Phenylpropenamide derivatives: anti-hepatitis B virus activity of the Z isomer, SAR and the search for novel analogs

Phenylpropenamides have been reported to be a class of non-nucleoside inhibitors of the hepatitis B virus (HBV). This class of compounds was explored with the objective of developing potent anti-HBV agents, with a novel mechanism of action, that could be combined with nucleos(t)ide analogs currently used to treat HBV infection. To accomplish this objective a series of substituted arylpropenamide derivatives were prepared and the E and Z geometrical isomers were separated. The structural identity of each of the E and Z isomers was determined by single crystal X-ray crystallography. Contrary to previous reports, the activity of this class of molecules resides in the Z isomer. Further structure-activity relationship studies around the active Z isomer identified compounds that displayed potent antiviral activity against HBV with EC₉₀ value of approximately 0.5 μM in vitro. Attempts to develop ring constrained analogs did not lead to active HBV inhibitors.