All chemicals were purchased from
commercial sources or provided by Pfizer and used without further
purification. Substrates2b –d were
synthesized according to the reported procedure. Unless stated otherwise,
all column purification were performed on a Biotage Selekt Flash Chromatography,
eluted with ethyl acetate: hexane, 0–15% gradient, detected
by UV absorption at 254 nm. Thin layer chromatography (TLC) was carried
out using Merck Millipore TLC silica gel 60 F254 glass plates. 1H, 13C, and 19F NMR spectra were measured
on a Bruker DPX-400 instrument (operating at 400 MHz for 1H, 100 MHz for 13C, and 375 MHz for 19F) or
a Bruker DPX-500 instrument (operating at 500 MHz for 1H and 125 MHz for 13C).
commercial sources or provided by Pfizer and used without further
purification. Substrates
synthesized according to the reported procedure. Unless stated otherwise,
all column purification were performed on a Biotage Selekt Flash Chromatography,
eluted with ethyl acetate: hexane, 0–15% gradient, detected
by UV absorption at 254 nm. Thin layer chromatography (TLC) was carried
out using Merck Millipore TLC silica gel 60 F254 glass plates. 1H, 13C, and 19F NMR spectra were measured
on a Bruker DPX-400 instrument (operating at 400 MHz for 1H, 100 MHz for 13C, and 375 MHz for 19F) or
a Bruker DPX-500 instrument (operating at 500 MHz for 1H and 125 MHz for 13C).