Melting
points were determined using a MEL-TEMP II capillary melting
point apparatus and are uncorrected. Nuclear magnetic resonance (1H NMR and 13C NMR) spectra were obtained on a Varian
Avance DPX-500 MHz NMR spectrometer or a Bruker Unity Inova 300 MHz
NMR spectrometer. Chemical shifts are reported in parts per million
(ppm) with reference to internal solvent. Mass spectra (MS) were conducted
on a PerkinElmer Sciex AP1 150 EX mass spectrometer equipped with
ESI (turbospray) source. Elemental analyses were performed by Atlantic
Microlab Inc., Atlanta, GA. The purity of the compounds (>95%)
was
established by elemental analysis. Optical rotations were measured
on an AutoPol III polarimeter, purchased from Rudolf Research. Analytical
thin-layer chromatography (TLC) was carried out using EMD silica gel
60 F254 TLC plates. TLC visualization was achieved with
a UV lamp or in an iodine chamber. Flash column chromatography was
done on a CombiFlash Companion system using ISCO prepacked silica
gel columns or using EM Science silica gel 60A (230–400 mesh).
Solvent system: CMA80 80:18:2 CHCl3:MeOH:concd NH4OH. Unless otherwise stated, reagent-grade chemicals were obtained
from commercial sources and were used without further purification.
All moisture- and air-sensitive reactions and reagent transfers were
carried out under dry nitrogen.
points were determined using a MEL-TEMP II capillary melting
point apparatus and are uncorrected. Nuclear magnetic resonance (1H NMR and 13C NMR) spectra were obtained on a Varian
Avance DPX-500 MHz NMR spectrometer or a Bruker Unity Inova 300 MHz
NMR spectrometer. Chemical shifts are reported in parts per million
(ppm) with reference to internal solvent. Mass spectra (MS) were conducted
on a PerkinElmer Sciex AP1 150 EX mass spectrometer equipped with
ESI (turbospray) source. Elemental analyses were performed by Atlantic
Microlab Inc., Atlanta, GA. The purity of the compounds (>95%)
was
established by elemental analysis. Optical rotations were measured
on an AutoPol III polarimeter, purchased from Rudolf Research. Analytical
thin-layer chromatography (TLC) was carried out using EMD silica gel
60 F254 TLC plates. TLC visualization was achieved with
a UV lamp or in an iodine chamber. Flash column chromatography was
done on a CombiFlash Companion system using ISCO prepacked silica
gel columns or using EM Science silica gel 60A (230–400 mesh).
Solvent system: CMA80 80:18:2 CHCl3:MeOH:concd NH4OH. Unless otherwise stated, reagent-grade chemicals were obtained
from commercial sources and were used without further purification.
All moisture- and air-sensitive reactions and reagent transfers were
carried out under dry nitrogen.