1200 lc instrument

Commercially available compounds were used without further purification. Solvents were dried according to standard procedures. Column chromatography was performed with silica gel (200–300 mesh). The melting points were determined with an XT-4 melting point apparatus and were not corrected. ¹H NMR spectra were measured with a Bruker Ascend 400 MHz spectrometer (Karlsurhe, Germany) and the chemical shifts were reported in δ (ppm) relative to tetramethylsilane (TMS) as the internal standard. ¹³C NMR spectra were measured at 100 MHz with a 400 MHz spectrometer, and the chemical shifts were reported in ppm relative to tetramethylsilane and referenced to the solvent peak (CDCl₃, δC = 77.00 ppm; CD₃OD, δC = 49.05 ppm; acetone-d6, δC = 30.83 ppm). High-resolution mass spectra were measured with an Agilent 6520 Accurate-Mass Q-TOF MS system (Beijing, China), equipped with an electrospray ionization (ESI) source. Optical rotations were measured with a Krüss P8000 polarimeter (Beijing, China) at the indicated concentration with units of g/100 mL. Enantiomeric excesses were determined by chiral HPLC analysis, using an Agilent 1200 LC instrument (Beijing, China) with a Daicel Chiralpak IA, IB, IC, or AD-H column.

Commercially available compounds were used without further purification. Solvents were dried according to standard procedures. Column chromatography was performed with silica gel (200~300 mesh). Melting points were determined with an XT-4 melting-point apparatus and were uncorrected. ¹H NMR spectra were measured with Bruker Ascend 400 MHz spectrometer; chemical shifts were reported in δ (ppm) units relative to tetramethylsilane (TMS) as internal standard. ¹³C NMR spectra were measured at 100 MHz with 400 MHz spectrometer; chemical shifts were reported in ppm relative to tetramethylsilane and referenced to solvent peak (CDCl₃, δ C = 77.00). High-resolution mass spectra (Electron spray ionization) were measured with an Agilent 6520 Accurate-Mass Q-TOF MS system equipped with an electrospray ionization (ESI) source. Optical rotations were measured with a Krüss P8000 polarimeter at the indicated concentration with the units of g/100 mL. Enantiomeric excesses were determined by chiral HPLC analysis using an Agilent 1200 LC instrument with a Daicel Chiralpak IA, IC, or ADH column. ¹H and ¹³C NMR spectra for newly synthesized compounds, X-ray single crystal data for product 3ja and copies of the HPLC chromatograms can be found in the Supplementary Materials.