(S)-6-Bromo-4-(cyclopropylethynyl)-4-(trifluoromethyl)-1H-benzo[d][1,3]ozazin-2(4H)-one is a reagent used for research purposes. (S)-6-Bromo-4-(cyclopropylethynyl)-4-(trifluoromethyl)-1H-benzo[d][1,3]oxazin-2(4H)-one is a bromide derivative of Deschloro-(S)-efavirenz (D226525 CAS: 445468-46-2).