To improve the solubility characteristics of inhibitors incorporating the lipophilic 2,6-dichlorobenzoate, a limited set of inhibitors containing smaller or more polar amine capping fragments were prepared (Table 2). Replacement of the 4-methoxy indole cap present in 22 with a benzimidazole provided 31. This inhibitor displayed potent irreversible inhibition kinetics but did not improve solubility compared to 22. Reduction in the size of the P2 capping element as represented by 29 and 30 provided derivatives that possessed weak reversible SARS CoV-1 3CLpro inhibition.