The t‐butoxy group, a novel hydroxyl‐protecting group for use in peptide synthesis with hydroxy‐amino acids

We have found a novel way of protecting the hydroxyl function in hydroxy‐L‐amino acids, making use of the t‐butoxy group, which is readily split by acids, but not by bases. This group is introduced by acid‐catalysed addition of isobutene to N‐acylated hydroxy‐L‐amino acids. The blocking group is easily removed at or below room temperature with trifluoroacetic acid without racemization and without breaking peptide bonds 1,2