3.1. Chemistry. General information. All commercially available starting materials, reagents, and (anhyd.) solvents were used without further purification. Reaction controls were performed by thin-layer chromatography (TLC) on Macherey-Nagel precoated 60 F254 silica plates. Spots were visualized either by ultraviolet (UV) light (254 nm/365 nm) or staining solutions. Flash column chromatography was carried out using Grace Davison Davisil LC60A (20-45 μm) or Merck Geduran Si60 (mesh 63-200 μm) with an Interchim PuriFlash 430 automated flash chromatography system. NMR spectra were recorded on a Bruker Avance 400 MHz spectrometer at ambient temperature. Chemical shifts (δ) are reported in parts per million (ppm) relative to the internal control tetramethylsilane (TMS) and the spectra were calibrated against the residual solvent peak of the used deuterated solvent. Coupling constants (J) are expressed in Hertz (Hz). Purities of final compounds were determined by RP-HPLC using an Agilent 1100 Series LC with a Phenomenex Luna C8 analytical column (150 × 4.6 mm, 5 μm) and detected by a UV DAD detector at 254 nm wavelength. Elution was carried out with the following gradient: (A = 0.01 M KH2PO4, pH 2.30, B = MeOH) 40% B to 85% B in 8 min, 85% B for 5 min, 85% to 40% B in 1 min, 40% B for 2 min, stop time 16 min, flow 1.5 mL/min. Standard mass spectra were obtained from an Advion expression compact mass spectrometer (electron spray ionization, ESI) with a TLC plate reader system (using the following settings: ESI voltage 3.50 kV, capillary voltage 187 V, source voltage 44 V, capillary temperature 250 °C, desolvation gas temperature 250 °C, gas flow 5 L/min). All final compounds are ≥ 95% pure by HPLC. General procedure A for the synthesis of carboxamides. HATU (2.4 mmol, 1.2 equiv.) was added sequentially at 0 °C to the solution of the acid (2 mmol, 1 equiv.) in DMF (5 mL). The solution was kept at 0 °C for 30 min. After that, DIPEA (6 mmol, 3 equiv.) and the amine (2 mmol, 1 equiv.) were slowly added. The mixture was stirred at 0 °C for 1 h and at 25 °C for 12 h. The reaction was quenched by adding water and extracted with EtOAc (3 × 15 mL). The combined organic phases were washed with sat. NH4Cl solution (2 × 50 mL), sat. NaHCO3 solution (2 × 50 mL) and brine (2 × 50 mL). The organic layer was dried over Na2SO4 and concentrated under reduced pressure to the dryness.