NMR Experiments. All NMR spectra were acquired at 30 °C
in methanol-d4. 1D 1H NMR spectra with 32k data points, sweep
width of 8.5 ppm, and pulse repetition time of 4.3 s were recorded
using 8-2048 transients depending on sample concentration and
without solvent peak suppression. Magnitude-mode, gradientselected
COSY experiments were performed collecting 1604
512 data points with 4-64 transients, applying sine-bell apodization
in both directions prior to Fourier transformation. Phase-sensitive
TOCSY spectra (80-ms spin lock) were recorded with 1024 512
data points (4 transients), and the data were Fourier-transformed
using a ð/2-shifted sine-bell in both dimensions. HSQC spectra
were acquired using gradient selection and adiabatic pulses,42
collecting 1276 512 data points (8-128 transients/increment),
and the data were Fourier-transformed using ð/2-shifted squared
sine-bell in both dimensions. HMBC data (acquired using gradient
selection and adiabatic pulses42) contained 1024 512 data points
(24 transients/increment) and were Fourier-transformed using a
nonshifted sine-bell in both dimensions. The heteronuclear correlations
were optimized for 1JC,H ) 140 Hz and nJC,H ) 8 Hz.
Spectral widths were adjusted to the individual samples, and linear
prediction was applied in all 2D experiments to improve resolution
in the indirect direction. 1H and 13C chemical shifts were
referenced to solvent signals of methanol-d4, ä(1H) ) 3.31 and
ä(13C) ) 49.1.
NMR Experiments. All NMR spectra were acquired at 30 °C
in methanol-d4. 1D 1H NMR spectra with 32k data points, sweep
width of 8.5 ppm, and pulse repetition time of 4.3 s were recorded
using 8-2048 transients depending on sample concentration and
without solvent peak suppression. Magnitude-mode, gradientselected
COSY experiments were performed collecting 1604
512 data points with 4-64 transients, applying sine-bell apodization
in both directions prior to Fourier transformation. Phase-sensitive
TOCSY spectra (80-ms spin lock) were recorded with 1024 512
data points (4 transients), and the data were Fourier-transformed
using a ð/2-shifted sine-bell in both dimensions. HSQC spectra
were acquired using gradient selection and adiabatic pulses,42
collecting 1276 512 data points (8-128 transients/increment),
and the data were Fourier-transformed using ð/2-shifted squared
sine-bell in both dimensions. HMBC data (acquired using gradient
selection and adiabatic pulses42) contained 1024 512 data points
(24 transients/increment) and were Fourier-transformed using a
nonshifted sine-bell in both dimensions. The heteronuclear correlations
were optimized for 1JC,H ) 140 Hz and nJC,H ) 8 Hz.
Spectral widths were adjusted to the individual samples, and linear
prediction was applied in all 2D experiments to improve resolution
in the indirect direction. 1H and 13C chemical shifts were
referenced to solvent signals of methanol-d4, ä(1H) ) 3.31 and
ä(13C) ) 49.1.
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