Table 2. Amide proton temperature coefficients indicating intramolecularly H-bonded protons in diastereomeric norbornapeptides 1–9 a .
| 1 | 2 | 3 b | 4 | 5 | 6 | 7 b | 8 | 9 | |
| l/d-Leu1-HN | 7.3 | 8.1 | 3.7 | 7.7 | 7.8 | 8.5 | 6.8 | 7.8 | 7.2 |
| Gly2-HN | 7.9 | 7.7 | 4.4 | 6.8 | 7.0 | 7.9 | 6.2 | 7.6 | 7.9 |
| l/d-Lys3-HN | 8.8 | 3.1 | 2.4 | 2.1 | 1.3 | 2.8 | 1.4 | 2.0 | 1.6 |
| l/d-Phe4-HN | 6.6 | 7.2 | 5.2 | 5.3 | 10.0 | 8.0 | 6.3 | 8.8 | 9.2 |
| l-Glu6-HN | 1.7 | 2.3 | –1.0 | 1.2 | 1.2 | 1.2 | 1.8 | 1.5 | 7.2 |
| l/d-Ala7-HN | 3.0 | 7.6 | 0.3 | 1.4 | 9.6 | 6.2 | 9.9 | 9.0 | 8.3 |
| l/d-Lys3-HNε | 6.6 | 7.3 | n.d. | 4.3 | 6.6 | 6.6 | n.d. | 6.5 | 2.0 |
aCoefficients in –Δδ/ΔT (ppb K–1). Fully H-bonded protons (boldface) have –Δδ/ΔT < 4.0 ppb K–1 and partially H-bonded protons have –Δδ/ΔT = 4.0–7.0 ppb K–1. n.d. = not determined. Low values indicating intramolecular H-bonds are highlighted in bold.
bCoefficient values given for the major conformer of the prolyl bond, trans for 3 and cis for 7. Residue number according to the position in the parent linear precursor (Table 1).