General Experimental Procedures. Melting points were
measured on a Buchi-540 melting point apparatus and are
uncorrected. Optical rotations were measured with a Jasco
P-1020 polarimeter. IR spectra were obtained on a PerkinElmer
BX FT-IR spectrometer. NMR spectra were run on a
Bruker DRX-500 spectrometer. EIMS were recorded on a
Hewlett-Packard 5989 B instrument and FABMS on a JEOL
SX 102/DA-6000 mass spectrometer. Medium-pressure liquid
chromatography (MPLC) was carried out on a Buchi 687
Gradient Former with a Buchi 688 chromatographic pump.
MCI gel [CHP 20, 75-150 µm] was used for reversed-phase
columns, and silica gel 60 (Merck, 100-200 mesh) was used
for final purifications.