Iodobenzene carbonylation reaction

Satoh T, Kokubo K, Miura M et al (1994) Effect of copper and iron cocatalysts on the palladium-catalyzed carbonylation reaction of iodobenzene. Organometallics 13 4431 1436... 

Arylbenzothiazoles (384) can be obtained from o-aminothiophenol and iodobenzenes in a palladium-catalyzed carbonylation reaction (Equation (78)) <940M3346>. 

Tanaka and his associates demonstrated for the first time how to use non-volatile ionic liquids (ILs) as solvents in palladium-catalyzed carbonylations [163], In the case of alkoxycarbonylation of bromobenzene, higher yields were obtained when 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] was used as the reaction medium compared with standard conditions. And the selectivity for the monocarb-onylation of iodobenzene with t -PrOH or Et2NH was significantly enhanced by [bmim][BF4]. After separation of the products, the solvent-catalyst system was easily recycled and exhibited catalytic activity up to seven times. Since then the replacement of traditional solvents with quaternary ammonium halides, imidazoli-um- or pyridinium-derived ILs has gained increasing importance [164—173]. Recently, the phosphonium salt IL trihexyl(tetradecyl)phosphonium bromide has proven to be an effective reaction medium for various carbonylation reactions of aryl and vinyl bromides or iodides under mild conditions (Scheme 2.17) [174]. 

However, gas substrates such as carbon monoxide (CO) can be easily introduced in a packed-bed reactor. ThanesNano researchers reported aminocarbonylation of aryl halides with amines and CO gas at high pressure and high temperature under flow conditions, which afforded the corresponding amides in moderate-to-high yield (Scheme 7.24) [101]. In this paper, they described that reaction parameters (solvent, base, catalyst, pressure, temperature, and so on) were rapidly optimized in the reactions, which required less than 2 min. As a continuous study, the authors reported a double carbonylation reaction of iodobenzene to give a-ketoamides in a flow reactor [102]. 

A nickel(II) species is also though to be an intermediate in the carbonyla-tion reaction of iodobenzene with (V-methylbenzaldimine and nickel carbonyl. Two addition modes of an ensuing aroylnickel(II) complex to the C=N double bond can be envisaged as routes to l-methyl-2-phenylindol-3-one and an ethylenediamine derivative (Scheme 47).7 5 The scope of this simple indole synthesis has not been assessed. 

Additional examples of palladium-catalyzed cross-couplings, in particular with allenylzinc compounds, can be found elsewhere [11, 15, 36]. A systematic study comparing several chiral palladium phosphine catalysts in the reaction of 4,4-di-methyl-1,2-pentadienylzinc chloride and iodobenzene revealed that an enantiomeric excess of only 25% was obtained from the best catalyst combination PdCl2 and (R,R)-DIOP [15]. The synthetic value of these transformations of donor-substituted allenes as precursors is documented by the preparation of a/l-unsaturatcd carbonyl... 

An a-allenic sulfonamide undergoes Pd-catalyzed carbonylative cyclization with iodobenzene, affording a mixture of isomeric heterocycles (Scheme 16.12) [17]. The coupling reaction of an allene with a PhCOPdl species takes place at the allenyl central catrbon to form a 2-acyl-Jt-allylpalladium complex, which is attacked by an internal sulfonamide group in an endo mode, affording a mixture of isomeric heterocycles (Scheme 16.13). 

Several examples have been reported of the use of palladium-mediated oxidation reactions of alcohols and alkyl halides. Palladium(II) acetate in the presence of iodobenzene converts primary and secondary alcohols into carbonyl compounds under solid-liquid two-phase conditions [20], However, other than there being no further oxidation to carboxylic acids, the procedure has little to commend it over other methods. It is relatively slow with reaction times in the order of 2 days needed to achieve yields of 55-100%. 

Carbonylative coupling of iodobenzene with 2-methyl-3-butyn-2-ol under 65 bar carbon monoxide afforded phenylfuranones (double carbonylation) in reasonable yields (Scheme 6.32) [69]. The reaction is thought to proceed through the formation of a benzoylpalladium intermediate which either reacts with the alkynol or liberates benzoic acid hence the formation of considerable amounts of the latter. 

The step common to both of these reactions is electrophilic attack of a hypervalent iodine species at the a-carbon of the carbonyl compounds to yield an intermediate 3. Nucleophilic attack of methoxide ion or tosy-loxy ion with the concomitant loss of iodobenzene results in a-functionalized carbonyl compounds (Scheme 2). 

The double carbonylation of iodobenzene with diethylamine catalyzed by Pd(OAc)2-PPh3 was carried out in l-butyl-3-methylimidazolium tetrafluoroborate 315 as reaction medium at 80 °C and 38 atm of CO to give phenyl-glyoxamide 314 as the predominant product (83%) accompanied by benzamide 313 (17%) (Equation (29)). The use of ionic liquids showed the same reactivity and product selectivity as those using diethylamine as solvent for this reaction, while separation of products and recycling of the catalyst was easier. ... 

Values of rate constants in reaction (18 a) have been calculated (40) by means of this and similar treatments for a-ketoacids (44, 45), pyri-dinecarboxylic acids (46, 47), unsaturated acids (48, 49), phthalic acid (50), carbonyl compounds (51,52), iodobenzenes bearing ionisable groupings (53), etc. 

A remarkable dual way to obtain PhI(02CCF3)0I(02CCF3)Ph involved either solvolysis of iodosylbenzene by trifluoroacetic acid or nucleophilic attack by a strong base to the carbonyl group of [bis(trifluoroacetoxy)iodo]benzene [49]. Another unusual reaction leading to the formation of the same iodane has been reported between iodobenzene and xenon bistrifluoroacetate [50]. 

In addition to allylic alcohols, other unsaturated alcohols react with halides to give carbonyl compounds. Although the reaction was slow (three days), the reaction of 10-undecen-l-ol (50) with iodobenzene afforded the aldehyde 52 in a high yield. In this... 

Benzyl halides have been reported to react with nickel carbonyl to give both coupling and carbonylation (59). Carbonylation is the principal reaction in polar nonaromatic solvents, giving ethyl phenylacetate in ethanol, and bibenzyl ketone in DMF. The reaction course is probably similar to that of allylic halides. Pentafluorophenyl iodide gives a mixture of coupled product and decafluorobenzophenone. A radical mechanism has been proposed (60). Aromatic iodides are readily carbonylated by nickel carbonyl to give esters in alcoholic solvents or diketones in ethereal solvent (57). Mixtures of carbon monoxide and acetylene react less readily with iodobenzene, and it is only at 320° C and 30 atm pressure that a high yield of benzoyl propionate can be obtained (61). Under the reaction conditions used, the... 

For the Heck reaction as discussed in Section III.2.1 the final position of the olefi-nic double bond of the products must not necessarily be the same as in the starting materials (for example Schemes 8, 9, and 10 of Section III.2.1) [1], The selectivity is often driven by stereochemical requirements, because the /1-hydrogen elimination step which forms the double bond proceeds exclusively in a syn manner (if a trans /3-hydrogen is eliminated, one should suspect major deviations from the general mechanism of the Heck reaction, for example electrophilic substitution instead of carbopalladation). An impressive example of a double bond migration is depicted in Scheme 1 - instead of olefins the coupling reaction of iodobenzene 1 with the olefmic alcohol 2 results in the isomeric aldehydes 3 and 4 as final products [2], Reactions of this type have emerged as valuable tools for the synthesis of carbonyl compounds and also as crucial steps in domino processes. 

However, for other palladium catalysed reactions of organozinc iodides with electrophiles, THF is a good choice of solvent. The incompatibility of THF and acid chlorides at ambient temperature can also be overcome, in some cases, by the use of a carbonylative cross-coupling in which an iodobenzene derivative is used as the precursor.17... 

The same reaction was also investigated using the palladium-carbene complex, 58, as catalyst (Scheme 9.12).1401 Of the different ionic liquids studied, tetrabutylammonium bromide gave by far the best results while imidazolium based solvents afforded only poor conversions. At atmospheric pressure, only iodobenzene was carbonylated. The conversion of less reactive arylhalides not only required higher CO-pressures, but also the addition of a phosphine ligand. Reuse of the catalyst after extraction of the product with diethyl ether was possible for at least 6 runs with only a moderate decrease in activity. 

Unsymmetrical diaryl ketones are obtained by the reaction of iodobenzene with nickel carbonyl in the presence of an organomereury halide ... 

Diaryliodonium salts react more or less easily with carbonyl compounds to afford the C-arylated derivatives. Depending upon the nature of the substrate, different experimental conditions have been used. These reactions are generally performed in alcoholic solvents (r-BuOH, r-AmOH.) or in DMF, at temperatures ranging from low (- 78°C) to reflux of the solvent. Arylation of simple ketones has been obtained either by reaction of the ketone enolates with an appropriate diaryliodonium salt, i or by reaction of the ketone enol silyl ether with diaryliodonium fluoride. Phenylation of the potassium enolate of acetone (13) with diphenyliodonium bromide (14) afforded a modest yield of the monophenylation product, but the stimulation with solvated electrons led to overreaction due to the subsequent reaction of the iodobenzene, a good SrnI arylating agent under these conditions. 9... 

Ruthenium complexes catalyze the reaction of primary alcohols with o-phenylenediamine. The catalyst apparently has dual roles in promotion of cyclization and oxidation of the alcohol to aldehyde <91CL1275>. A novel palladium-catalyzed carbonylation of iodobenzene has been linked to base-induced coupling and cyclization with o-phenylenediamine to give 2-arylbenzimidazoles without having to use an arylcarboxylic acid (Scheme 152) <93JOC7016>. 

Reactions can also be carried out in microemulsions. (Microemulsions have finer droplets of the oil phase than the usual emulsions.) They have been used in the hydroxy-carbonylation of iodobenzene (8.34).245... 

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