Optical
rotations were measured using a JASCO P-2000 polarimeter with a 10
cm cell. UV spectra were obtained using Varian Cary 50 Bio UV–visible
spectrophotometer. IR spectra were acquired on a PerkinElmer 1600
series FTIR spectrometer. 1H, 13C, and 2D NMR
spectral data were obtained on a Varian Inova 500 MHz NMR spectrometer.
High-resolution mass spectra were recorded on a ThermoFinnigan MAT900XL
instrument with an Agilent ESI-TOF detector at The Scripps Research
Institute, La Jolla, CA. Low-resolution LC/MS spectra were obtained
on a Hewlett-Packard HP1100 integrated LC-MS system with a reversed-phase
C18 column (Agilent, 4.6 mm × 100 mm, 5 μm) at a flow rate
of 0.7 mL/min. Reversed-phase HPLC separations were performed using
a semipreparative C18 Phenomenex Luna (2) 5 μm (10 mm ×
250 mm) column with a CH3CN/H2O gradient solvent
system. Preparative HPLC was performed using a Waters model 4000 system
with a UV variable-wavelength detector monitoring at 210 nm using
a C18 Nova-Pak 6 μm 60 Å, (40 mm × 300 mm) column.
rotations were measured using a JASCO P-2000 polarimeter with a 10
cm cell. UV spectra were obtained using Varian Cary 50 Bio UV–visible
spectrophotometer. IR spectra were acquired on a PerkinElmer 1600
series FTIR spectrometer. 1H, 13C, and 2D NMR
spectral data were obtained on a Varian Inova 500 MHz NMR spectrometer.
High-resolution mass spectra were recorded on a ThermoFinnigan MAT900XL
instrument with an Agilent ESI-TOF detector at The Scripps Research
Institute, La Jolla, CA. Low-resolution LC/MS spectra were obtained
on a Hewlett-Packard HP1100 integrated LC-MS system with a reversed-phase
C18 column (Agilent, 4.6 mm × 100 mm, 5 μm) at a flow rate
of 0.7 mL/min. Reversed-phase HPLC separations were performed using
a semipreparative C18 Phenomenex Luna (2) 5 μm (10 mm ×
250 mm) column with a CH3CN/H2O gradient solvent
system. Preparative HPLC was performed using a Waters model 4000 system
with a UV variable-wavelength detector monitoring at 210 nm using
a C18 Nova-Pak 6 μm 60 Å, (40 mm × 300 mm) column.