The other approach is to introduce backbone protecting groups which will prevent the formation of hydrogen bonds. Such protection is made by the introduction of the Hmb group on the αnitrogen . It has been shown that the presence of a Hmb unit every 6-7 residues is sufficient to disrupt the peptide aggregation . The Hmb protected amino acid is introduced under the form of N,O-bis-Fmoc-N-(2hydroxy-4-methoxybenzyl) derivative, the O-Fmoc protection being cleaved during the following piperidine treatment. At the end of the synthesis the Hmb group is cleaved in the final TFA cleavage.
The use of Fmoc chemistry for protection of the alpha amino group has become the preferred method for most contemporary solid and solution phase peptide synthetic processes. Fmoc has also been shown to be more reliable and produce higher quality peptides than Boc chemistry.
is a protecting group used in organic synthesis ..
Before the Fmoc group became popular, the t-Boc group was commonly used for protecting the terminal amine of the peptide, requiring the use of more acid stable groups for side chain protection in orthogonal strategies. Boc groups can be added to amino acids with Di-tert-butyl dicarbonate (Boc anhydride) and a suitable base.