反応手順
To a degassed solution of 940 mg of 4,4′-dichlorobenzil (3.37 mmol) and 1.22 g of 1,3-di(biphenyl-3-yl)propan-2-one (7, 3.37 mmol) in 20 ml of tert-butanol was added, at 80° C., a methanolic tetrabutylammonium hydroxide solution (1M, 1.7 ml, 1.7 mmol). The reaction solution was stirred at 80° C. for 20 minutes, and the reaction then stopped by adding water. The mixture was extracted three times with dichloromethane and the collected organic phases were washed with saturated sodium chloride solution and dried over magnesium sulfate, before the solvent was distilled off under reduced pressure. The crude product was purified by column chromatography (silica gel, eluent: hexane with 20% DCM) and gave 1.56 g of the tetraarylcyclopentadienone 8b as a pale violet solid (77%, 2.58 mmol). Elemental analysis measured: C 81.3; H 3.3% (calculated for C41H26Cl2O: C, 81.3; H, 4.3%); 1H NMR (700 MHz, d8-THF) δ=7.52 (s, 2H, CH), 7.50 (d, J=7.8 Hz, 2H, CH), 7.42 (d, J=7.2 Hz, 4H, CH), 7.36 (t, J=7.7 Hz, 4H, CH), 7.32 (m, 6H, CH), 7.27 (t, J=7.3 Hz, 2H, CH), 7.23 (d, J=7.8 Hz, 2H, CH), 7.06 (d, J=8.5 Hz, 4H, CH); 13C NMR (175 MHz, d8-THF) δ=199.86, 154.28, 141.91, 141.82, 135.61, 133.14, 132.14, 132.10, 129.98, 129.90, 129.70, 129.69, 129.52, 128.27, 127.78, 127.20, 126.73; MS (MALDI-TOF): m/z (%): 604.6 (100) [M+] (calculated for C41H26Cl2: 604.1); Rf (hexane with 10% ethyl acetate)=0.47.
