Backbone-Fluorinated 1,2,3-Triazole-Containing Dipeptide Surrogates

The 1,2,3-triazole moiety can be incorporated as a peptide bond bioisostere to provide protease resistance in peptidomimetics. Herein, we report the synthesis of peptidomimetic building blocks containing backbone-fluorinated 1,4-disubstituted 1,2,3-triazole moieties. Synthetic protocols for the preparation of various Xaa-Gly dipeptide surrogates in the form of Xaa-ψ[triazole]-F2Gly building blocks were established, and selected examples were introduced into the endogenous peptide opioid receptor ligand Leu-enkephalin as a model compound.