Chemical silica gel 60n

Analytical TLC was performed on Kieselgel F₂₅₄ plates (Merck, Darmstadt, Germany) and visualized by UV light (254 nm, Axel, Osaka, Japan). Column chromatography was performed using Chemical silica gel 60N (neutral, KANTO Chemical, Tokyo, Japan). Physical data were obtained as follows. NMR spectra were recorded on a Bruker FT-NMR AV400 or AV500 instrument (Billerica, MA, USA). ¹H NMR spectra were recorded at 400 or 500 MHz, referenced to TMS in CDCl₃ (0.00 ppm), DMSO-d₆ (2.50 ppm). ¹³C NMR spectra were recorded at 100 or 125 MHz, referenced to TMS in CDCl₃ (0.00 ppm). ³¹P NMR spectrum was recorded at 162 or 202 MHz, referenced to phosphoric acid as an external reference in CDCl₃ (0.00 ppm). Chemical shifts are reported in parts per million (δ), and signals are expressed as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), or br (broad). All exchangeable protons were detected by addition of D₂O. Mass spectra were recorded on a quadrupole SQD2 spectrometer (Waters, Milford, MA, USA) for LRMS or a TOF SYNAPT G2-Si HDMS spectrometer (Waters) for HRMS. All the chemical reagents and solvents used were commercially available and used without further purification.

All the reagents were obtained from commercial sources and used without further purification. The solvents were not anhydrous-grade. Flash chromatography was performed using Kanto Chemical silica gel 60N (spherical, neutral). JEOL JNM-ECX400P (JEOL, Japan) was used to record ¹H NMR and ¹³C NMR spectra. Chemical shifts for ¹H NMR spectra were reported as δ in parts per million (ppm) downfield from SiMe₄ (δ 0.0) and relative to the signal of CDCl₃ (δ 7.26, singlet), while ¹³C NMR spectra were reported as δ in ppm downfield from SiMe₄ (δ 0.0) and relative to the signal of CDCl₃ (δ 77.16, triplet). HPLC and MS spectra were recorded on a Shimadzu LC20A system (Shimadzu Corporation, Japan) and LCMS-2010EV or a Shimadzu LC20A XR system and amaZon SL, using a C18 column (YMC-Pack Pro C18, 5 µm, 250 mm × 4.6 mm ID; MonoBis low-pressure type, 11 nm, 150 mm × 3.2 mm ID; Kinetex 5 µm EVO C18 100 Å LC Column, 250 mm × 4.6 mm ID; or Kinetex 1.7 µm EVO C18 100 Å LC Column, 100 mm × 2.1 mm ID) with detection at 215 nm. Chemiluminescent nitrogen detector (CLND) spectra were recorded on a Shimadzu LC10A system and Antek 8060 (PAC, Houston, TX, USA). High-resolution mass spectra (HRMS) were recorded on Bruker ultrafleXtreme (Bruker, Billerica, MA, USA). (Copies of the ¹H-NMR and HPLC charts and experimental data for compounds.are shown in Supplementary Materials)