PyBOP® and PyBroP: Two reagents for the difficult coupling of the α,α-dialkyl amino acid, Aib.
摘要:
The difficult coupling of alpha-aminoisobutyric acid (Aib) was carried out using PyBOP(R) and PyBroP in a comparative study with BOP and BroP. These reagents gave good results under simple conditions (one pot, r.t., 1 h). Coded amino acids could be coupled with Aib using PyBOP under standard conditions of peptide synthesis without racemization whereas the coupling of two Aib residues required PyBroP/DMAP. A fragment containing an Aib C-terminal could be coupled without epimerization of the penultimate residue.
In view of developing alternatives to classical peptidesynthesis strategies that suffer from low efficacy and negative environmental impact, the reactivity of N-protected α-amino acids, amino esters, and N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide was studied under liquid-assisted grinding (LAG) conditions. The optimal reaction conditions enabled the intensive and environmentally benign mechanosynthesis