Agilent 6320 ion trap mass spectrometer

Melting points (uncorrected) were recorded on a Barnstead 9100 Electrothermal melting apparatus (APS Water Services Corporation, Van Nuys, CA) while the IR spectra were recorded on a FT-IR Perkin-Elmer spectrometer (PerkinElmer Inc., Waltham, MA). The ¹H NMR and ¹³C NMR were measured in DMSO-d₆ or CDCl₃, on Bruker 700 or 500 and 176 or 125 MHz instruments, respectively (Bruker, Billerica, MA). Chemical shifts are reported in δ ppm. Mass spectra were recorded on an Agilent 6320 Ion Trap mass spectrometer (Agilent Technologies, Santa Clara, CA). C, H, and N were analysed at the Research Centre, College of Pharmacy, King Saud University, Saudi Arabia. The results were within ±0.4% of the theoretical values. Compounds 4, 8, 9, 12–17, and 22–24 were prepared according to a previously reported procedure⁶ (link)^b,24 (link).

An Agilent 6320 Ion trap mass spectrometer (Agilent technologies, USA) equipped with an electrospray ionization interface (ESI) was used. A connector is used instead of the column to allow direct injection of samples. Mobile phase was composed of a mixture of solvents A and B (1 : 1), where A is HPLC grade water and B is acetonitrile. Compounds were prepared by weighing the solid substances to 1 mg·mL⁻¹ in mobile phase. Test solutions were prepared by diluting the stock solutions to 10–30 μgmL⁻¹—depending on the ions intensities—with mobile phase. Flow rate was 0.2 mL min⁻¹ and run time was 4 minutes. MS parameters were optimized for each compound. The scan was ultrascan mode. For screening of mass signals of the different compounds and to search for parent ions for MS/MS experiments, MS2 scans were performed in the mass range of m/z 50–400. The ESI was operated in positive mode. The source temperature was set to 350°C nebulizer gas pressure of 55.00 psi, dry gas flow rate of 12.00 L min⁻¹.

Optical rotation: Perkin-Elmer Model 341 LC polarimeter (Perkin-Elmer, Waltham, MA, USA). UV spectra: in MeOH using a Perkin-Elmer Lambda 25 UV/VIS spectrophotometer (Perkin-Elmer, Waltham, MA, USA). IR spectra: Shimadzu Infrared-400 spectrophotometer (Shimadzu, Kyoto, Japan). ESIMS spectra: Agilent 6320 Ion trap mass spectrometer (Agilent Technologies, Santa Clara, CA, USA) equipped with an electrospray ionization interface. NMR spectra: Bruker DRX 700 spectrometer (Bruker, Rheinstetten, Germany). Column chromatographic separations: silica gel 60 (0.04–0.063 mm, Merck, Darmstadt, Germany). TLC analyses: pre-coated silica gel F254 aluminum sheets (Merck, Darmstadt, Germany).