Ultra fast liquid chromatography spectrometry system

The ¹H NMR and ¹³C NMR spectra were recorded on a Bruker ARX (Bruker, Rheinstetten, Germany) 400 MHz or Bruker AMX 400 MHz or 600 MHz spectrometer in dimethyl sulfoxide (DMSO-d₆) if not noted otherwise, and the chemical shifts were expressed as ppm using trimethylsilane (TMS) as an internal reference. High-resolution mass spectral (HRMS) analyses were measured on a TripleTOF™ Mass Spectrometer (TripleTOF 5600, SCIEX, Foster City, CA, USA). Daphnetin and its derivatives were analyzed using an ultra-fast liquid chromatography spectrometry system (Shimadzu, Kyoto, Japan) equipped with two LC-20AD pumps, a DGU-20A3 vacuum degasser, a SIL-20ACHT auto-sampler, a CTO-20AC column oven, and an SPD-M 20A diode-array detector (DAD). All the reagents used in the synthesis were obtained commercially and used without further purification. The reactions were monitored using thin layer chromatography (TLC) on glass packed precoated silica gel GF₂₅₄ plates. Flash column chromatography was performed using silica gel (200–300 mesh), which was purchased from the Qingdao Ocean Chemical Co., Ltd (Qingdao, China). Daphnetin and 11 were purchased from Chengdu Pufei De Biotech Co., Ltd. (Sichuan, China).