Drx 500 ft nmr spectrometer

UV spectra were obtained using a Shimadzu Pharmaspec-1700 UV-Visible spectrophotometer. Optical rotations were measured with a Jasco-DIP-180 polarimeter (JASCO, Inc., Tokyo, Japan). Infrared spectra were recorded on a Perkin-Elmer-983G FT-IR spectrophotometer (PerkinElmer Ltd., Bucks, UK). 1D- and 2D-NMR spectra were measured with a Varian-Unity-Plus-400 spectrometer or a Bruker DRX-500 FT-NMR spectrometer with tetramethylsilane (TMS) as the internal standard (Bruker Instruments, Karlsruhe, Germany). EI-MS and HR-EI-MS were measured with a JEOL SX-102A mass spectrometer and a Finnigan TSQ-46C mass spectrometer, respectively (Finnigan MAT, Inc., San Jose, CA, USA). Column chromatography was performed using Merck Si gel (230–400 mesh; Merck & Co., Inc., White House Station, NJ, USA), and TLC (thin-layer chromatography) analysis was carried out using aluminum pre-coated Si plates (Silica Gel 60 F-254; Merck & Co., Inc.); the spots were detected by spraying with 5% H₂SO₄ and then heating at 100 °C. Semi-preparative HPLC was performed using a normal phase column (LiChrosorb Si 60, 7 μm, 250 mm × 10 mm; Merck & Co., Inc.) on a LDC Analytical-III system.

All chemicals, including caffeic acid, N,N-dimethylformamide, trimethylamine, BOP, CH₂Cl₂, EtOAc, HCl, thionyl chloride, SOCl₂, NaHCO₃ (aq.), and MgSO₄, were of analytical-grade purity. They were purchased from the branch of Merck in Taipei, Taiwan, and the branch of Sigma Aldrich in Taichung, Taiwan. UV spectra were recorded on a Shimadzu UV-1601PC spectrophotometer. Infrared (IR) spectra were measured on a Perkin-Elmer-983G FT-IR spectrophotometer. ¹H- and ¹³C-NMR and 2D NMR spectra were obtained on a Bruker DRX-500 FT-NMR spectrometer with tetramethylsilane (TMS) as the internal standard. EI-MS were measured with a Jeol-JMSHX300 mass spectrometer. Silica gel (230–400 mesh; Merck & Co., Inc.) was used for column chromatography (CC). Pre-coated Silica gel (60 F-254; Merck & Co., Inc.) plates were used for TLC. The spots on TLC were detected by spraying with 5% H₂SO₄ and then heating at 100 °C.

All melting points reported were uncorrected. ¹H and ¹³C NMR spectra were measured with a Bruker DRX 500 FT-NMR spectrometer in CDCl₃ or CD₃OD at 500 and 125 MHz, respectively. Chemical shifts were relative to tetramethylsilane as an internal standard. The coupling constants are given in Hz. Mass spectra were obtained on Waters Xevo QTOF (MS-A) and Shimadzu LCMS-IT-TOF (MS-B) mass spectrometers. IR spectra were recorded with a JASCO FT-IR 480 Plus infrared spectrometer. Optical rotations were determined with a JASCO DIP-1000 polarimeter. HPLC data were recorded with GL Science GL-7400 (HPLC-A), Shimadzu HPLC LC-VP series (HPLC-B) and Waters ACQUITY UPLC (HPLC-C).