All reactions were performed in glass flasks under
N2. Starting reagents were purchased from commercial suppliers
and
used without further purification, unless otherwise specified. Chromatographic
elution was conducted under continuous monitoring by thin-layer chromatography
using silica gel 60F254 (Merck & Co., Inc.) as the stationary
phase and the elution solvent used in column chromatography as the
mobile phase. A UV detector was used for detection. Silica gel SK-85
(230–400 mesh) or silica gel SK-34 (70–230 mesh), both
of which were manufactured by Merck & Co., Inc., was used as the
column-packing silica gel. 1H and 13C NMR spectra
were obtained on Varian Unity 400 MHz or JEOL JNM-GSX400 MHz spectrometers.
Spectra were recorded in the indicated solvent at ambient temperature,
and chemical shifts were reported in ppm (δ) relative to the
solvent peak. Resonance patterns are represented by the following
notations: br (broad signal), s (singlet), d (doublet), t (triplet),
q (quartet), and m (multiplet). HRMS was conducted using an LC–MS
system consisting of a Waters Xevo Quadropole-ToF MS and an Acquity
UHPLC system.
N2. Starting reagents were purchased from commercial suppliers
and
used without further purification, unless otherwise specified. Chromatographic
elution was conducted under continuous monitoring by thin-layer chromatography
using silica gel 60F254 (Merck & Co., Inc.) as the stationary
phase and the elution solvent used in column chromatography as the
mobile phase. A UV detector was used for detection. Silica gel SK-85
(230–400 mesh) or silica gel SK-34 (70–230 mesh), both
of which were manufactured by Merck & Co., Inc., was used as the
column-packing silica gel. 1H and 13C NMR spectra
were obtained on Varian Unity 400 MHz or JEOL JNM-GSX400 MHz spectrometers.
Spectra were recorded in the indicated solvent at ambient temperature,
and chemical shifts were reported in ppm (δ) relative to the
solvent peak. Resonance patterns are represented by the following
notations: br (broad signal), s (singlet), d (doublet), t (triplet),
q (quartet), and m (multiplet). HRMS was conducted using an LC–MS
system consisting of a Waters Xevo Quadropole-ToF MS and an Acquity
UHPLC system.