Table 2. Relationships between the diastereoselective complementary duplex formations and downfield chemical shifts (Δδ) of the linker amide NH resonances of the amidine strands of 3b·1a–4b·2a duplexes from the monomeric amidine strands (3b and 4b).
| Entry | Combination | Duplex | ΔdNH (p.p.m.) | d.e. (%) | Supplementary Fig no. |
|---|---|---|---|---|---|
| 1 | (R,R,S,S,R,R)-3b (CONH-cHex) and 1a (NHCO-cHex) | 3b·(R,R)-1afavoured | 0.56 | 64 ((R,R)-1a-rich) | 64 |
| 3b·(S,S)-1adisfavoured | 0.03 | ||||
| 2 | (R,R,S,S,R,R)-3b (CONH-cHex) and 2a (CONH-cHex) | 3b·(R,R)-2adisfavoured | 0.12 or 0.09* | >99 ((S,S)-2a-rich) | 62 |
| 3b·(S,S)-2afavoured | 0.73 or 0.53* | ||||
| 3 | (R,R,S,S,R,R)-4b (NHCO-cHex) and 1a (NHCO-cHex) | 4b·(R,R)-1adisfavoured | 0.52 | 74 ((S,S)-1a-rich) | 67 |
| 4b·(S,S)-1afavoured | 1.16 or 1.08* | ||||
| 4 | (R,R,S,S,R,R)-4b (NHCO-cHex) and 2a (CONH-cHex) | 4b·(R,R)-2afavoured | 0.90 | 34 ((R,R)-2a-rich) | 66 |
| 4b·(S,S)-2adisfavoured | 0.59 |
cHex, (R,R)-trans-1,2-cyclohexane.
*The amide NH resonances of the amidine strands of duplexes could not be distinguished from those of the carboxylic acid strands because of overlapping with the phenyl and aliphatic proton signals. For the assignments of the amide NH proton signals, see Supplementary Figs 62–67.