Table 1.
Yields and conditions for Scheme 3: Abbreviations: p: the cleaved mixture was triturated and washed with petroleum ether 40–60 °C before yield and impurity calculation; n.o.: not observed; a: the loading was possibly inhomogeneous, and might have been washed with an insufficient amount of piperidine in DMF.
| Abbreviation | Loading Ratio (Fmoc-1-aminoethyltetrazole 10: resin) | Theoretical Yield of 13 (%) p | Percentage of Fmoc Residue in 13% | Yield of 14 (%) | |
|---|---|---|---|---|---|
| 14g-L | Gly-L-Ala(T) | 1:1 | 59 | n.o. | 99 |
| 14a-LL | L-Ala-L-Ala(T) | 1:1 | 58 | 5 | 86 |
| 14a-LD | L-Ala-D-Ala(T) | 1:1 | 89 | <1 | 58 |
| 14d-LL | β-Ala-L-Ala(T) | 1:1 | 67 | 2 | 78 |
| 14e-LL | L-Nor-L-Ala(T) | 1:1 | 51 | 14a | 77 |
| 14h-LL | L-Leu-L-Ala(T) | 2:1 | 84 | 6 | 81 |
| 14h-LD | L-Leu-D-Ala(T) | 1:1 | 69 | <1 | 53 |
| 14i-LL | L-Ile-L-Ala(T) | 1:1 | 62 | 2 | 86 |
| 14f-LL | L-Pyr-L-Ala(T) | 2:1 | 89 | 12 | 84 |
| 14j-LL | L-Phe-L-Ala(T) | 1:1 | 79 | 15a | 20 |
| 14b-LL | L-Ala-L-EtGly(T) | 1:1 | 52 | 3 | 86 |