Efavirenz (SUSTIVA) is a potent non-nucleoside reverse transcriptase inhibitor. Due to the observation of breakthrough mutations of the reverse transcriptase enzyme during Efavirenz therapy, we sought to develop an optimized second generation series. To that end, SAR of the substituents on the aromatic ring was undertaken and the results are summarized here. The 5,6-difluoro (4f) and the 6-methoxy (4m) substituted benzoxazinones were determined to be equipotent, and as a result such substitution patterns will be incorporated in second generation scaffolds.