... European Journal of Organic Chemistry. ... The combined organic extracts were dried (Na 2 SO 4 ), evaporated to dryness and purified by silica column chromatography (5a: hexane/ethyl acetate, 1:1; 5b: dichloromethane/ethyl acetate, 10:1 ... 5b M. Albrecht , I. Janser , J. Runsink , G ...