... 319/86 Bishyrocotarnines - Stereochemical Aspects ... benzene for 48 h. After evaporation and drying (see lOa) 10b was purified by cc on silica (chloroform/ether 3:l-vol): 504 mg (66 %) yellow oil, which was boiled with a little ether: 340 mg (44 %) colourless crystals, mp. ... 12 Org. ...