Ap 300 digital polarimeter

An Atago AP-300 digital polarimeter with a 1 dm microcell and a sodium lamp (589 nm) was used to obtain optical rotations. A Bruker DRX-600 NMR spectrometer (Bruker BioSpin GmBH, Rheinstetten, Germany) equipped with a Bruker 5 mm TCI at 300 K was employed to run NMR data. Data processing was carried out with Topspin 3.2 software. All 2D NMR spectra were acquired in methanol-d₄ (99.95%, Sigma-Aldrich, Milano, Italy), and standard pulse sequences and phase cycling were used for COSY, HSQC, HMBC, 1D-TOCSY, and ROESY spectra. HRESIMS data were obtained in the positive ion mode on a Q Exactive Plus mass spectrometer, an Orbitrap-based FT-MS system, equipped with an ESI source (Thermo Fischer Scientific Inc., Bremen, Germany). Column chromatography was performed over silica gel (70–220 mesh, Merck). A Shimadzu LC-8A series pumping system equipped with a Shimadzu RID-10A refractive index detector and Shimadzu injector (Shimadzu Corporation, Kyoto, Japan) on a Waters XTerra Semiprep MS C₁₈ column (300 mm × 7.8 mm i.d.) and a mobile phase consisting of a MeOH-H₂O mixture at a flow rate of 2.0 mL/min were employed to purify the molecules. TLC was performed on silica gel 60 F₂₅₄ (0.20 mm thickness) plates (Merck, Darmstadt, Germany) as a spray reagent, and Ce(SO₄)₂/H₂SO₄ (Sigma-Aldrich, Milano, Italy) was used [60 (link)].

RMN spectroscopic analysis was utilized. The ¹H- and ¹³C-NMR spectra were recorded in CDCl₃ solutions and are referenced to the residual peaks of CHCl₃ at δ = 7.26 ppm and δ = 77.00 ppm for ¹H and ¹³C on an Avance 400 Digital NMR spectrometer (Bruker, Rheinstetten, Germany) operating at 400.1 MHz for ¹H and 100.6 MHz for ¹³C.
Optical rotation was measured with a sodium lamp (λ = 589 nm, D line) on a Atago AP-300 digital polarimeter equipped with 1 dm cells at 23 °C.