Table 2. Comparison of the Yield and Racemization of Z-Gly-Phe-Val-OMe Synthesized Using Various Coupling Reagents.
| entry | coupling reagent | yield (%) | racemization (%) |
|---|---|---|---|
| 1 | HDMB | 90 | 2.9 |
| 2 | HDMA | 90 | 0.7 |
| 3 | HBTU | 89 | 5.9 |
| 4 | HATU | 90 | 1.6 |
| 5 | TCBOXY | 90 | n.d.a |
No racemization could be detected.