General Experimental Procedures. A SANYO Gallenkamp
(UK) melting point apparatus was used to determine melting points. A
JASCO DIP-1000 digital polarimeter was used to identify the optical
rotation. An Agilent 8453 UV−visible spectrophotometer (Germany)
was used to record the UV spectra. IR spectra were recorded as thin
films using a PerkinElmer Spectrum One FT-IR spectrophotometer
(UK). The NMR spectra were recorded on a Varian Mercury plus
spectrometer (UK) operating at 400 MHz (1
H) and at 100 MHz
(13C). The solvent residual peak was used for chemical shift
referencing (δH 3.31, δC 49.0 for methanol-d4 and δH 7.26, δC 77.2
for CDCl3). Mass spectra were obtained on a Micromass Q-TOF 2
hybrid quadrupole time-of-flight (Q-TOF) mass spectrometer with a
Z-spray ES source (Micromass, UK). Column chromatography (CC)
was carried out using silica gel 60 (100−200 mesh, Merck). TLC was
performed on silica gel 60 F254 (Merck) precoated aluminum sheets.
The compounds were visualized under UV light and by spraying with
acidic anisaldehyde solution followed by heating. Gel filtration was
carried out over Sephadex LH-20 (Pharmacia) suspended in MeOH.
Distilled solvents were used throughout the separation process.