Introduction to Unnatural Foldamers - Metallofoldamers: Supramolecular Architectures from Helicates to Biomimetics - page 85

ribbons in g-peptides: crystal structures of gabapentin oligomers. Angew. Chem. Int. Ed. , 44 ,
4972-4975.
44. Hannessian, S., Luo, X., and Schaum, R. (1999) Synthesis and folding preferences of g-amino
acid oligopeptides: stereochemical control in the formation of a reverse turn and a helix.
Tetrahedron Lett. , 40 , 4925-4929.
45. Vasudev, P.G., Chatterjee, S., Shamala, N., and Balaram, P. (2011) Structural chemistry of
peptides containing backbone expanded amino acid residues: conformational features of b, g,
and hybrid peptides. Chem. Rev. , 111 , 657-687.
46. (a) For some very recent reviews see: Pils, L.K.A. and Reiser, O. (2011) a/b-Peptide fol-
damers: state of the art, b) Structural chemistry of peptides containing backbone expanded
amino acid residues: conformational features of b, g, and hybrid peptides. Amino Acids , 41 ,
709-718; (b) Horne, W.S., and Gellman, S.H. (2008) Foldamers with heterogeneous back-
bones. Acc. Chem. Res. , 41 , 1399-1408.
47. (a) De Pol, S., Zorn, C., Klein, C.D. et al. (2004) Surprisingly stable helical conformations in
a/b-peptides by incorporation of cis -b-aminocyclopropane carboxylic acids. Angew. Chem.
Int. Ed. , 43 , 511-514; (b) Hayen, A., Schmitt, M.A., Ngassa, F.N. et al. (2004) Two helical
conformations from a single foldamer backbone: “Split Personality” in short a/b-peptides.
Angew. Chem. Int. Ed. , 43 , 505-510.
48. (a) Baruah, P.K., Sreedevi, N.K., Gonnade, R. et al. (2007) Enforcing periodic secondary
structures in hybrid peptides: a novel hybrid foldamer containing periodic g-turn motifs.
J. Org. Chem. , 72 , 636-639; (b) Schramm, P., Sharma, G.V.M., and Hofmann, H.-J. (2009)
Helix formation in beta/delta-hybrid peptides: correspondence between helices of different
peptide foldamer classes. Biopolym. Pept. Sci. , 92 , 279-291; (c) Sharma, G.V.M., Shoban
Babu, B., Ramakrishna, K.V.S. et al. (2009) Synthesis and structure of a/d-hybrid peptides—
access to novel helix patterns in foldamers. Chem. Eur. J. , 15 , 5552-5566.
49. (a) Schmitt, M.A., Choi, S.H., Guzei, I.A., and Gellman, S.H. (2005) Residue requirements for
helical folding in short a/b-peptides: crystallographic characterization of the 11-Helix in an
optimized sequence. J. Am. Chem. Soc. , 127 , 13130-13131; (b) Choi, S.H., Guzei, I.A., and
Gellman, S.H. (2007) Crystallographic characterization of the a/b-peptide 14/15-Helix.
J. Am. Chem. Soc. , 129 , 13780-13781.
50. Bolin, K.A. and Millhauser, G.L. (1999) a and 3 10 : the split personality of polypeptide helices.
Acc. Chem. Res. , 32 , 1027-1033.
51. Sharma, G.V.M., Chandramouli, N., Choudhary, M. et al. (2009) a and 3 10 : the split personal-
ity of polypeptide helices. J. Am. Chem. Soc. , 131 , 17335-17344.
52. An early example was described by Karle, I.L., Pramanik, A., Banerjee, A. et al. (1997)
v-amino acids in peptide design. Crystal structures and solution conformations of pep-
tide helices containing a b-alanyl-g-aminobutyryl segment. J. Am. Chem. Soc. , 119 ,
9087-9095.
53. Baldauf, C., Gunther, R., and Hofmann, H.-J. (2006) Helix formation in a,g- and b,g-hybrid
peptides: theoretical insights into mimicry of a-andb-peptides. J. Org. Chem. , 71 ,1200-
1208.
54. Guo, L., Almeida, A.M., Zhang, W. et al. (2010) Helix formation in preorganized b/g-peptide
foldamers: hydrogen-bond analogy to the a-Helix without a-amino acid residues. J. Am.
Chem. Soc. , 132 , 7868-7869.
55. Sharma, G.V.M., Babu, B.S., Ramakrishna, K.V.S. et al. (2009) Synthesis and structure
of a/d-hybrid peptides - access to novel helix patterns in foldamers. Chem.Eur.J. , 15 ,
5552-5566.
56. (a) Harris, K.D.M. (1997) Meldola lecture: understanding the properties of urea and thiourea
inclusion compounds. Chem. Soc. Rev. , 26 , 279-289; (b) Cram, D.J. and Cram, J.M. (1997)
Container Molecules and their Guests , Royal Society of Chemistry, Cambridge.