NMR Spectroscopy and Mass Spectrometry Protocol

¹H and ¹³C NMR spectra were recorded on a 400 MHz spectrometer Agilent 400-MR (Agilent Technologies, Santa Clara, CA, USA), 400.0 and 100.6 MHz for ¹H and ¹³C, respectively, at r.t. (room temperature) in CDCl₃ if not stated othewise; chemical shifts δ were measured with reference to the solvent (CDCl₃, δ_H = 7.26 ppm, δ_C = 77.16 ppm). When necessary, assignments of signals in NMR spectra were made using 2D techniques. Accurate mass measurements (HRMS) were obtained on a Bruker micrOTOF II (Bruker Daltonics, Billerica, MA, USA) with electrospray ionization (ESI). Analytical thin-layer chromatography was carried out with silica gel plates supported on aluminum (Macherey-Nagel, ALUGRAM^® Xtra SIL G/UV₂₅₄); the detection was carried out using a UV lamp (254 nm). Column chromatography was performed on silica gel (Macherey-Nagel, Silica 60, 0.015–0.04 mm), Rf (retardation factors) and solvent systems are given for each compound. 4-Chloropyrimidines 2a [44 (link)], 2b [45 (link)], 2d [46 (link)], 2e [47 (link)], 4-fluoropyrimidine N-oxide 6 [43 (link)] and 2-methyl-3,5,6,7,8,9-hexahydro-4H-cyclohepta[d]pyrimidin-4-one [48 (link)] were obtained via the described methods. All other starting materials were commercially available. All reagents except commercial products of satisfactory quality were purified according to the literature procedures, prior to use.