We have recently shown that the addition of a methyl sulfonamide group to the 7-position of the D-ring of the benzothiadiazine core (compound 1, IC 50 = 2.4 nM) dramatically improved the potency of the series. 7 In an effort to further probe the thiadiazine binding site and possibly obtain even greater potency against the RdRp, we sought to extend more functionality away from the methyl sulfonamide. An attractive strategy for accomplishing this endeavor was to ...