A compound represented by structural formula I: or a pharmaceutically acceptable salt thereof, wherein: X represents ZC 6-10 aryl, said aryl optionally substituted with 1 to 3 groups of R a; Z represents a bond, - n -, -(C NH-, -CH -, -C(CH 3)OH-, -(CH 2) n NH-, or-(CH 2) n NCH 3 -; R 1 represents C 1-6 alkyl, (CH 2) 1-4 OR or C 1-4 haloalkyl, wherein said alkyl is optionally substituted with 1 to 3 groups of R a; R 2 represents halo, C 1-6 alkyl, (CH 2) n OR, C 1-4 haloalkyl, C OR, C=O, (CH 2) n C 3-10 heterocyclyl, O-(CH 2) n C 4-10 heterocyclyl, C NH(CH 2 CF 3), NR 2, NHSO 2 R, C R, C -N-linked morpholinyl, NHC CH 3, (CH 2) n C(CF 3)OH, CF 2 CH 2 OH, said alkyl and heterocyclyl optionally substituted with 1 to 3 groups of R a, R 3 and R 3a independently represent hydrogen, C 1-6 alkyl, or C 3-6 cycloalkyl, or R 3 and R 3a can combine with the carbon atom to which they are attached to form a C 3-6 cycloalkyl, or C 4-10 heterocycloalkyl, said alkyl, cycloalkyl, and heterocycloalkyl optionally substituted with 1 to 3 groups of R a, or R 3 or R 3a can combine with X and the carbon atom to which they are attached to form a C 6-10 aryl, said aryl optionally substituted with 1 to 3 groups of R a, R represents hydrogen or C 1-6 alkyl, said alkyl optionally substituted with 1 to 3 groups of R a, R a is selected from the group consisting of halo, CN, C 1-6 alkyl, (CH 2) n OR, (CH 2) n C 1-4 haloalkyl, O-C 1-4 haloalkyl, SCF 3, SF 5, C 6-10 aryl, C N(CH 3) 2, =NOH, NHOH, SO 2 R, NR 2, OC CH 3, NHC CH 3, OCH 2 C 6-10 aryl, and C 3-6 cycloalkyl, said cycloalkyl optionally substituted with 1 to 3 groups selected from C 1-6 alkyl and C 1-4 haloalkyl; n represents 0, 1, 2, 3, or 4. X represents ZC 6-10 aryl, said aryl optionally substituted with 1 to 3 groups of R a; Z represents a bond, - n -, -(C NH-, -CH -, -C(CH 3)OH-, -(CH 2) n NH-, or-(CH 2) n NCH 3 -; R 1 represents C 1-6 alkyl, (CH 2) 1-4 OR or C 1-4 haloalkyl, wherein said alkyl is optionally substituted with 1 to 3 groups of R a; R 2 represents halo, C 1-6 alkyl, (CH 2) n OR, C 1-4 haloalkyl, C OR, C=O, (CH 2) n C 3-10 heterocyclyl, O-(CH 2) n C 4-10 heterocyclyl, C NH(CH 2 CF 3), NR 2, NHSO 2 R, C R, C -N-linked morpholinyl, NHC CH 3, (CH 2) n C(CF 3)OH, CF 2 CH 2 OH, said alkyl and heterocyclyl optionally substituted with 1 to 3 groups of R a, R 3 and R 3a independently represent hydrogen, C 1-6 alkyl, or C 3-6 cycloalkyl, or R 3 and R 3a can combine with the carbon atom to which they are attached to form a C 3-6 cycloalkyl, or C 4-10 heterocycloalkyl, said alkyl, cycloalkyl, and heterocycloalkyl optionally substituted with 1 to 3 groups of R a, or R 3 or R 3a can combine with X and the carbon atom to which they are attached to form a C 6-10 aryl, said aryl optionally substituted with 1 to 3 groups of R a, R represents hydrogen or C 1-6 alkyl, said alkyl optionally substituted with 1 to 3 groups of R a, R a is selected from the group consisting of halo, CN, C 1-6 alkyl, (CH 2) n OR, (CH 2) n C 1-4 haloalkyl, O-C 1-4 haloalkyl, SCF 3, SF 5, C 6-10 aryl, C N(CH 3) 2, =NOH, NHOH, SO 2 R, NR 2, OC CH 3, NHC CH 3, OCH 2 C 6-10 aryl, and C 3-6 cycloalkyl, said cycloalkyl optionally substituted with 1 to 3 groups selected from C 1-6 alkyl and C 1-4 haloalkyl; n represents 0, 1, 2, 3, or 4.