Optimization of P1 residue of new candidates for the SARS-CoV-2 M^pro α-ketoamide inhibitors^a.

Compound	Formula: P3–P2–P1–P1′	ΔΔEint,MMa [kcal mol−1]	M w b [g mol−1]
C1		6.6	506.6
11n		7.6	532.6
C2		3.5	530.6
C3		5.2	530.6
C4		1.3	547.6

^{a a,b}See the footnote of Table 1.