Identify the steps you would use to combine Val-Leu and

Step 1 of 2

In this exercise, we’re asked to identify the steps we'd use to combine Val-Leu and Phe-Ile to form the tetrapeptide Phe-Ile-Val-Leu. By convention, when writing out a peptide sequence the N terminus is written first, and the C terminus is at the end of the sequence.

Recall that N,N'-dicyclohexyldiimide (DCC) is a dehydrating agent that can form an amide linkage between an amine group and a carboxylic acid. However, because each individual peptide contains both an amine and a carboxylic acid, amine protecting group chemistry is necessary to ensure that the correct sequence is formed. We can use di-tert-butyl-di-carbonate to temporarily protect an amine group, and a Fischer esterification with methanol will suffice to temporarily protect a carboxyl group.