Table 1  SARS CoV-1 3CLpro Inhibition Data for Acyloxymethylketone Inhibitors
      SARS CoV-1 3CLpro FRETa
entry  R  kobs/I (M–1 s–1)  IC50 (nM)
12     283,039 ± 22,586   
13  Me     220 ± 0.5
14  cyc-propyl     182 ± 6
15  tert-butyl     230 ± 5
16  Ph     86 ± 3
17  4-OMe-Ph     79 ± 3
18  4-Me-Ph     87 ± 2
19  4-CN-Ph     53 ± 1
20  4-F-Ph     82 ± 3
21  4-Cl-Ph     97 ± 3
22  2,6-(Cl)2-Ph  62,993 ± 2,501   
23  2,6-(F)2-Ph  12,776 ± 594   
24  2-OH-4-Cl-Ph  11,525 ± 40   
25  2-F, 4-CN-Ph  13,321 ± 2,309   
26  2,6-(Me)2-Ph     74 ± 4
27  2,6-(MeO)2-Ph     205 ± 2
28  2-CN-Ph     17 ± 2
a  See the Experimental Section for details on assay methods; the values were calculated from at least eight data points with at least two independent determinations.