General Experimental Procedures. Optical rotations were
measured on a Rudolph Autopol IV polarimeter at a wavelength of
50 nm. ECD spectra were recorded at 25 °C on a Jasco-715
spectrophotometer. IR spectra were recorded on a Perkin-Elmer 1600
FT IR spectrophotometer as KBr pellets, and the absorption
frequencies are expressed in reciprocal centimeters (cm−1
). Electronic
absorption spectra were recorded using a Jasco V-630 spectrophotometer.
Emission spectra were measured on a Jasco FP 6600
spectrofluorometer. Mass spectral studies were carried out on a
Hewlett-Packard 5989B MS. 1D and 2D NMR experiments were
performed on a Bruker Avance III spectrometer at 400 MHz.