From aryl iodides

Carboxylic adds are obtained from aryl iodides by the reaction of chloroform under basic conditions without using CO[336],... 

The palladium-catalyzed carbonylation of aryl halides in the presence of various nucleophiles is a convenient method for synthesizing various aromatic carbonyl compounds (e.g., acids, esters, amides, thioesters, aldehydes, and ketones). Aromatic acids bearing different aromatic fragments and having various substituents on the benzene ring have been prepared from aryl iodides at room temperature under 1 atm... 

The Alper group [163] reported on a highly efficient double carbohydroamination for the preparation of a-amino carboxylic acid amides 6/1-345, starting from aryl iodides and a primary amine 6/1-344, in usually high yield (Scheme 6/1.88) both, aryl iodides with electron-donating and electron-withdrawing groups can be used. 

A somewhat related process, the cobalt-mediated synthesis of symmetrical benzo-phenones from aryl iodides and dicobalt octacarbonyl, is shown in Scheme 6.49 [100]. Here, dicobalt octacarbonyl is used as a combined Ar-I bond activator and carbon monoxide source. Employing acetonitrile as solvent, a variety of aryl iodides with different steric and electronic properties underwent the carbonylative coupling in excellent yields. Remarkably, in several cases, microwave irradiation for just 6 s was sufficient to achieve full conversion An inert atmosphere, a base or other additives were all unnecessary. No conversion occurred in the absence of heating, regardless of the reaction time. However, equally high yields could be achieved by heating the reaction mixture in an oil bath for 2 min. 

Removal of the iodine atom from aryl iodides proceeds smoothly in a DMF-Bu4NCl04-(Hg) system [561, 562]. A Cd-modified electrode-assisted allylation of aldehydes and ketones has been attained in a DMF-Et4NCl04 system, in which the... 

The Rongalite method (see Section 3.1.1.1b,i) can be successfully applied to the preparation of diaryl tellurides from aryl iodides. This method seems to be advantageous compared to the preceding one because of the higher yields and milder experimental conditions. 

The electrochemical allylation of carbonyl compounds by electroreductivc regeneration of a diallyltin reagent from allyl bromide and a Sn species leads to formation of homoallylic alcohols in yields of 70-90 % even in methanol or methanol/water (Table 7, No. 12) Bisaryl formation is possible also from aryl iodides or bromides in the presence of electro-generated Pd phosphane complexes (Table 7, No. 13) In the presence of styrenes, 1,3-butadienes, or phenyl acetylene the products of ArH addition are formed in this way (Table 7, No. 14) . The electroreductivc cleavage of allylic acetates is also possible by catalysis of an Pd°-complex (Table K No. 15)... 

R is usually aryl or vinylic.1627 The formation of a-keto acids1628 or esters1629 requires more severe conditions. a-Hydroxy acids were obtained from aryl iodides when the reaction was carried out in the presence of an alcohol, which functioned as a reducing agent.1630 Cobalt catalysts have also been used and require lower CO pressures.1625 OS V, 20, 739. 

Access to the 1,3-benzazepinone 39 has been achieved from aryl iodide 38 with a Pd(0) catalyst, followed by cyclization of the intermediate palladium complex upon reaction with thallium acetate, thus providing a convenient approach to the fused seven-membered ring system (Equation 5) <1998ICA(270)123>. 

In the atom-transfer reactions of iodine from aryl iodides to phenyl radical, intervention of [9-1-2] aryl(phenyl)-A3-iodanyl radicals is proposed [Eq. (86)] [3]. The ab initio molecular orbital study indicates that the diaryl-A3-iodanyl radicals are transition states in the atom-transfer reactions, but not intermediates [161]. Examples obtained by ab initio molecular orbital calculations with the B3LYP/6 - 31G(d) level are shown in Fig. 2. 

Fig. 2. Predicted coordinates for atom-transfer of iodine from aryl iodides to phenyl radical...

In order to prepare the bicyclic compound 9, an intramolecular Heck reaction under Grigg s conditions (Pd(OAc)2, K2CO3, Bu4NBr) is carried out (see Chapter 13).7 Starting from aryl iodide 8 a six-membered ring formation occurs providing intermediate 28, which reacts to alkene 29. Finally double bond isomerization to compound 9 is forced by the formation of a thermodynamically more stable enol ether. 

Scheme 2 Preparation of primary benzamides from aryl iodides and bromides by in situ carbonylation...

This form of active zinc prepared in the presence of an electron carrier can readily form arylzinc iodides at room temperature from aryl iodides. Aryl bromides reacted far more efficiently with reduced reaction times at refluxing temperatures. The newer two-pot lithium reduction procedures for the preparation of active zinc requires 3-4 h for a total preparation time. Whilst the old one-pot preparation of active zinc from the reduction of zinc salts with lithium... 

Recently, a bifunctional, silica gel-supported catalyst, containing an alkaloid ligand 14d and a palladium(0)complex, was applied to the dihydroxylation of disubstituted alkenes formed in situ from aryl iodides and terminal alkenes in a single-pot procedure [72]. 

Ullmann reaction (4, 33 6, 654). The nickel species generated from NiBri and zinc in HMPT is an effective catalyst for the preparation of biaryls from aryl iodides. An excess of zinc is generally helpful potassium iodide exerts a favorable effect. The reaction is conducted at 40-70° for 3-30 hours. Yields are >90% for iodobenzene itself and are also similar for para- and me/a-substituted derivatives. Yields are lowered by the presence of ort/io-substituents. 

Note that seleno esters (ArCOSeAr) were prepared from aryl iodides, CO, PhSeSnBua, and a palladium catalyst. ... 

Simple alkyl bromides or chlorides do not react with Hg on irradiation, and only low yields of ArHgl are obtained from aryl iodides . Diiodomethane reacts with Hg metal on irradiation in PhH to give both IHgCH2l and CH2(HgI)2 . ... 

Castro, C. E., Stephens, R. D. Substitutions by iigands of iow vaient transition metals. A preparation of tolans and heterocyclics from aryl iodides and cuprous acetyiides. J. Org. Chem. 1963, 28, 2163. 

Palomo, C., Oiarbide, M., Lopez, R., Gomez-Bengoa, E. Phosphazene bases for the preparation of biaryl thioethers from aryl iodides and arenethiols. Tetrahedron Lett. 2000,41, 1283-1286. 

Palladium, in the form of palladium(II) acetate, has also been used to catalyze biaryl formation directly from aryl iodides (R3N 100 °C), especially P-NO2 and p-Cl derivatives. As usual, ortho substituents severely hinder this type of coupling. Related reductive couplings of aryl halides have been achieved using hydrazine and a Pd-Hg catalyst, electrochemically generated Pd° catalysts, or a palladium on carbon catalyst in the presence of aqueous sodium formate, sodium hydroxide and, crucially, a catalytic amount of a surfactant. The first two procedures look to be particularly selective and efficient, while the latter, rather different, method is not so efficient but does look amenable to large scale work. 

In addition to reactions initiated with copper metal, reactions have been conducted with copper salts, such as copper oxides, alloys and coordination complexes. Reactions with many bases in several polar solvents have also been explored. Diphenylamine and o-bromonitrobenzene couple with stoichiometric amounts of copper(I) oxide and copper(I) bromide in DMA (equation 59)234. The synthesis of triaryl amines from aryl iodides and arylamines in one-pot proceeds in the presence of Cul and potassium tart-butoxide at 135 °C235. The highest yields were obtained with aryl iodides and electron-rich arylamines. 

An excellent preparation of diaryl sulfides from aryl iodides and arenethiolate ions has been devised. Photolysis brings about rapid formation of the sulfide by a radical-chain process. Yields of isolated product seldom fall below 75%, Eq. (28). This ap-... 

Arylphosphonate esters are conveniently prepared from aryl iodides and potassium dialkyl phosphites on photolysis in ammonia, Eq. (29). Isolated yields of products containing methyl, methoxy, trifluoromethyl or halogen substituents range from 87 to... 

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