General Experimental Procedures. Optical rotations were
obtained using a Jasco P-1010 polarimeter. UV spectra were recorded
on an Amersham Biosciences Ultrospec 5300 Pro spectrophotometer,
and IR spectra were measured on a Bruker Alpha-P spectrometer. All
NMR experiments were carried out on a Varian INOVA 600 NMR
spectrometer. ESIMS spectra were obtained by LC/MS analysis, which
was performed on an Agilent 1200 Series HPLC/6130 Series mass
spectrometer. High-resolution mass spectra were obtained on a Waters
Micromass Q-Tof Ultima ESI-TOF mass spectrometer. All the
compounds were purified on an Agilent 1100 series HPLC (Agilent
Technologies) using a Phenomenex Luna phenyl-hexyl column (25
cm × 10 mm, 5 μm particle size), a Phenomenex Luna phenyl-hexyl
column (250 × 21.2 mm, 10 μm particle size), and a Phenomenex
Luna C18 HPLC column (250 × 21.2 mm, 5 μm particle size)