Microtof focus 2 mass spectrometer

Compounds Lin1 and Fus4 were commercially available, whereas Compounds Lin2, Lin3, and Fus2 were produced by synthesis (reaction schemes and individual details of the synthetic procedure are indicated in Methods S1). Reagents and solvents were obtained from commercial suppliers and used without further purification, unless otherwise stated. Reactions were carried out under a positive atmosphere of nitrogen, unless otherwise stated. Reactions were monitored by thin layer chromatography (TLC) carried out on Merck TLC Silica gel 60 F₂₅₄, using shortwave UV light as the visualizing agent and phosphomolybdic acid in EtOH and heat as developing agent. Flash column chromatography was performed using Kanto Chemical Silica gel 60 N (spherical, 40–50 μm). ¹H NMR spectra were recorded on Varian Unity Plus 400 MHz spectrometer or Bruker Avance III HD 500 MHz spectrometer and were calibrated using residual undeuterated solvent as the internal references (CDCl₃: 7.26 ppm; MeOH-d₄: 3.31 ppm, acetone-d₆: 2.05 ppm; DMSO-d₆: 2.50 ppm). The following abbreviations were used to explain NMR peak multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, p = pentet, m = multiplet, br = broad. Low-resolution and high-resolution mass spectra were recorded on Bruker micrOTOF focus II mass spectrometer using electrospray ionization time-of-flight (ESI-TOF) reflectron experiments.