Oligophenylenes, synthesis

Wu J, Watson MD, Tchebotareva N, Wang Z, Miillen K (2004) Oligomers of hexa-pcn-hexabenzocoronenes as super-oligophenylenes synthesis, electronic properties, and self-assembly. J Org Chem 69 8194-8204... 

Rehahn et al. [35] recently presented the synthesis of constitutionally homogeneous oligophenylenes, 22a/b, with 2,5-alkyl substituents located on the central aromatic ring, generated via the cross-coupling reaction of Suzuki. They are exclusively linked in the para-positions and composed of 3 -15 benzene rings. 

This modular methology involves the repetition of directed protection/cyclo-addition/deprotection steps, and allows for the synthesis of monodisperse dendritic oligophenylenes of the first (46a, 22 benzene rings) and second (46b, 62 benzene rings) generation [60]. Within the synthetic sequence, the authors made use of the different reactivities of protected and deprotected ethynylene functions within the key cycloadditon step. 

Keywords Dendrimers, linear aliphatic molecules, oligophenylenes, repetitive synthesis, supramolecular chemistry. 

The decrease in thickness of the monolayer upon chemical flattening of the molecules can be shown by STM. The importance of the defined graphitic structures suggests the transfer of this novel strategy, namely the surface-induced PAH synthesis, to considerably larger oligophenylene precursors. 

Rhodium-catalyzed alkyne cyclotrimerization is also applicable to the synthesis of a polyalkyne substrate bearing ether-linked 1,6-diyne moieties 59, which is easily prepared by Pd-Cu-catalyzed Sonogashira couphng reactions. These reactions provide a novel and efficient synthetic route to oligophenylene 60, which bears benzodihydrofur-an moieties (Scheme 7.17) [40]. 

D.M., Beck, P.A. and Strongin, R.M. (2000) Convenient iterative synthesis of an octameric tetracarboxylate-functionalized oligophenylene rod with divergent end groups. Organic Letters, 2, 3201 1. 

Deng, X., Mayeux, A. and Cai, C. (2002) An efficient convergent synthesis of novel anisotropic adsorbates based on nanometer-sized and tripod-shaped oligophenylenes end-capped with triallylsilyl groups. The Journal of Organic Chemistry, 67, 5279-83. 

M. D (2004) Synthesis and functional properties of strongly luminescent diphenylamino end-capped oligophenylenes. The Journal of Organic Chemistry, 69, 921-7. 

More recently, homologues of triphenylene with various size and perimeter types could be made by mild intramolecular dehydrogenation of suitable oligophenylene precursors. Thus, the transformation of hexaphenylbenzene 169 into hexabenzocoronene 170 occurs in quantitative fashion (see scheme 41) and non-hexagonal disc-type structures, such as C , C72 and ,2 are also available (see chart 27) [228]. The success of the unconventional synthesis and the loss of a large number of hydrogens can be monitored by LD-TOF mass spectrometry. 

Ohkita M, Ando K, Yamamoto K-i, Suzuki T, Tsuji T (2000) First Dewar benzene approach to acetylenic oligophenylene macrocycles synthesis and structure of a molecular rectangle bearing two spindles. Chem Commun (l) 83-84... 

The synthesis of a series of poly[(disilanylene)-oligophenylenes] (34, m — A) have been reported [53] and their conducting properties have been examined. Poly[(disilanylene)biphenyIenes] (34, m = 2) are synthesized by the sodium condensation of the respective bis(chlorosilyl)biphenyls, similar to the method for the synthesis of polymers 30-32, as shown in Scheme 15.3. Poly[(disilanylene)terphenylenes and quaterphenylenes] (34, m = 3 and 4) are prepared by the reaction of 1,4-dibromobenzene and 4,4 -dibromo-biphenyl with di-Grignard reagents prepared from bis(bromophenyl)disilanes in the presence of a catalytic amount of dichloro(diphenylphosphinoethane)nickel-(II) in THE at 150°C (Scheme 15.3) [51]. 

Synthesis of C96-C12 precursor 1,3,5-tris[3, 4 -di(4"-dodecylphenyl)-2, 5 -diphenyiphenyijbenzene (44a) by Diels-Alder cycloaddition reaction - a representative procedure for the synthesis of branched oligophenylenes [50]... 

Scheme 6.5. Synthesis of oligophenylene macrocycles 31 and 32. Reagents and conditions (a) 1 M HCI, THF (b) i-PraSiOTf, EtjN (c) hv, CH2CI2. 12 °C.

The synthetic utility of the Suzuki reaction for polymer synthesis has also been demonstrated through the synthesis of polymers with Frechet-type dendritic substituent groups (247) and through progress made toward the preparation of large oligophenylene cycles (248),... 

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