Sil g uv254 plates

All solvent used for reactions were dried and purified before by known methods. TLC on precoated silica gel SIL G/UV₂₅₄ plates (Macherey-Nagel & Co. Düren, Germany)) were used for the reaction monitoring. All apparatus used for the compound’s characterization were mentioned in our previous paper [41 ]

Melting points were measured on a Fisher-Johns apparatus (Fisher Scientific Company, Pittsburgh, PA, USA) and are uncorrected. Optical rotations were measured on a 323 polarimeter (Perkin Elmer Inc., London, UK). Ultraviolet absorptions were recorded on a UV 160U spectrophotometer (Shimadzu, Kyoto, Japan). IR spectra were obtained on a Tensor 27 spectrometer (Bruker, Ettlingen, Germany). The 1D and 2D NMR experiments were performed on a Bruker Advance III spectrometer (Bruker) at 400 MHz for ¹H and 100 MHz for ¹³C. Chemical shifts were referenced to TMS and J values are given in Hz. The HRDARTMS data were recorded on an AccuTOF JMS-T100LC mass spectrometer (Jeol Ltd., Tokyo, Japan). Prep TLC was carried out on precoated Sil G/UV254 plates (Macherey Nagel, Düren, Germany) of 1.0 mm thickness. Silica gel 230–400 mesh (Macherey-Nagel), Sephadex LH-20 (Pharmacia Biotech AB, Uppsala, Sweden) and octadecyl functionalized silica gel (Sigma Aldrich, St. Louis, MO, USA) were used for column chromatography. The X-ray data were collected on a D8 Venture κ-geometry diffractometer (Bruker).

All reactions were performed in flame-dried glassware under a nitrogen atmosphere. Reagents were obtained from commercial suppliers (Merck Srl, Milan, Italy) and used without further purification. TLC chromatography was performed on precoated aluminum silica gel SIL G/UV254 plates (Macherey-Nagel GmbH & Co. Düren, Germany). The detection occurred via fluorescence quenching or development in a ninhydrin solution (0.2 g of ninhydrin in 99.5 mL ethanol and 0.5 mL acetic acid.). Merck silica gel 60 was used for chromatography (23–400 mesh). ¹H NMR and ¹³C NMR spectra were measured on a Bruker Avance DRX400 (400 MHz/100 MHz) spectrometer. Chemical shifts for protons were reported in parts per million (ppm, δ scale) and internally referenced to the deuterated dimethyl sulfoxide (DMSO-d₆), methanol (CD₃OD) or chloroform (CDCl₃) signal at δ 2.50, 3.33 and 7.28 ppm, respectively. ¹H-NMR spectra are reported in this order: multiplicity and number of protons. Signals were characterized as: s (singlet); d (doublet); dd (doublet of doublets); t (triplet); m (multiplet); bs (broad signal). Mass spectra were recorded with an Agilent 1100 LC/MSD VL system (G1946C) (Agilent Technologies, Palo Alto, CA, USA).