RODRIGUES, L. M.; FONSECA, J. I.; MAIA*, H. L. S.; Tetrahedron 60 (2004) 40, 8929-8936; Dep. Quim., Univ. Minho, P-4710 Braga, Port.; Eng.) -Jannicke 52-175

Tetrapeptides containing one of a set of four different a,a-dialkyl glycines at the C-terminus were synthesized by conventional methods in solution and their conformational behavior investigated by 1 H NMR spectroscopy in connection with molecular mechanics calculations. The results were consistent with conformations stabilized by a g-turn in the case of compounds with alkyl groups larger than methyl, while the corresponding Aib derivative did not exhibit intramolecular hydrogen bonding. q