Mat 95 xl mass spectrometer

All reagents and solvents were purchased from commercial sources (Sigma-Aldrich, St. Louis, MO, USA) and used without purification. All reactions were monitored by thin layer chromatography (TLC) on TLC precoated silica gel 60 F254 glass-backed plates (Merck KGaA, Darmstadt, Germany). Flash column chromatography was performed on silica gel (200–300 mesh) (Merck KGaA, Darmstadt, Germany). Melting points were measured on a SMP3 apparatus (Stuart-Scientific, now Merck KGaA, Darmstadt, Germany) and are uncorrected. Refractive index values of the samples used in the experiment were measured using Abbe’s refractometer (Krüss, Hamburg, Germany). IR spectra were recorded as KBr disks in a FT-IR 6700 spectrometer (Nicolet, Thermo Scientific, San Jose, CA, USA) and frequencies are reported in cm⁻¹. The ¹H, ¹³C, 13C DEPT-135, gs 2D HSQC, and gs 2D HMBC spectra were recorded in CDCl₃ solutions and are referenced to the residual peaks of CHCl₃ at δ = 7.26 ppm and δ = 77.0 ppm for ¹H and ¹³C, respectively, on an Avance 400 Digital NMR spectrometer (Bruker, Rheinstetten, Germany) operating at 400.1 MHz for ¹H and 100.6 MHz for ¹³C. HRMS were recorded in a MAT 95 XL mass spectrometer (Thermo Finnigan, Bremen, Germany). The natural compound 2′,4′-dihydroxychalcone was purified from the resinous exudate of Adesmia balsamica as reported previously [12 (link)].

(S)-Perillyl alcohol, pyrocatechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol and the others chemicals used were of reagent grade and were obtained from Aldrich (St. Louis, MO, USA). The reaction progress was monitored by thin layer chromatography on silica gel 60 F-254 (Merck, Darmstadt, Germany), and components were visualized by a VL-4LC UV lamp (Vilber Lournat, Collégien, France). Purification by flash chromatography was performed on silica gel 60 (particle size 0.032–0.063 mm) also from Merck and recrystallization. Melting points were measured on a SMP3 apparatus (Stuart-Scientific, Staffordshire, UK). FT-IR spectra were recorded on Buck Scientific M500 instrument (Buck Scientific Instrument, East Norwalk, CT, USA). NMR spectra were recorded at room temperature in solution on a 400 MHz Avance instrument (Bruker, Rheinstetten, Germany). HRMS spectra were recorded on a MAT 95 XL mass spectrometer (Thermo Finnigan, Bremen, Germany).