Agilent 6520 q tof lc ms mass spectrometer

Optical rotations were measured on a Perkin-Elmer 241 polarimeter (Perkin-Elmer, Waltham, MA, USA). IR data were recorded using a Nicolet Magna-IR 750 spectrophotometer (Nicolet Instrument Company, Madison, WI, USA). 1D and 2D NMR spectra were recorded on a Bruker AV-600 spectrometer (600 MHz for ¹H and 150 MHz for ¹³C, respectively, Bruker Biospin, Fallanden, Switzerland), using tetramethylsilane (TMS) as an internal standard. HR-ESI-MS were measured by an Agilent 6520 Q-TOF LC-MS mass spectrometer (Agilent Technologies, Santa Clara, CA, USA). Analytical TLC were run on silica gel plates (GF₂₅₄, Yantai Institute of Chemical Technology, Yantai, China). Spots were observed under UV light and visualized by spraying with 10% H₂SO₄ in ethanol, followed by heating. Column chromatography (CC) was performed on silica gel (200–300 mesh, Qingdao Marine Chemical Factory, Qingdao, China) and Sephadex LH-20 (Amersham Biosciences, Uppsala, Sweden). Acarbose was purchased from Sigma-Aldrich (St. Louis, MO, USA).

Optical rotation data were measured on an Anton Paar MCP 200 Analytical Automatic Polarimeter (Anton Paar GmbH, Graz, Austria). IR data were recorded using a Nicolet Magna-IR 750 spectrophotometer (Thermo Scientific, San Jose, CA, USA). NMR spectra were recorded on AV-600 spectrometer (Bruker, Fällanden, Switzerland). ¹H-¹H COSY, HSQC, HMBC, and NOESY spectra were measured with the pulse sequence cosygpqf, hsqcetgpsi2, hmbcgpndqf, and noesygpph, respectively (standard sequence, Bruker TOPSPIN 3.1 software) (Bruker, Fällanden, Switzerland). The mixing time (D8) of NOESY spectra was 400 ms. HR-ESI-MS were measured by an Agilent 6520 Q-TOF LC-MS mass spectrometer (Agilent Technologies Co., Ltd., Palo Alto, CA, USA). Analytical and preparative TLC were run on silica gel plates (GF₂₅₄, Qingdao Haiyang Chemical Co., Ltd., Qingdao, China). Spots were visualized by spraying with 10% H₂SO₄, followed by heating. Column chromatography (CC) was performed on silica gel (200-300 mesh, Qingdao Haiyang Chemical Co., Ltd., Qingdao, China) and Sephadex LH-20 (Pharmacia Fine Chemical Co., Ltd., Uppsala, Sweden). Acarbose was purchased from Sigma-Aldrich (St. Louis, MO, USA).