Fmoc-Glu(OtBu)-OH (CAS 71989-18-9), also known as Nα-Fmoc-L-glutamic acid γ-tert-butyl ester, is the standard doubly protected L-glutamic acid for Fmoc-SPPS. It belongs to the Fmoc-glutamate tBu ester class. The tBu ester protects the γ-carboxyl group, which stops side chain activation and unwanted branching during peptide synthesis. Fmoc-Glu(OtBu)-OH is found in many peptides, including GLP-1 analogues (Liraglutide, Semaglutide), teriparatide, and many growth factors. It is also used as a building block for the fatty acid linker in GLP-1 receptor agonists. Aspartimide/glutarimide (cyclization artifact) is a major side reaction, especially in sequences with Glu(OtBu)-Gly or something like it. Pseudo-proline dipeptide building blocks help cut down on this. Another possible side reaction is the dehydration of glutamate to make glutamic anhydride.
ApiSyn sells Fmoc-Glu(OtBu)-OH (CAS 71989-18-9) as a pharmaceutical-grade Fmoc amino acid building block and reference standard for GMP peptide SPPS and quality control.
| Chemical Name | (S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid |
| Molecular Formula | C24H27NO6 |
| Molecular Weight | 425.5 |
| CAS Number | 71989-18-9 |