PyBOP and PyBroP: Two reagents for the difficult coupling of the α,α-dialkyl amino acid, Aib

Article abstract of DOI:10.1016/S0040-4020(01)80922-4

The difficult coupling of α-aminoisobutyric acid (Aib) was carried out using PyBOP and PyBroP in a comparative study with BOP and BroP. These reagents gave good results under simple conditions (one pot, r.t., 1h). 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.