Agilent 6540 accurate mass quadrupole time of flight mass spectrometer

Specific rotations were measured using JASCO P-2000 polarimeter. NMR spectra were obtained from Bruker DRX-400 NMR spectrometer equipped with Cryoprobe. The NMR spectrometer used a 5-mm BBI (¹H, G-COSY, multiplicity-edited G-HSQC, and G-HMBC spectra) or BBO (¹³C spectra) probe heads equipped with z-gradients. Agilent 1260 Infinity Preparative-Scale LC/MS Purification System equipped with Agilent 6130B single quadrupole mass spectrometer detector was used to conduct preparative HPLC analyses. Agilent 5 Prep C₁₈ column (10 mm × 30 mm) was used for HPLC runs. HPLC-MS experiment was performed on an Agilent UHPLC 1290 Infinity coupled with a diode array detector (DAD), and an Agilent 6540 accurate-mass quadrupole time-of-flight (QTOF) mass spectrometer equipped with a splitter and an ESI source. The analyses were conducted with Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) under standard gradient condition of 98% (0.1% formic acid) to 100% MeCN (0.1% formic acid) over 8.6 min, at a flow rate of 0.5 ml/min. The operating parameters for QTOF were the same as in (Sirota et al., 2018 (link)).

JASCO P-2000 digital polarimeter was used to record the optical rotations while GE Healthcare Ultrospec 9000 spectrophotometer was used to obtain the UV spectra.
Bruker DRX-400 NMR spectrometer with Cryoprobe was used to collect the NMR spectra. 5-mm BBI (¹H, G-COSY, multiplicity-edited G-HSQC, and G-HMBC spectra) or BBO (¹³C spectra) probe heads equipped with z-gradients were used.
Agilent 1260 Infinity Preparative-Scale LC/MS Purification System and Agilent 6130B single quadrupole mass spectrometer for LC and LC/MS Systems were used to perform the preparative HPLC analysis.
Agilent UHPLC 1290 Infinity coupled to Agilent 6540 accurate-mass quadrupole time-of-flight (QTOF) mass spectrometer which was equipped with a splitter and an ESI source were used to acquire the HRESIMS and MS/MS spectra. For over 15 min, under standard gradient condition of 100% water with 0.1% formic acid to 100% acetonitrile with 0.1% formic acid, the analysis was performed with a C18 4.6 × 75 mm, 2.7 μm column at flowrate of 2 mL/min. The operating parameters for QTOF were the same as in [6 (link)].
Nα-(2,4-Dinitro-5-fluorophenyl)-L-alaninamide (L-FDAA) and amino acid standards were purchased from Sigma Aldrich except D-allo-threonine which was purchased from Chem Cruz. Aspartic acid and glutamic acid were converted from asparagine and glutamine (Sigma Aldrich), respectively.

Several instruments were used to characterize the chemical properties of the compounds; for example, P-2000 digital polarimeter (JASCO) was used to measure the specific rotations of the compounds and Bruker DRX-400 NMR spectrometer with 5-mm BBI (1H, G-COSY, multiplicity-edited G-HSQC, and G-HMBC spectra) probe heads equipped with z-gradients and Cryoprobe was utilized to collect NMR spectra of the compounds. The ¹H chemical shifts were referenced to the residual solvent peaks for CDCl₃ at δ_H 7.26 ppm and (CD₃)₂CO at δ_H 2.05 and δ_C 29.8 ppm, respectively. C₁₈ reversed-phase preparative HPLC purification was conducted using Agilent 1260 Infinity Preparative-Scale LC/MS Purification System coupled to Agilent 6130B single quadrupole mass spectrometer with Agilent 5 Prep C18 column (100 × 30 mm, 5 µm). HPLC-MS analyses were conducted using Agilent UHPLC 1290 Infinity coupled to Agilent 6540 accurate-mass quadrupole time-of-flight (QTOF) mass spectrometer and an ESI source. Gradient elution that starts from 98% water with 0.1% formic acid to 100% acetonitrile with 0.1% formic acid over 8.6 min along with an Acquity UPLC BEH C₁₈ (2.1 × 50 mm, 1.7 µm) column at a flow rate of 0.5 mL/min was used. The operating parameters for QTOF were the same as previously reported [45 (link)].