Agilent 6220 esi tof ms instrument

General methods
1 H-, 13 C-and 19 F-NMR spectra (see ESI †) were recorded at room temperature using a JEOL ECX 400 (JEOL, Tokyo, Japan), a JEOL ECP 500 (JEOL, Tokyo, Japan) or a Bruker AVANCE III 700 (700 MHz, BRUKER, Billerica, MA, USA). Chemical shifts δ are reported in ppm with the solvent resonance (MeOH-d 4 ) as the internal standard. HRMS were determined on an Agilent 6220 ESI-TOF MS instrument (Agilent Technologies, Santa Clara, CA, USA). For analysis, the MassHunter Workstation Software Version B.02.00 (Agilent Technologies, Santa Clara, CA, USA) was used. IR Spectra were recorded on an ALPHA II FT-IR spectrometer (Bruker, USA). All NMR and IR spectra were evaluated by using Mnova/Mestrenova (Mestrelab Research, CA, USA). Elemental analysis was proceeded by use of an VARIO EL elemental analyzer (Elementar Analysensysteme GmbH, Langenselbold, Germany). All essential data for compound characterization is placed within the ESI. † All chemicals were purchased from commercial sources (Merck, Sigma-Aldrich, VWR, Fluorochem) and used without further purification. The Fmoc-protected fluorinated amino acid TfeGly was synthesised according to literature (see ESI, † chapter "Gram scale synthesis and characterization of fluorinated amino acid Fmoc-TfeGly-OH"). MfeGly and DfeGly were synthesised by Suvrat Chowdhary and Thomas Hohmann.