1.7 mm tci microcryoprobe

NMR spectra were recorded on a Bruker Advance III HD 700 spectrometer, equipped with a cryoplatform and a 1.7 mm TCI microcryoprobe (Bruker Biospin GmbH, Rheinstetten, Germany). NMR tubes of 1.7 mm outer diameter were used for all measurements. All NMR spectra were recorded using MeOH-d₃ as a solvent. Chemical shifts were referenced to the residual solvent peaks at δ_H 3.31 and δ_C 49.15, respectively. Data acquisition and processing were accomplished using TopSpin 3.2. (Bruker Biospin). Standard pulse programs as implemented in TopSpin were used for data acquisition.

¹H‐NMR, ¹H,¹H‐PRESAT‐dqf‐COSY, ¹H,¹³C‐HSQC, ¹H,¹³C‐HMBC and ¹H,¹H‐PRESAT‐ROESY spectra were recorded using a Bruker Avance III HD 700 spectrometer equipped with a 1.7 mm TCI microcryoprobe and a cryoplatform (Bruker Biospin GmbH, Rheinstetten, Germany). NMR tubes of 1.7 mm outer diameter were used. All NMR spectra were recorded at 298 K using D₂O as a solvent. Spectrometer control was accomplished using Bruker TopSpin 3.2 software (Bruker Biospin). Standard pulse programs as implemented in TopSpin were used. For data processing, TopSpin 3.2 and ACD/Labs release 2012 (ACDLabs, Frankfurt, Germany) were used respectively. Prior to data acquisition, the spectrometer was carefully tuned to the transmitter frequencies for ¹H, ¹³C and ¹⁵N. Chemical shifts were left uncorrected.

LC/MS (liquid chromatography mass spectrometry) analyses were carried out on an Agilent 1200 Rapid Resolution HPLC system equipped with a SB-C8 column (2.1 × 30 mm, Zorbax) and coupled to a Bruker maXis mass spectrometer. Samples were subjected to LC/ESI-TOF analysis in order to determine their molecular formula. For the Nuclear Magnetic Resonance (NMR) analysis samples were dissolved in deuterated methanol (CD₃OD) and transferred to a 1.7 mm tube. Acquisitions were carried out on a Bruker AVANCE III 500 MHz spectrometer equipped with a 1.7 mm TCI Microcryoprobe. All spectra were recorded at 297 K. Structural elucidation of compounds was carried out by analysis of a combination of 1D (¹H and ¹³C), and 2D (¹H-¹H COSY, TOCSY, HSQC and HMBC) NMR experiments.