2 chlorotrityl resin

Fmoc protected amino acids, 2‐chlorotrityl resin, O‐benzotriazole‐N,N,N,N‐tetramethyl‐uronium‐hexafluoro‐phosphate (HBTU), and 1‐hydroxy‐7‐azabenzotriazole (HOAt) were purchased from GL Biochem (Shanghai) Ltd. All solvents and the other chemicals were purchased from Merck, at analytical grade. High purity Milli‐Q‐water with a resistivity greater than 18 M Ω cm was obtained from an in‐line Millipore RiOs/Origin system. ¹H‐NMR and ¹³C‐NMR spectra were recorded at 400 MHz on a Varian Innova Instrument with chemical shift reported as ppm (with tetramethylsilane as internal standard). ESI‐MS spectra were recorded on an Agilent 6120 single quadrupole LC‐MS system. Optical microscope images were acquired on a Leitz Labovert instrument with a 20× magnification objective on a drop of fresh samples deposited on a clean glass slide.

2-Chlorotrityl resin, O-benzotriazole-N,N,N,N′-tetramethyl-uronium-hexafluoro-phosphate (HBTU), and Fmoc-protected amino acids were purchased from GL Biochem (Shanghai, China) Ltd. All solvents were purchased of analytical grade from Merck. Piperidine, trifluoroacetic acid (TFA), N,N-diisopropyl ethyl amine (DIPEA), and triisopropyl silane (TIPS) were from Acros (Milan, Italy). Sodium dihydrogen phosphate and disodium hydrogen phosphate were from BDH AnalaR (Milan, Italy). High-purity Milli-Q-water (MQ water) with a resistivity greater than 18 MΩ·cm was obtained from an in-line Millipore RiOs/Origin system.