having a direct inlet system.
HRFABMS were measured on a JEOL JMS-HX 110 mass
spectrometer. Si gel 60 (Macherey-Nagel, 230-400 mesh) was
used for column chromatography, precoated Si gel plates
(Macherey-Nagel, SIL G25 UV254, 0.25 mm) were used for
analytical TLC, and precoated Si gel plates (Macherey-Nagel,
SIL G/UV254, 0.25 mm) were used for preparative TLC. 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.