Synthesis of heteroaromatic carboxylic acids by carbonylation of hetaryl halides with catalysts based on cobalt carbonyl modified with epoxides

A new method for the synthesis of heteroaromatic acids and their derivatives (esters and salts) by carbonylation of the corresponding halides was developed. Hetaryl halides were activated in alcoholic-alkali medium by highly active catalytic systems based on cobalt carbonyl modified with epoxides, developed previously for carbonylation of aryl halides.     

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.     

A versatile procedure for synthesis of organic acids by cobalt carbonyl catalyzed carbonylation of organic halides

A versatile procedure for synthesis of a broad range of fatty-aromatic and aromatic acids by carbonylation of the corresponding halides under very mild conditions in the presence of cobalt carbonyl as a catalyst was suggested. The main principles of a flexible process for production of practically significant acids and their derivatives were developed.     

Cobalt carbonyl catalyzed sRN1 carbonylation of aryl and vinyl halides by phase transfer catalysis

The phase transfer catalyzed, cobalt carbonyi catalyzed carbonylation (1 atm. P.) of aryl and vinyi bromides under photostimulation (350 nm) affords the corresponding unsaturated acids in high yield.     

Palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate

Highly efficient palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate is reported. This procedure does not use carbon monoxide and affords one-carbon-elongated carboxylic acid phenyl esters in excellent yields. The reaction proceeds smoothly under mild conditions and tolerates a wide range of functional groups including aldehyde, ether, ketone, ester, and cyano groups. Furthermore, a variety of heteroaromatic bromides can be converted to the corresponding phenyl esters in high yields.     

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.     

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.     

C-H arylation of unactivated arenes with aryl halides catalyzed by cobalt porphyrin

A general procedure for cobalt-catalyzed direct C-H arylation of unactivated arenes has been discovered. This method employs aryl halides as the direct coupling partners with arenes without using any Grignard-type reagents. This catalysis opens a new methodology for the preparation of symmetrical as well as unsymmetrical biaryls in a user-friendly approach.     

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.     

Carboxylic acid anhydrides via Pd-catalyzed carbonylation of aryl halides at atmospheric CO pressure

A convenient method has been developed, which allows for the direct transformation of aryl iodides into the corresponding carboxylic acid anhydrides via Pd-catalyzed carbonylation under atmospheric CO pressure.     

tert-Butoxide-mediated arylation of benzene with aryl halides in the presence of a catalytic 1,10-phenanthroline derivative

Sodium tert-butoxide mediates the coupling of aryl halides with benzene derivatives without the aid of transition metal catalysts but with a catalytic 1,10-phenanthroline derivative.     

Mechanism of the electrochemical conversion of aryl halides to arylzinc compounds by cobalt catalysis in DMF/pyridine

The study of the electrochemical behavior of cobalt bromide, CoBr2, in the presence of zinc bromide, ZnBr2, and aryl halides, ArX, in a dimethylformamide (DMF)/pyridine (9:1, v/v) mixture allowed us to complete the study of the mechanism of the electrochemical conversion of aryl halides into arylzinc compounds by using cobalt catalysis. The last step of the catalytic process has been shown to be a transmetalation reaction between the arylcobalt(II) species and zinc ions that regenerates the cobalt(II) catalyst. The effect of zinc bromide on each step of the catalytic cycle has been studied. It is especially shown that the presence of ZnBr2 stabilizes the electrogenerated Co1 but has no effect on the rate constant of the oxidative addition of aryl halides, ArX, to Co1. Rate constants for the disproportionation reaction of Co1 and the oxidative addition have been determined in the presence of ZnBr2 and compared with the values obtained in its absence.     

Palladium-catalysed coupling of terminal alkynes with aryl halides aided by catalytic zinc

The palladium-catalysed coupling of aryl halides with terminal alkynes can be performed using base, zinc chloride and sodium iodide. This protocol represents a convenient method for the generation of nucleophilic acetylides in situ.     

No stirring necessary: parallel carbonylation of aryl halides with CO and various alcohols under pressure

The parallel carbonylation of aryl halides with 6-25 bar of CO in 1-mL vials in a standard autoclave was investigated. 4-Bromoacetophenone and 2-chloropyridine were used as model substrates with 102 different O-nucleophiles (primary and secondary alcohols, phenols). No inertization during the loading was necessary. Fifty esters (43 new, yield up to 60%) were isolated and characterized. Ether, ester, ketone, and sometimes even olefin functions were usually tolerated. The new method is suitable for screening and small scale products synthesis.     

New chemical cross-coupling between aryl halides and allylic acetates using a cobalt catalyst

[reaction: see text] The cobalt-catalyzed coupling reaction of aromatic halides and allylic acetates proceeds readily under mild conditions in the presence of the appropriate reducing agent to produce allylaromatic derivatives either in pure acetonitrile (aryl bromides) or in an acetonitrile/pyridine mixture (aryl chlorides).     

Preparation of N-hydroxysuccinimido esters via palladium-catalyzed carbonylation of aryl triflates and halides

N-Hydroxysuccinimido esters of aromatic carboxylic acids (a.k.a. active esters) can be made using a potentially general, one-step procedure via Pd-catalyzed carbonylation of an aryl triflate or aryl iodide with CO and N-hydroxysuccinimide. Excellent yields (up to 94%) were observed when the reaction was done in DMSO at 70°C and 1 atmosphere of CO pressure.     

Carbonylation of chlorobiphenyls catalyzed by modified cobalt carbonyl

Dichlorobiphenyls having both chlorine atoms in the same benzene ring undergo mild carbonylation in the presence of 1,2-epoxypropane-modified carbonyl cobalt complex to give biphenylcarboxylic acid esters. Monochlorobiphenyls fail to react under analogous conditions. The rate and selectivity of the reaction depend on the position of chlorine atoms. Carbonylation of dichlorobiphenyls having a chlorine atom in the meta position occurs preferentially at that position. 2,4-Dichlorobiphenyl gives rise mainly to the carbonylation product at the 2-position.     

Palladium/di-1-adamantyl-n-butylphosphine-catalyzed reductive carbonylation of aryl and vinyl halides

A general and efficient palladium-catalyzed reductive carbonylation with low catalyst loadings (0.5 mol % Pd or below) has been developed. The formylation of aryl and heteroaryl bromides proceeds smoothly in the presence of palladium/di-1-adamantyl-n-butylphosphine at ambient pressure of synthesis gas to afford the corresponding aromatic aldehydes in good yields and excellent selectivity. In addition, vinyl halides react under similar conditions to form α,β-unsaturated aldehydes in good yield.