Experiments

All reactions were carried out under a positive atmosphere of Ar in dried glassware. Dehydrated solvents and materials were obtained from commercial suppliers and used without further purification unless otherwise noted. Column chromatography was performed on Fuji Silysia BW-200 silica gel or Kanto Kagaku Silica Gel 60 N (spherical, neutral) \(100 {-} 210\;\upmu {\text{m}}\) . Reactions and chromatography fractions were analyzed by thin-layer chromatography (TLC) carried out on Merck Silica Gel 60 F254 or Wako Silicagel 70 F254 TLC Plate-Wako with visualization by ultraviolet (UV) irradiation at 254 nm and/or indicated stains. IR spectra were measured on Shimadzu IRAffinity-1. The wave numbers of maximum absorption peaks of IR spectroscopy are presented in cm−1. All melting points were determined using a Yamato MP-21 melting point apparatus MP-J3 and are uncorrected. The 1H and 13C-NMR spectra were recorded on JEOL ECA-500 (1H, 500 MHz; 13C, 126 MHz). Chemical shifts are presented in ppm relative to tetramethylsilane (1H, 0.00) or solvents as follows: CDCl3 (13C, 77.0) (1H, 7.26). Abbreviations are as follows: s, singlet; d, doublet; dd, doublet of doublets; ddd doublet of doublets of doublets; t, triplet; td, triplet of doublets; q, quartet; qd, quartet of doublets; m, multiplet; br s, broad singlet; br dd, broad doublet of doublets; br m, broad multiplet. Low-resolution mass spectra (LRMS) were recorded on JEOL JMS-700 (FAB) with 3-nitrobenzylalcohol (NBA) as a matrix, or Shimadzu GCMS-QP2010 SE (EI) mass spectrometer. High-resolution mass spectra (HRMS) were recorded on JEOL JMS-700 (FAB), or Shimadzu LCMS-IT-TOF (ESI) mass spectrometer using MeOH as a mobile phase. Optical rotations were recorded on JASCO P-1030 polarimeter. High performance liquid chromatography (HPLC) analyses were performed on a SHIMADZU analytical system equipped with two LC-20AT pumps and a SPD-20A UV/Vis detector using YMC CHIRAL Amylose-SA column (250 × 4.6 mm) or Daicel Chiralpak AD-H column (250 × 4.6 mm). Preparative HPLC was performed on a YMC LC-forte/R using YMC CHIRAL Amylose-SA column (250 × 20 mm). X-ray diffraction data were recorded on a RIGAKU R-AXIS RAPID system.