Table 1.

Structures and activity of 3-chloropyridinyl ester-derived SARS-CoV-2 3CLpro inhibitors.

Entry	Entry Compound Structure	SARS CoV-2 3CLpro IC50 (μM)	SARS-CoV-2 EC50 (μM)a
1		0.25	2.8
2		0.32	15
3		0.31	43.7
4		0.12	69.8
5		0.90	8.1
6		0.073	15
7		0.38	11.5
8		0.47	56.7
9		10.3	>100
10		0.59	3.1
11		0.87	14
12		0.34	>100
13		0.49	57.1
14		1.19	>100
15		0.42	>100

^aCompounds 3 and 4 exhibited antiviral EC₅₀ values 3.4 μM and 3.2 μM, respectively.