Synthesis of glutamic acid and glutamine peptides possessing a trifluoromethyl ketone group as SARS-CoV 3CL protease inhibitors

Trifluoromethyl-β-amino alcohol 11 [(4S)-tert-butyl 4-amino-6,6,6-trifluoro-5-hydroxyhexanoate] was synthesized in five steps starting from Cbz-l-Glu-OH 5 where the key step involved the introduction of the trifluoromethyl (CF(3)) group to oxazolidinone 7, resulting in the formation of silyl ether 8 [(4S,5S)-benzyl 4-(2-(tert-butoxycarbonyl)ethyl)-5-(trifluoromethyl)-5-(trimethylsilyloxy)oxazolidine-3-carboxylate]. Compound 11 was then converted into four tri- and tetra-glutamic acid and glutamine peptides (1-4) possessing a CF(3)-ketone group that exhibited inhibitory activity against severe acute respiratory syndrome coronavirus protease (SARS-CoV 3CL(pro)).