Drx 400 avance spectrometer

Monitoring of reaction progress was performed by analytical thin-layer chromatography (TLC) on aluminium sheets precoated with silica gel (Type 60 F254, 0.25 mm; from Merck, Darmstadt, Germany). NMR spectra were measured on a BRUCKER DRX-400 AVANCE spectrometer using dimethylsulfoxide (DMSO-d₆) or chloroform (CDCl₃) as solvents. Chemical shifts are expressed in parts per million (ppm) and multiplicities of ¹H NMR signals were labelled as follows: s: singlet; d: doublet; t: triplet; q: quartet; and m: multiplet and coupling constants were expressed in hertz (Hz). Elemental analyses were performed on a Carlo–Erba CHNS apparatus. The purity of the compounds 4a–i was checked and confirmed to be >95% by elemental analyses, conducted on a Carlo–Erba EA 1108. These compounds were also found to be ≥95% pure by HPLC analysis using a Hitachi Chromaster instrument equipped with a BDS Hypersil C18 column (4.6 mm × 250 mm, Ø = 5 μm). The mobile phase is a mixture of methanol—and aqueous potassium phosphate 0.1 g% and phosphoric acid at 85% at 0.05 g% (60:40, v/v), and peaks were detected at 230 nm (see chromatograms of 4a and 4f in the Supporting Information)

Melting points (°C) were determined with a Kofler hot bench and are uncorrected. Analytical thin-layer chromatography (TLC) on silica-gel-precoated aluminum sheets (Type 60 F254, 0.25 mm thickness; from Merck, Darmstadt, Germany) was employed to follow the progress of the reactions and to check the purity and homogeneity of the synthesized products. Nuclear magnetic resonance spectra (NMR) were recorded on a BRUCKER DRX-400 AVANCE spectrometer (at 400 MHz for ¹H and 100 MHz for ¹³C), using dimethylsulfoxide (DMSO-d6) as the solvent and tetramethylsilane (TMS) as the internal standard. The chemical shifts are expressed in parts per million (ppm) and the multiplicities of ¹H NMR signals were designated as follows: s: singlet; d: doublet; t: triplet; q: quartet; and m: multiplet, and coupling constants were expressed in hertz (Hz). High-resolution mass spectra (HRMS) were recorded using a Bruker micrOTOF-Q II spectrometer (Bruker Daltonics) in positive electrospray ionization time-of-flight mode at UCA Clermont Ferrand, France.

Melting points (°C) were determined with a Kofler hot bench and were uncorrected. Analytical thin-layer chromatography (TLC) on silica-gel-precoated aluminum sheets (Type 60 F254, 0.25-mm thickness; from Merck, Darmstadt, Germany) was employed to follow the progress of the reactions and to check the purity and homogeneity of the synthesized products. Nuclear-magnetic-resonance spectra (NMR) were recorded on a Brucker DRX-400 Avance spectrometer (at 400 MHz for ¹H and 100 MHz for ¹³C), using dimethylsulfoxide (DMSO-d₆) as the solvent and tetramethylsilane (TMS) as internal standard. The chemical shifts are expressed in parts per million (ppm) and the multiplicities of ¹H NMR signals were designated as follows: s: singlet; d: doublet; t: triplet; q: quartet; and m: multiplet. Coupling constants were expressed in hertz (Hz). High-resolution mass spectra (HRMS) were carried out by using a Bruker micrOTOF-Q II spectrometer (Bruker Daltonics) in positive electrospray ionization time-of-flight at UCA Clermont Ferrand, France.