Diaryl iodide

The overall brilliance of the Overman plan was the recognition of just how this nontrivial objective could potentially be accomplished. As shown, assuming that 3 could be converted into a diaryl iodide (i. e. 12), the hope was that this compound could then be coupled to 2 equivalents of stannane 11 through Stille couplings to provide 10. The next operation, however, would be the key... 

An important side reaction is the formation of diaryl methane derivatives ArCHaAr. Moreover poly substituted products may be obtained as minor products. Aromatic compounds have been treated with formaldehyde and hydrogen bromide or hydrogen iodide instead of hydrogen chloride. The formaldehyde may be replaced by another aldehyde the term Blanc reaction however stands for the chloromethylation only. 

Many reactions have been shown to benefit from irradiation with ultrasound (ref. 19). We therefore decided to investigate the effect of ultrasound, different catalysts and the presence of solids on Ullmann diaryl ether synthesis. Indeed, sonication of mixtures of a phenol and a bromoaromatic compound, in the absence of solvent and presence of copper (I) iodide as catalyst and potassium carbonate as base, produces good yields of diaryl ethers at relatively low temperatures (Fig. 10) (ref 20). 

The hydrazone group is hydrolyzed (16-2) during the course of the reaction. Yields are high. Aryl iodides are converted to unsymmetrical diaryl ketones on treatment with aryImercury halides and nickel carbonyl ArH-Ar HgX-l-Ni(CO)4 ArCOAr... 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

Alkylation of 3,5-diaryl-l,2,4-thiadiazoles 22 with trimethylsilylmethyl triflate, in contrast to methyl iodide, occurs at N-2 to afford the salt 23 (Equation 5) and the quaternization at N-2 was confirmed by analysis of the 1SN NMR spectrum <1999J(P1)1709>. 

Organoytterbium chemistry has been developed in the last 20 years, although the development rate is much slower than the other lanthanides like samarium or cerium. Dianionic complexes that are produced from the reaction of ytterbium with diaryl ketones react with various kinds of electrophiles including carbon-heteroatom unsaturated bonds.35 Phenylytterbium iodide, a Grignard-type reagent, is known to have reactivity toward carbon dioxide,36 aldehydes, ketones,37,37 and carboxylic acid derivatives38,3811 to form the corresponding adducts respectively. 

A typical cyclization reaction starting from a 3-aminopyrazole is the transformation of 255 <2000BML821 >. This compound was treated first with ethoxycarbonyl isothiocyanate followed by sodium methoxide to yield a cyclic intermediate which was methylated by methyl iodide to give the stable product 256. In the cases of the synthesis of 257 <1995PHA675>, the dimeric 258 <2005JHC975>, the azo-substituted 259 <2001JCM439>, and the diaryl... 

The P—S bond formation of dialkyl (or diaryl) phosphites (21) with disulfide proceeds in an MeCN-NaBr/Et4NCl04-(Pt) system at 20 25 °C, giving phos-phorothiolates (22) in 72 91% yields (Scheme 9) [51]. In this reaction, both sodium iodide and sodium chloride are less effective than sodium bromide. Depending on the nature of the cation, the yields of (22) decrease in the order of Na+ (91%) > K+ (76%) > Li+ (69%) > Et4N+ (46%). 

The reaction of l,4-diaryl-2-methylthiopyrimidinium iodide (39) with hydrazine did not lead to the corresponding 2-hydrazino compound, as expected, but to the rearranged l-amino-2-arylaminopyrimidinium salt (40) (90JHC1441). This transformation also occurs via an Sn(ANRORC) process, involving the open-chain intermediate 41 (Scheme III.22). It cannot... 

Diaryl tellurides (generalprocedure). A mixture of powdered Te (0.128 g, 1.0 mmol), NaH (0.053 g, 2.2 mmol, 60% suspension in oil, washed with hexane) and dry DMF (3 mL) is heated at 140°C for 1 h. Within 0.5 h the initial deep red colour is lost, and a pale yellow snspension is obtained. After cooling at room temperature, the aryl iodide (2.0 mmol) in dry DMF (3 mL) is added and the mixture heated at 130°C for 24 h. After cooling at room temperatnre, the mixture is quenched with 10% aqueous NH4HSO4 (10 mL) and extracted with ether (10 mL). The ethereal extract is washed with HjO, dried (Na2S04) and evaporated, giving the teUuride, which is purified by column chromatography on SiOj (elnent/hexane). 

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. 

Chemical deoxygenation of sulfoxides to sulfides was carried out by refluxing in aqueous-alcoholic solutions with stannous chloride (yields 62-93%) [186 Procedure 36, p. 214), with titanium trichloride (yields 68-91%) [203], by treatment at room temperature with molybdenum trichloride (prepared by reduction of molybdenyl chloride M0OCI3 with zinc dust in tetrahydrofuran) (yields 78-91%) [216], by heating with vanadium dichloride in aqueous tetrahydrofuran at 100° (yields 74-88%) [216], and by refluxing in aqueous methanol with chromium dichloride (yield 24%) [190], A very impressive method is the conversion of dialkyl and diaryl sulfoxides to sulfides by treatment in acetone solutions for a few minutes with 2.4 equivalents of sodium iodide and 1.2-2.6 equivalents of trifluoroacetic anhydride (isolated yields 90-98%) [655]. 

Palladium(o) triphenylphosphine complexes catalyse the reduction of aryl bromides and iodides in a divided cell to give the diaryl [230]. The catalytic species... 

In a related three-component reaction procedure, aryl methyl ketones 724 have been combined with aryl aldehydes 725 and urea 726 at room temperature, using trimethylsilyl iodide as catalyst, to give 4,6-diaryl-3,4-dihydro-2(177)-pyrimidinones 727 <2005HCA2996>. A procedure using zinc iodide and microwave irradiation gave similar products <2007T1981>. 

The one-pot twofold Heck coupling of 2-pyridyldimethyl(vinyl)silane 42 was also carried out with two different aryl iodides to afford 2, 2 -diaryl(vinyl)silanes 43 in good yields (Scheme 15)." " A coordination of the pyridyl group to... 

An nice example of the formation of a five membered ring in crosscoupling reaction is the hexamethyldistannane mediated ring closure of the dihalogenated diaryl ether shown in 3.1. The first step of the process is the palladium catalyzed exchange of one of the iodides to a trimethylstannyl moiety, followed by the closure of the five membered ring in Stille coupling. 

Diaryl ethers, such as diphenyl ether, do not react with hydrogen iodide even at 200°.) There is no easy way to convert arenols to aryl halides, except where activation is provided by 2- or 4-nitro groups. Thus 2,4-dinitrobenzenol is converted to l-chloro-2,4-dinitrobenzene with phosphorus pentachloride ... 

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