Nonnucleoside reverse transcriptase inhibitors

A method for treating an HIV infection, or preventing an HIV infection, or treating AIDS or ARC, comprising administering to a host in need thereof a therapeutically effective amount of a compound of formula I

• wherein:
• X1 is selected from the group consisting of R5O, R5S(O)n, R5CH2, R5CH2O, R5CH2S(O)n, R5OCH2, R5S(O)n, CH2 and NR5R6;
• X2 is selected from the group consisting of O, S, and NR7;
• R1 and R2 are
• (i) each independently selected from the group consisting of hydrogen, C1-6 alkyl, C1-6 haloalkyl, C3-8 cycloalkyl, C1-6 alkylthio, C1-6 alkylsulfinyl, C1-6 alkylsulfonyl, C1-6 haloalkoxy, C1-6 haloalkylthio, halogen, amino, alkylamino, dialkylamino, aminoacyl, nitro and cyano;
• or,
• (ii) taken together are —CH═CH—CH═CH—, or
• (iii) taken together along with the carbons to which they are attached to form a five- or six-membered heteroaromatic or heterocyclic ring with a one or two heteroatoms independently selected from the group consisting of O, S and NH;
• R3 and R4 are each independently selected from the group consisting of hydrogen, C1-6 alkyl, C1-6 haloalkyl, C3-8 cycloalkyl, C1-6 alkoxy, C1-6 alkylthio, C1-6 haloalkoxy, C1-6 haloalkyl halogen, amino, alkylamino, dialkylamino, aminoacyl, nitro and cyano;
• R5 is selected from the group consisting of phenyl, naphthyl, pyrdinyl, pyridinyl N-oxide, indolyl, indolyl N-oxide, quinolinyl, quinolinyl N-oxide,, pyrimidinyl, pyrazinyl and pyrrolyl;
• wherein, said phenyl, said naphthyl, said pyrdinyl, said pyridinyl N-oxide, said indolyl, said indolyl N-oxide, said quinolinyl, said quinolinyl N-oxide,, said pyrimidinyl, said pyrazinyl and said pyrrolyl groups are optionally substituted with one to three substituents independently selected from the group consisting of hydrogen, C1-6 alkyl, C1-6 haloalkyl, C3-8 cycloalkyl, C1-6 alkoxy, C1-6 alkylthio, C1-6 alkylsulfinyl, C1-6 alkylsulfonyl, C1-6 haloalkoxy, C1-6 haloalkylthio, halogen, amino, alkylamino, dialkylamino, aminoacyl, acyl, alkoxycarbonyl, carbamoyl, N-alkylcarbamoyl, N,N-dialkylcarbamoyl, nitro and cyano;
• R6 is hydrogen, C1-6 alkyl, or acyl;
• R7 is hydrogen or C1-6 alkyl optionally substituted with one or two substituents independently selected from the group consisting of hydroxy, alkoxy, thiol, alkylthio, C1-6 alkylsulfinyl, C1-6 alkylsulfonyl, halogen, amino, alkylamino, dialkylamino, aminoalkyl, alkylaminoalkyl, and dialkylamino;
• n is an integer from 0 to 2;
• or, acid addition salts thereof.