-dimethylformamide (DMF). Phosphite ligand 1, which is very stable to air and moisture and, furthermore, inexpensive, afforded the highest reaction yield.     

New method for the catalytic dehalogenation of aromatic halides

Translated from Izvesftiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 492–493, February, 1988.     

Palladium-catalyzed cross-coupling of benzyl thioacetates and aryl halides

A method for preparing benzyl aryl thioethers utilizing an in situ deprotection of benzyl thioacetates as an alternative to free thiols as starting materials has been developed and optimized. Good to excellent yields of diverse benzyl aryl thioethers are obtained with air-stable, odor-free, and easy to prepare thioesters. A one-pot protocol for forming benzyl aryl thioethers from a benzyl halide, potassium thioacetate, and an aryl bromide has also been demonstrated.     

One carbon homologation of halides to benzyl ethers

The preparation of one carbon homologated benzyl ethers from alkyl and aromatic halides is reported. The coupling reaction is rapid and efficient at room temperature.     

Contribution of phase transfer to resolve the problem of separation between the catalyst and the product in the catalytic carbonylation of halides.

Study of carbonylation of benzyl bromide in a biphasic liquid-liquid system shows that the catalytic ion pair Bu₄N⁺Co(CO)₄^? stays in the organic layer and that the carbonylated product C₆H₅CH₂CO₂^? stays in the aqueous one.     

In situ generation of the Coates catalyst: a practical and versatile catalytic system for the carbonylation of meso-epoxides

A highly active catalytic system for the carbonylation of meso- and terminal epoxides to β-lactones is described. The active catalyst, analogous to Coates' catalyst, is generated in situ from commercially available (TPP)CrCl and Co(2)(CO)(8). This practical system circumvents the preparation of air sensitive cobaltate salts, operates at low catalyst loadings, and allows the carbonylation of functionalized, sterically demanding and heterocyclic meso-epoxides.