Compounds of formula I, wherein R1, R2, R3, X1, X2and Ar, are as defined herein or pharmaceutically acceptable salts thereof, inhibit HIV-1 reverse transcriptase and afford a method for prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC. The present invention also relates to compositions containing compounds of formula I useful for the prevention and treatment of HIV-1 infections and the treatment of AIDS and/or ARC.本發明提供式I化合物(其中R1、R2、R3、X1、X2及Ar如本文中所定義)或其醫藥學上可接受之鹽，其抑制HIV-1逆轉錄酶且提供用於預防及治療HIV-1感染及治療AIDS及/或ARC之方法。本發明亦係關於含有適用於預防及治療HIV-1感染及治療AIDS及/或ARC之式I化合物之組合物。
