A classical peptide coupling approach for the total synthesis of simnotrelvir

The total synthesis of an oral small-molecule antiviral agent; a structure based developmental drug simnotrelvir has been accomplished. The synthesis involves readily accessible commercial amino acids L-tert-leucine, 4-hydroxy-l-proline and l-glutamic acid that are easily converted to the key intermediates and are coupled together following classical peptide coupling technique using HATU and NMM. One of the crucial step in the synthesis involved a one pot Boc-deprotection and trifluoroacetylation of tert-leucine amino acid moiety mediated by ZnCl₂.