Diarylalkane

Haloalkylations are accompanied by further alkylation by the initially formed haloalkylated product, yielding diarylalkanes or cychalkylated products, eg, ben2ene reacts with CCl in the presence of AlCl to give C H CCl and (43). With dichloromethane, the initially formed ben2yl chloride is... 

The solvent should have high solvability with no or very low odor. Two examples are SAS-296 (diarylalkane, Nippon Petroleum Chemicals) and KMC-113 (dialkylnaphthalene, Kureha Chemicals). Latex is used as binder. Wheat starch functions as a stilt preventing the rupture of microcapsules... 

The relationship between added methylene groups and potency depends to some extent on the compound being tested. In a 2000 study on a family of compounds known as the N,N -diarylalkane-diamides, a team of Czech and Slovak researchers found that increasing the number of methylene groups in a compound from two to seven resulted in a nearly linear increase in the potency of the analog produced. Researchers explained their results by pointing out that methylene groups are nonpolar and tend to increase the tendency of a compound to dissolve in fatty substances, such as those... 

Oxidation of the series of a,co-diarylalkanes 27 gives both the cyclised product 28 and a dehydrodimer type product 29 depending on the length of the alkane... 

Racemic, cyclic and open-chain 1,2-diarylalkanes have been deprotonated under the regime of the sparteine protocoP . )V-Methyl-4-phenyl-l,2,3,4-tetrahydroisoquinoline (276) was deprotonated by i-BuLi/(—)-sparteine (11) and the intermediates 277 were quenched by MeOD. When performing the reaction in diethyl ether, (R)-278 was isolated with high ee values, up to 88% (equation 68). ... 

Diarylalkanes are important structural motifs that can be found in a variety of pharmaceuticals, agrochemicals and fine chemicals. Examples are papaverin, avrainvilleol and beclobrate (Scheme 2). Traditionally, 1,1-diarylalkanes can be prepared from benzyl halides and the corresponding arenes under Friedel-Crafts-type conditions. 

Scheme 2 Diarylalkanes as desirable structural motif in many biologically active compounds and pharmaceuticals...

When optically pure (S)- 1-phenylethanol Id was treated with p-xylene only racemic 1,1-diarylalkane 4a was isolated (Scheme 6). This strongly implies a carbocation as the reactive intermediate in the Bi(OTf)3-catalyzed Friedel-Crafts alkylations. Mechanistically, it is not clear whether Bi(III), in situ generated TfOH, or both Lewis and Brpnsted acids together are involved in the catalytic cycle... 

This methodology has also been extended to the alkylation of p-hydroxyester 6 in order to obtain the p-carboxy-substituted diarylalkane 7 (Scheme 9a). The... 

Besides the high efficiency of this route, many styrenes are readily available. This widens the product scope for 1,1-diarylalkanes and would additionally complement the previously described benzyl-alcohol-based Friedel-Crafts-type alkylations. 

Similar to Rueping s procedure, Hua and coworkers developed a BiCl3-catalyzed synthesis of 1,1-diarylalkanes also starting from electron-rich arenes and styrenes [68]. They found that styrenes 37 could be transformed to the substituted cyclopentanes 39 if catalytic amounts BiCl3 were applied (Scheme 30). This reaction is believed to proceed via an intermolecular ene-reaction between styrene and the carbocationic intermediate I, followed by an intramolecular Friedel-Crafts alkylation of the resulting intermediate II. 

This then readily undergoes cleavage to produce benzene and a dialkylbenzene. The initial R+ cation initiating the reaction might arise from some impurity present in the reaction mixture. Consistent with this mechanism is the observed very low reactivity of methylbenzenes due to the necessary involvement of the primary benzyl cations. At the same time 1,1-diarylalkanes undergo cleavage with great ease. 

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