Table 2.

Antiviral activity of compound 1 analogs modified at the thiophenyl ring^a

compd	R4	R6	R3’	R4’	IC50
18	H	Me	H	H	NA
18a	H	Me	Cl	H	51
18b	H	Me	F	H	69
18c	H	Me	H	Br	NA
18d	H	Me	H	Me	NA
18e	H	Me	H	OMe	NA
18f	H	Me	H	CO2H	NA
18g	H	Me	H	CF3	33
19	Me	H	H	OMe	NA
19a	Me	H	H	Me	NA
19b	Me	H	H	CO2Me	NA
19c	Me	H	H	NO2	NA

^aIC₅₀ values were determined from triplicate measurements and repeated at least twice. Values ≥ 100 µM were designated as not active (NA).