CuI/HMPA-Catalyzed Alkylation to Tolan: A Valuable Method for Discotic Liquid Crystal Hexabenzocoronene
In this paper, a novel protocol of akylation to tolan using CuI/HMPA as catalyst for synthesizing alkyl-substituted hexabenzocoronene (HBC) was described. The key step in the route was the construction of tolan bearing 2 long side chains, which was completed in the first step via coupling reaction between 4, 4’-Bis (bromomethyl) tolan (1) and Grignard Reagent in a mild condition. Afterward, Co2(CO)8 catalyzed cyclotrimerization gave hexaphenylbenzene derivative (HPB) which could be easily separated by column chromatography and recrystalization. The planarization of HPB was carried out with FeCl3 /MeNO2 to afford the desired HBC with long odd-carbon alkyl chains in good overall yields.
Yuan Ming Huang
Y. Jiang et al., "CuI/HMPA-Catalyzed Alkylation to Tolan: A Valuable Method for Discotic Liquid Crystal Hexabenzocoronene", Solid State Phenomena, Vols. 181-182, pp. 173-176, 2012