From diarylmethanes

Initially, this field was pioneered by Li who reported in 2007 on the formation of new carbon-carbon bonds directly starting from diarylmethanes and 1,3-dicarbonyl compounds under mild reaction conditions (80-100 °C, 5-36 h) in the presence of catalytic quantities of an inexpensive iron precursor (iron(ii) chloride, 20 mol%) and stoichiometric quantities of an oxidant (DTBP). The overall reaction can be regarded as an iron(ii) chloride-catalysed oxidative activation of a benzylic carbon-hydrogen bond followed by a cross-coupling reaction to form a carbon-carbon bond (Scheme 13.7, bottom). The mechanistic proposal is based on a single-electron transfer pathway as shown in Scheme 13.7. Initial homolysis of DTBP in the presence of the iron(ii) salt forms both tert-butoxyl radical and an iron(iii) species. Then, proton abstraction from the diarenemethane generates the two key... 

Anthracenes from ort/io-acyl diarylmethanes via acid-catalyzed cyclodehydration. 

Final confirmation of our interpretation of the rate of oxygen absorption by diphenylmethane was provided by studying the loss of deuterium from the deuterated sample of diphenylmethane. After 1.50 and 2.70 minutes in a solution containing 0.233M potassium ferf-butoxide and 0.10M diarylmethane, and in the absence of oxygen, the recovered diphenylmethane was found to contain dideuterio, monodeuterio, and undeuterated diphenylmethane in the ratios, 74.0 23.8 2.2 (1.5 minutes)... 

Reduction of diaryl thioketones with ytterbium metal affords a mixture of the corresponding thiols and diarylmethanes together with products arising from homocoupling reactions (equation 119)433. 

Another example is the photoreaction of tctrazolo[ 1,5- ]pyrimidinc 14 with aromatic compounds in the presence of trifluoroacetic acid (TFA) to give 2-(2-, 3-, and 4-substituted anilino)pyrimidines together with 2-aminopyridine and biphenyl or diarylmethanes. Here the key intermediate is also the 2-pyrimidylnitrenium ion originating from the photochemical decomposition of an imidoyl azide. This ion, depending on the reaction conditions, is present either in the singlet or triplet state and this governs the composition of the products (Scheme 11) <1998JP0478>. 

Substituted diarylmethanes have been prepared from formaldehyde and a variety of its derivatives. Sulfuric acid is a common catalyst. The procedure described is based on the general method of Gordon, May, and Lee. Formic acid is preferable to sulfuric acid as a catalyst because it is capable of acting as a solvent as well, thus eliminating troublesome emulsions. Side reactions such as sulfonation are avoided. 

In 1884, Friedel and Crafts reported that the alkylation of benzene or toluene with dichloromethane in the presence of AlCb avoided the corresponding diarylmethanes, besides other products derived from further alkylation and other transformations. pr ucts from the reaction with benzene are shown... 

Biaryls and diarylmethanes. These compounds can be prepared from coupling reactions of aryl iodides with organozinc reagents. Notably biphenylnonaflates are obtained from iodophenyl nonaflates at room temperature and they undergo further coupling at 55-60°. 

On the other hand, Emilies 2, 5 and 8 were formed from bimolecular reactions involvii benzilic-type carbocations and diarylmethane intermediates [3,8],... 

Reactions of type A (Figure 10.14) involve a carbanion, originating from an ionized phenol structure in lignin, and a quinone methide. The anion can be located either in the aromatic ring or, in some cases, in the side chain of a conjugated aromatic system. Normally, the resulting product will be a substituted diarylmethane structure, but... 

Alkylbenzenes are prepared by the Friedel-Crafts reaction in which benzene is reacted with an alkyl halide in the presence of a Lewis acid such as AlCl. Diarylmethanes are formed in this manner from dichloromethane and triarylmethanes from trichloromethane. 

Interestingly, subsequent work from Lu s group showed that tuning the concentration of TFA would allow the regioselective homocoupling of p-xylene to generate a biaryl or diarylmethane in the presence of the Pd(OAc)2/TFA/K2S20g... 

The intermolecular Friedel-Crafts alkylation with benzyUc and aUyUc halides occurs at room temperature in CH2CI2. Diarylmethanes are also obtained in moderate yields from arenes and benzyl alcohols on heating the mixtures with InCls 4H2O and acetylacetone at 120°. l-VinyltetraUn and 4-vinyltetrahydrDisoquinoline derivatives are readily formed by an intramolecular aUylation. ... 

Diarylmethanes from ethers Replacement of alkoxyl by hydrogen... 

Numerous applications of the NaBHVTFA deoxygenation of diarylmethanols and related benzylic alcohols have been reported, especially those involving diarylmethanols. In addition to the examples shown earlier,2 diarylmethanes 57-64 have been prepared from the corresponding alcohols with NaBHVTFA. The site of reduction is shown as a bold H. 

Such reactions, which will not be discussed further here, include the formation of diarylmethanes from an aldehyde and two molecules of an aromatic hydrocarbon, of triphenylmethane derivatives from an aldehyde and two molecules of an aromatic amine, and of phthaleins from phthalic anhydride and two molecules of phenol or resorcinol. 

Diarylmethanes. With (Ph3P>4Pd as catalyst, unsymmetrical ArCH2Ar are obtained from a cross-coupling reaction between aryl triflates and Bu4N[Bn,SnF2] in DMF. 

Another improvement of the DPM rigidity and preorganization without alteration of the substitution pattern is the back-stabilization of the gable conformation. The 1.1-diphenylcyclopropane derivatives invariably show preference for the gable conformation, as revealed from x-ray data. Also, in diarylmethane-bridged fullerenes, the gable disposition was described as the most stable conformation. However, no experimental rotational barriers were reported until now. 

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