L-Glutamic acid alpha-tert-butyl ester (CAS 45120-30-7), also known as H-Glu(α-OtBu)-OH or L-Glu alpha-mono-tBu ester, is a selectively protected L-glutamic acid derivative. In this case, the alpha-carboxyl is protected as a tBu ester and the gamma-carboxyl is free. It belongs to the mono-protected glutamic acid class of amino acids. This chemical is an important part of making peptides in solution and putting together fatty acid-amino acid linker parts for GLP-1 receptor agonist side chains (Liraglutide, Semaglutide).
During the synthesis of GLP-1 fatty acid linkers, the free gamma-COOH forms an amide bond with the ε-NH2 of a protected lysine residue. Then, TFA cleaves the alpha-OtBu group to reveal the free α-carboxyl, which can be used for palmitoyl or fatty diacid acylation. This selective protection strategy lets us control exactly which way the glutamic acid goes in the side chain linker.
ApiSyn sells L-Glutamic acid alpha-tert-butyl ester (CAS 45120-30-7) as a pharmaceutical-grade building block for making peptide APIs and linking fatty acids to GLP-1.
| Chemical Name | (S)-4-Amino-5-(tert-butoxy)-5-oxopentanoic acid |
| Molecular Formula | C9H17NO4 |
| Molecular Weight | 203.2 |
| CAS Number | 45120-30-7 |