Versatile Synthesis of Unsymmetrically Substituted Triphenylenes
作者:Neville Boden、Richard J. Bushby、Andrew N. Cammidge、Gareth Headdock
DOI:10.1055/s-1995-3853
日期:1995.1
Oxidative coupling of 3,3’,4,4’-tetrahexyloxybiphenyl and a benzene derivative using iron(III) chloride, followed by a reductive workup with methanol, provides an easy, versatile synthesis of unsymmetrically substituted triphenylenes. These molecules are essential requisites for the production of new discotic liquid crystals and include systems with α-substituents and other substitution patterns previously impossible to obtain.
A 3-fold stereoselective cyclocondensation of the azomethines 3 and 11 yields the [18]annulenes 4 and 12, respectively. The [abc]-annelation of naphthalene or phenanthrene systems realized here for the first time, leads to nonplanar molecules consisting of 'aromatic islands", which are connected by (E)-configured olefinic bridges. The absence of a diamagnetic ring current rules out a macrocyclic aromaticity. The NMR investigation, based on selective deuterations, is sustained by force field calculations (MMX). The disc-like compounds represent discotic mesogens of an enormous diameter. The formation of thermotropic liquid crystals can be achieved by the introduction of long flexible alkoxy chains.
SYNTHESIS OF SUBSTITUTED TRIPHENYLENES, USEFUL AS DISCOTIC LIQUID CRYSTALS
申请人:BRITISH TECHNOLOGY GROUP LTD
公开号:EP0703885A1
公开(公告)日:1996-04-03
[EN] SYNTHESIS OF SUBSTITUTED TRIPHENYLENES, USEFUL AS DISCOTIC LIQUID CRYSTALS<br/>[FR] SYNTHESE DE TRIPHENILENES SUBSTITUES UTILES POUR LES CRISTAUX LIQUIDES EN FORME DE DISQUE
申请人:BRITISH TECHNOLOGY GROUP LIMITED
公开号:WO1994029243A1
公开(公告)日:1994-12-22
(EN) Unsymmetrically substituted triphenylenes required in the synthesis of polymeric discotic liquid crystals are made using iron (III) chloride in organic solvent at room temperature to effect the oxidative coupling of 1,2-dialkoxybenzenes to 3,3',4,4'-tetraalkoxybiphenyls. This is followed by a reductive workup. The same oxidation-reduction protocol also proves effective in the trimerisation of 1,2-dialkoxybenzenes.(FR) Les triphénylènes à substitution asymétrique nécessaires à la synthèse des cristaux liquides (en disque) sont obtenus en utilisant du chlorure de fer (III), contenu dans un solvant organique à température ambiante, pour réaliser la liaison oxydante de 1,2-dialkoxybenzènes et de 3,3',4,4'-tétra-alkoxybiphényles. Ceci est suivi d'un bilan réducteur. Le même protocole d'oxydo-réduction a prouvé son efficacité dans la trimérisation des 1,2-dialkoxybenzènes.
C2‐Symmetric hexahelicenes 3a–3g, which bear four or six alkoxy chains, were prepared in eight‐to‐nine reaction steps in high overall yields. The final step consisted of a twofold oxidative photocyclization of the corresponding 2,7‐bis(2‐phenylethenyl)naphthalenes. Long (and branched) chains provide a good solubility and processability, which is a prerequisite for applications in organic synthesis