Agilent lc esi ms system

All chemicals were purchased from commercial vendors and used directly without further purification. All reactions requiring anhydrous conditions were carried out under argon atmosphere using oven-dried glassware. AR-grade solvents were used for all reactions. Reaction progress was monitored by TLC on pre-coated silica plates (Merck 60 F254 nm, 0.25 μm) and spots were visualized by UV, iodine or other suitable stains. Flash column chromatography was done using silica gel (Qingdao Ocean company). ¹H and ¹³C NMR spectra were recorded on a Bruker AV-400 spectrometer at 400 and 101 MHz, respectively. Coupling constants (J) are expressed in hertz (Hz). Chemical shifts (δ) of NMR are reported in parts per million (ppm) units relative to internal control (TMS). Mass spectra were obtained on Agilent LC‒ESI-MS system. High resolution ESI-MS were recorded on an AB SCIEX X500r QTOF mass spectrometer. Purity of compounds was determined by reverse-phase high performance liquid chromatography (HPLC) analysis to be >95%. HPLC instrument: Dionex Summit HPLC (column: Diamonsil C18, 5.0 μm, 4.6 mm × 250 mm (Dikma Technologies); detector: PDA-100 photodiode array; injector: ASI-100 autoinJector; pump: p-680A). A flow rate of 1.0 mL/min was used with mobile phase of MeOH in H₂O.