Initially, the structure of 17a was investigated via 1 H NMR, which confirmed that a cyclization to the indole scaffold had occurred. Furthermore, the presence of the perfluorinated chain in the sample was confirmed via F NMR and the product mass could be confirmed using FAB-MS and HRMS measurements. However, at this point, it was still not clear at which position the fluorinated acyl moiety was attached to the indole core. The structure of 17a was further examined and confirmed by 2D NMR spectroscopy and single crystal X-ray diffraction (Figure ). The NMR-based characterization of the obtained structure included some interesting aspects due to presence of the fluorous tag and the need to exactly determine its attachment point to the indole core. The 13 C NMR signal corresponding to the C-5 carbon atom occurs as a triplet in the spectrum, while on the other hand, quaternary C-4 and C-3 carbons with less bond distance to the first CF2group appear as singlets in the 13 C NMR spectrum. This effect can be explained by the non-bonded proximity through space of the carbon and fluorine nuclei. Additional challenges were observed in the attempt to determine the centre of the 13 C signals in the fluorine tag which occur with complex multiplicity and a very low intensity due to the coupling of 13 C atoms to multiple F nuclei. To circumvent this and to understand the connectivity of 13 C to F nuclei, a 19 F{1H}-13 C{1H}-HSQC NMR spectrum was measured (Figure ). The spectrum clearly showed coupling of seven carbon nuclei with fluorine over one bond and chemical shifts of the involved carbon atoms could be determined, although the signals could not be clearly separated from each other and were difficult to identify in the 1D 13 C NMR spectra. The 19 F{1H}-13 C{1H}-HSQC NMR measurement was used to characterize all final compounds and was identified as a fast and reliable method to gain the required information on the centre of all 13 C nuclei in the isolated compounds. To improve the yield of the reaction from compound 15a to 17a, the conditions of the All reactions were performed at 21 °C under irradiation with λ = 465 nm. a 3 equiv. of base were added.