General Experimental Procedures. Optical rotations were
measured on an Autopol IV, model A21200 APIV/1W, digital
polarimeter (Rudolph Research Analytical). UV spectra were
measured on an Agilent 8453 UV−visible spectrophotometer from
190 to 400 nm using a 1 cm cell. FTIR spectra were measured on a
PerkinElmer Spectrum One instrument. Samples were deposited in
solution on NaCl disks and dried as films before measurement. NMR
spectra were recorded at 292 K on a Bruker Avance 400 spectrometer
(5 mm QNP with Z-gradient probe) operating at 400.13 MHz for 1
H
NMR or 100.61 MHz for 13C NMR. Each compound wa