116140-00-2Relevant academic research and scientific papers
PyBOP and PyBroP: Two reagents for the difficult coupling of the α,α-dialkyl amino acid, Aib
Frerot, Eric,Coste, Jacques,Pantaloni, Antoine,Dufour, Marie-Noelle,Jouin, Patrick
, p. 259 - 270 (2007/10/02)
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.
The Azirine/Oxazolone Method in Peptide Chemistry: Synthesis of Tripeptide Models
Wipf, Peter,Heimgartner, Heinz
, p. 140 - 154 (2007/10/02)
Tripeptides 5, containing an α,α-disubstituted α-amino acid and ethyl p-aminobenzoate, were synthesized in high yield by application of the azirine/oxazolone method (Table 2).In this versatile approach for the incorporation of disubstituted residues into the peptide chain, N-protected peptides or amino acids are coupled with 2,2-dialkyl-3-amino-2H-azirines and, after the selective hydrolysis of the newly formed C-terminal amid bond, further condensed with amino components via in situ generated oxazole-5(4H)-ones in the presence of additives (Scheme 1).A comparison with conventional procedures clearly demonstrates the advantages of this new method that works equally well with β-branched, cyclic, or acyclic disubstituted amino acids.
