A compound of formula I: wherein: R 1 is selected from the group consisting of (C 3 -C 7)carbomonocyclyl, (C 1 -C 6)alkyl, carboxy, (C 9 -C 11)carbobicyclyl, heteromonocyclyl, and heterobicyclyl, wherein said (C 3 -C 7)carbomonocyclyl, (C 1 -C 6)alkyl, (C 9 -C 11)carbobicyclyl, heteromonocyclyl, and heterobicyclyl may be optionally substituted with from one to three substituents selected independently from the group consisting of halogen, cyano, hydroxy, nitro, amino, acetoxy, carboxy, (C 1 -C 7)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 3)alkoxy, halo(C 1 -C 3)alkoxy, (C 1 -C 6)acyl, (C 1 -C 3)alkoxy(C 1 -C 3)alkyl, hydroxy(C 1 -C 3)alkyl, heteroaryl, benzenesulfonyl, (C 1 -C 3)alkoxycarbonyl, aminocarbonyl, (1 l -C 3)alkylaminocarbonyl, di(C 1 -C 3)alkylaminocarbonyl, (C 1 -C 3)alkylamino, di(C 1 -C 3)alkylamino, amino(C 1 -C 3)alkyl, (C 1 -C 3)alkylamino(C 1 -C 3)alkyl (C 1 -C 3)dialkylamino(C 1 -C 3)alkyl, (C 1 -C 3)alkylthio, (C 1 -C 3)alkylsulfonylamino, (C 1 -C 3)alkylsulfinyl, (C 1 -C 3)alkylsulfonyl, phenoxy, and benzyloxy; R 2 is selected from the group consisting of hydroxy(C 1 -C 3)alkyl, hydrogen, (C 1 -C 7)hydrocarbyl, halogen, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, -C(=O)O(C 1 -C 6)alkyl, -C(=O)NR 20 R 21, and (C 1 -C 6)oxaalkyl; R 3 is selected from the group consisting of hydrogen, halogen, (C 1 -C 6)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, and (C 1 -C 3)alkoxy; R 4 is selected from the group consisting of hydrogen, halogen, (C 1 -C 6)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, and (C 1 -C 3)alkoxy; R 10 is selected independently in each instance from the group consisting of hydrogen and methyl; R 20 is selected from the group consisting of hydrogen and (C 1 -C 6)hydrocarbyl; R 21 is selected from the group consisting of hydrogen, (C 1 -C 6)hydrocarbyl, (C 1 -C 6)oxaalkyl, amino(C 1 -C 6)alkyl, (C 1 -C 3)alkylamino(C 1 -C 6)alkyl, di(C 1 -C 3)alkylamino(C 1 -C 6)alkyl, and -(CH 2) m -Het, wherein Het is an aliphatic mono- or bicyclic heterocycle, optionally substituted with a substituent selected from the group consisting hydroxy, amino, acetoxy, carboxy, (C 1 -C 7)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 3)alkoxy, halo(C 1 -C 3)alkoxy, (C 1 -C 6)acyl, (C 1 -C 3)alkoxy(C 1 -C 3)alkyl, hydroxy(C 1 -C 3)alkyl, aminocarbonyl, (C 1 -C 3)alkylaminocarbonyl, di(C 1 -C 3)alkylaminocarbonyl, (C 1 -C 3)alkylamino, and di(C 1 -C 3)alkylamino; or, taken together with the nitrogen to which they are attached, R 20 and R 21 form an aliphatic heterocyle; n is one, zeroor two; m is zero, one or two; and X is S; or, when n is 1 and R 1 is optionally substituted phenyl, X is S or O; with the proviso that, when R 1 is phenyl, X is sulfur, and n is one, at least one of R 2, R 3, R 4, and R 10 is other than hydrogen. R 1 is selected from the group consisting of (C 3 -C 7)carbomonocyclyl, (C 1 -C 6)alkyl, carboxy, (C 9 -C 11)carbobicyclyl, heteromonocyclyl, and heterobicyclyl, wherein said (C 3 -C 7)carbomonocyclyl, (C 1 -C 6)alkyl, (C 9 -C 11)carbobicyclyl, heteromonocyclyl, and heterobicyclyl may be optionally substituted with from one to three substituents selected independently from the group consisting of halogen, cyano, hydroxy, nitro, amino, acetoxy, carboxy, (C 1 -C 7)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 3)alkoxy, halo(C 1 -C 3)alkoxy, (C 1 -C 6)acyl, (C 1 -C 3)alkoxy(C 1 -C 3)alkyl, hydroxy(C 1 -C 3)alkyl, heteroaryl, benzenesulfonyl, (C 1 -C 3)alkoxycarbonyl, aminocarbonyl, (1 l -C 3)alkylaminocarbonyl, di(C 1 -C 3)alkylaminocarbonyl, (C 1 -C 3)alkylamino, di(C 1 -C 3)alkylamino, amino(C 1 -C 3)alkyl, (C 1 -C 3)alkylamino(C 1 -C 3)alkyl (C 1 -C 3)dialkylamino(C 1 -C 3)alkyl, (C 1 -C 3)alkylthio, (C 1 -C 3)alkylsulfonylamino, (C 1 -C 3)alkylsulfinyl, (C 1 -C 3)alkylsulfonyl, phenoxy, and benzyloxy; R 2 is selected from the group consisting of hydroxy(C 1 -C 3)alkyl, hydrogen, (C 1 -C 7)hydrocarbyl, halogen, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, -C(=O)O(C 1 -C 6)alkyl, -C(=O)NR 20 R 21, and (C 1 -C 6)oxaalkyl; R 3 is selected from the group consisting of hydrogen, halogen, (C 1 -C 6)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, and (C 1 -C 3)alkoxy; R 4 is selected from the group consisting of hydrogen, halogen, (C 1 -C 6)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 6)acyl, and (C 1 -C 3)alkoxy; R 10 is selected independently in each instance from the group consisting of hydrogen and methyl; R 20 is selected from the group consisting of hydrogen and (C 1 -C 6)hydrocarbyl; R 21 is selected from the group consisting of hydrogen, (C 1 -C 6)hydrocarbyl, (C 1 -C 6)oxaalkyl, amino(C 1 -C 6)alkyl, (C 1 -C 3)alkylamino(C 1 -C 6)alkyl, di(C 1 -C 3)alkylamino(C 1 -C 6)alkyl, and -(CH 2) m -Het, wherein Het is an aliphatic mono- or bicyclic heterocycle, optionally substituted with a substituent selected from the group consisting hydroxy, amino, acetoxy, carboxy, (C 1 -C 7)hydrocarbyl, halo(C 1 -C 6)alkyl, (C 1 -C 3)alkoxy, halo(C 1 -C 3)alkoxy, (C 1 -C 6)acyl, (C 1 -C 3)alkoxy(C 1 -C 3)alkyl, hydroxy(C 1 -C 3)alkyl, aminocarbonyl, (C 1 -C 3)alkylaminocarbonyl, di(C 1 -C 3)alkylaminocarbonyl, (C 1 -C 3)alkylamino, and di(C 1 -C 3)alkylamino; or, taken together with the nitrogen to which they are attached, R 20 and R 21 form an aliphatic heterocyle; n is one, zeroor two; m is zero, one or two; and X is S; or, when n is 1 and R 1 is optionally substituted phenyl, X is S or O; with the proviso that, when R 1 is phenyl, X is sulfur, and n is one, at least one of R 2, R 3, R 4, and R 10 is other than hydrogen.