Pseudoproline dipeptides[1-4], developed by Mutter for bypassing the synthesis difficulties in preparing long peptides, cyclic peptides or segments with limited solubility, have been widely applied in current peptide synthesis due to their remarkable solubilizing effects. The advantages of the serine and threonine derived pseudoproline dipeptides could be summarized as follows: 1) They can be coupled to growing chains using standard procedures and coupling reagents; 2) they are compatible with most common peptide synthesis strategies including Fmoc- and Z-amino acids; 3) They can be easily cleaved by standard TFA mixture.
 Mutter M., Nefzi A., Sato T., Wahl F., Wöhr T. Pept. Res.1995, 8, 145.
 Wöhr T., Rohwedder B., Wahl F., Nefzi A., Sato T., Sun X., Mutter M. J. Am. Chem. Soc. 1996, 118, 9218.
 Sampson W. R., Patsiouras H., Ede N. J. J. Pept. Sci. 1999, 5, 403.
 Dumy P., Keller M., Ryan D. E., Rohwedder B., Wöhr T., Mutter M. J. Am. Chem. Soc. 1997, 119, 918.