has role efavirenz 1,4-Dihydro-2<em>H</em>-3,1-benzoxazin-2-one substituted at the 4 position by cyclopropylethynyl and trifluoromethyl groups (<i>S</i> configuration) and at the 6 position by chlorine. A non-nucleoside reverse transcriptase inhibitor with activity against HIV, it is used with other antiretrovirals for combination therapy of HIV infection. antiviral drug organochlorine compound organofluorine compound benzoxazine cyclopropanes HIV-1 reverse transcriptase inhibitor acetylenic compound