in octane reflux (16 h); evapd. to dryness, dissolved in CH2Cl2, chromd. (alumina, hexane/dichloromethane), yellow, light gray and dark gray bands (benzenehexacarboxylate), evapd. to dryness; elem. anal.;
in hexane under N2; soln. with 5 equivalents acetylene was refluxed 12 h; filtration; washing (pentane); filtrate concentrated, cooled to -80°C; residue of pentane washing is washed (ether), addition of pentane, chromatography (Al2O3); residue (ether-insoluble) extracted (CH2Cl2), addition of ether; elem. anal;
