Page 1. Monatshefte füur Chemie 134, 37–43 (2003) DOI 10.1007/s00706 ... The crude products (3a and 3b) were purified by crystallization from isohexane or by chromatography (3c, 3d, 5b, 5c, 5d, 7, 8, 10, and 12) on silica using isohexane=ethyl acetate (9=1) as the eluent. ...