Fmoc-Thr(tBu)-OH (CAS 71989-35-0), also known as Nα-Fmoc-O-tert-butyl-L-threonine, is the standard doubly protected threonine for Fmoc-SPPS in the Fmoc-threonine tBu ether class. During SPPS, the tBu ether protects the threonine β-hydroxyl. After TFA deprotection, the free OH is restored in the final product. Threonine has two stereocenters (2S,3R in L-Thr). Epimerization at Cβ to make L-allo-threonine (2S,3S) is a quality issue that can be found by chiral HPLC and amino acid analysis.
There are important threonine residues in GLP-1 analogues (Thr11, Thr13, Thr16 in semaglutide), Teriparatide, GnRH, Octreotide (Thr5 in the active octapeptide), and Desmopressin. In Fmoc-SPPS, Thr(tBu) coupling is effective, but it is necessary to regulate β-elimination and the formation of O-acyl isourea.
ApiSyn offers Fmoc-Thr(tBu)-OH (CAS 71989-35-0) as a pharmaceutical-grade Fmoc amino acid and a key raw material reference standard for GMP peptide manufacturing and controlling diastereomeric purity.
| Chemical Name | N-(((9H-Fluoren-9-yl)methoxy)carbonyl)-O-(tert-butyl)-L-threonine |
| Molecular Formula | C23H27NO5 |
| Molecular Weight | 397.5 |
| CAS Number | 71989-35-0 |