reductive amination of a-keto acids
Example: Make the dipeptide Ala-Leu
Problem with linking two amino acids together:
Now, react together
Merrifield Solid-Phase Technique
STEP 1: React a BOC-protected amino acid with the bromomethylated polystyrene.
STEP 2: Wash off excess reagent, and deprotect with trifluoroacetic acid.
STEP 3: React a second BOC-protected amino acid with the polymer-bound amino acid.
The cycle of deprotection, coupling, and washing is repeated as many times as desired to add amino acid units to the growing chain.
STEP 4: After the desired peptide has been made, treatment woth anhydrous HF removes the final BOC group and cleaves the ester bond to the polymer, yielding the free peptide.