Plates
were visualized by spraying with Dragendorff’s reagent or with
50% H2SO4 and then heating on a hot plate. HPLC was
performed on a JASCO PU-980 apparatus equipped with a UV-
970 detector. Develosil ODS-5 (250 _ 4 mm i.d.) and preparative
ODS-5 (250 _ 20 mm i.d.) columns were used for
analytical and preparative purposes, respectively.