Waters sqd 3100

All chemicals were purchased from commercial sources and were used without purification. Water was purified (18 MΩ cm) using a standard Milli-Q system (Millipore, Bedford, MA, USA). “PE” (petroleum ether) refers to petroleum ether with a boiling point in the range of 40–60 °C. NMR spectra (including ¹H-decoupled ¹³C NMR) were recorded on a Bruker Avance III spectrometer (Bruker, Milano, Italy) operating at 11.74 T and 298 K, corresponding to a protonic resonance frequency of 499.8 MHz. ¹H and ¹³C NMR chemical shifts are reported relative to TMS and are referenced using the residual proton solvent resonances. Samples were prepared in 5 mm NMR tubes by dissolving the compounds in appropriate deuterated solvents. Splitting patterns are described as singlet (s), broad singlet (bs), doublet (d), double doublet (dd), triplet (t) or multiplet (m). ESI mass spectra were recorded on a Waters SQD 3100 (Waters Corporation, Milford, MA, USA). Analytical HPLC-MS was carried out on a Waters modular system equipped with Waters 1525 binary pump, Waters 2487 UV/Vis and Waters SQD 3100 (ESCI ionization mode) detectors using an XBridge^TM Phenyl 3.5 μm 4.6 mm × 150 mm column (Waters). Semi-preparative HPLC purifications were performed with a XBridge^TM Prep Phenyl 5 μm OBD^TM 19 mm × 100 mm column (Waters). The HPLC methods are indicated for each procedure (Table 4).