L-Phenylalanine, N-[(1,1-dimethylethoxy)carbonyl]- → L-Phenylalanine

Participants

Reaction Steps

6 g of Boc-Phe-PAM resin (substitution 0.36 mmol/g) was suspended and shaken in TFA/CH2Cl2 (1:1 by volume, 3×50 mL) 10 min. each time at room temperature to remove the Boc-group. The product was isolated by filtration and washed (3×50 mL each) with CH2Cl2 8% DIEA in CH2Cl2 and CH2Cl2 to give the free base of Phe-PAM-resin. This was subjected to sequential solid phase synthesis using the Fmoc-protocol. All couplings were performed using the DCC/HOBt procedure. At step 7 the Fmoc-amino acid, DCC, and HOBt were added with the corresponding reaction times as follows: Fmoc-Asp(OtBu)-OH (2.46 g, 6 mmol), DCC (1.24 g, 6 mmol) and HOBt (1.2 g, 9 mmol) were dissolved in 50 mL of 1:1 by volume DMF/CH2Cl2, and allowed to couple for 60 min at room temperature. Fmoc-Met-OH (2.2 g, 6 mmol), DCC (1.24 g, 6 mmol) and HOBt (1.2 g, 9 mmol) were dissolved in 50 mL of 1:1 by volume DMF/CH2Cl2, and allowed to couple for 60 min at room temperature. Fmoc-Trp-OH (2.6 g, 6 mmol), DCC (1.24 g, 6 mmol) and HOBt (1.2 g, 9 mmol) were dissolved in 50 mL of 1:1 by volume DMF/CH2Cl2, and allowed to couple for 60 min at room temperature. Fmoc-Gly-OH (1.8 g, 6 mmol), DCC (1.24 g, 6 mmol) and HOBt (1.2 g, 9 mmol) were dissolved in 50 mL of 1:1 by volume DMF/CH2Cl2, and allowed to couple for 60 min. Fmoc-Met-OH (2.2 g, 6 mmol), DCC (1.24 g, 6 mmol) and HOBt (1.2 g, 9 mmol) were dissolved in 50 mL of 1:1 by volume DMF/CH2Cl2, and allowed to couple for 60 min at room temperature. At this point the peptide-resin was dried under high vacuum to provide 7.98 g of Fmoc-Met-Gly-Trp-Met-Asp(OtBu)-Phe-PAM resin.

Provenance & Evidence