3.5.3. Coupling of the First Amino Acid

After swelling the 2-CTC resin for 20 min in dry CH2Cl2 (2 mL), a solution of either Fmoc-L-Ala-OH or Fmoc-D-Ala-OH (1.2 eq.) and DIPEA (44 μL, 0.25 mmol, 2.5 eq.) in dry CH2Cl2 (2 mL) was added to the resin and mixed for 2 h. The resin was filtered and MeOH (200 μL) was added and mixed for 15 min to cap the resin. The resin was washed with dry CH2Cl2 (5 × 1 min), 1:1 CH2Cl2/MeOH (5 × 1 min) and MeOH (2 × 1 min).
