... Alternatively, treatment of 1b with EtMgBr followed by p-tosyl cyanide 16 afforded 1-cyanodipyrromethane 1b-N in 31% yield, together with an unidentified ... oil was chromatographed [silica, 7 × 26 cm, total 440 g, CH 2 Cl 2 to CH 2 Cl 2 /ethyl acetate (10:1), total volume ∼6 L ...