General description

Hmb protection of amide bonds has been shown to inhibit aggregation of "difficult" peptides by Fmoc SPPS, thereby leading to products of increased purity ^{[1,2,3,4,5,6]}. Retention of Hmb groups on the cleaved peptide can greatly improve the solubility of protected peptide fragments ^[7,8] and otherwise intractable sequences^[9,10,11]. Furthermore, using a Hmb-protected derivative for incorporation of the residue linked to the carboxy group of Asp or Asn residues has been found to suppress formation of aspartimide and piperidide related by-products ^[12,11,14]. For a comparison of the efficiency of Hmb and pseudoprolines in preventing aggregation, see ^[15].

Associated Protocols and Technical Articles
Cleavage and Deprotection Protocols for Fmoc SPPS

Literature references

^[1] T. Johnson, et al. (1993) J. Chem. Soc., Chem. Commun., 369.
^[2] C. Hyde, et al. (1994) Int. J. Peptide Protein Res., 43, 431.
^[3] L. C. Packman, et al. (1994) Pept. Res., 7, 125.
^[4] T. Johnson, et al. (1994) Tetrahedron Lett., 35, 463.
^[5] R. G. Simmonds (1996) Int. J. Peptide Protein Res., 47, 36.
^[6] T. Johnson, et al. (1995) Lett. Pept. Sci., 1, 11.
^[7] M. Quibell, et al. (1995) J. Am. Chem. Soc., 117, 11656.
^[8] M. Quibell, et al. (1996) J. Chem. Soc., Perkin Trans. 1, 1227.
^[9] M. Quibell, et al. (1994) Tetrahedron Lett., 35, 2237.
^[10] M. Quibell, et al. (1994) J. Org. Chem., 59, 1745.
^[11] M. Quibell, et al. (1995) J. Chem. Soc., Perkin Trans. 1, 2019.
^[12] M. Quibell, et al. (1994) J. Chem. Soc., Chem. Commun., 2343.
^[13] L. C. Packman (1995) Tetrahedron Lett., 36, 7523.
^[14] J. Offer, et al. (1996) J. Chem. Soc., Perkin Trans. 1, 175.
^[15] W. R. Sampson, et al. (1999) J. Peptide Sci., 5, 403.

Linkage

Replaces: 04-12-1148

Analysis Note

Color (visual): white to slight yellow to beige
Appearance of substance (visual): powder
Identity (IR): passes test
Enantiomeric purity: ≥ 99.5 % (a/a)
Purity (TLC(157A)): ≥ 98 %
Purity (TLC(157B)): ≥ 98 %
Assay (HPLC, area%): ≥ 97.0 % (a/a)
Solubility (1 mmole in 2 ml DMF): clearly soluble

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