A compound of structural formula I: or pharmaceutically acceptable salts and individual enantiomers and diastereomers thereof wherein: W and Z independently are absent or represent C(R 2 ) 2 , -O-, NR 2 , CO, or SO 0-2 ; R 2 represents H, C 1-6 alkyl, CF 3 , OH, CHF 2 , or CH 2 F; R 3 is CHR 4 R 5 wherein one of R 4 and R 5 is C 1-6 alkyl or hydrogen and the other is (CH 2 ) n phenyl, (CH 2 ) n pyridyl, (CH 2 ) n pyrimidyl, (CH 2 ) n triazolyl, pyrazinyl or (CH 2 ) n oxadiazolyl, said phenyl, pyridyl, pyrimidyl, triazolyl, pyrazinyl or oxadiazolyl optionally substituted with 1 to 3 groups of R a ; R 6 represents hydrogen, OR 2 , CF 3 , C(R 2 ) 2 OR 2 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, said alkyl being optionally substituted with 1 to 3 groups of R a' ; R 7 is represented by structural formula Ia: wherein X is N or CH; and R 1 represents H, C 1-6 alkyl, halogen, (CH 2 ) n CF 3 , C 3-10 cycloalkyl, C(R 2 ) 2 OH, -O-, CN, (CH 2 ) n OR 2 , (CH 2 ) n C 5-10 heterocyclyl, (CH 2 ) n C 6-10 aryl, or C 1-6 alkoxy; said alkyl, cycloalkyl, heterocyclyl and aryl optionally substituted with 1 to 3 groups of C 1-6 alkyl, halogen, hydroxyl, (CH 2 ) n CF 3 , or CN; R a represents C 1-6 alkyl, halogen, hydroxyl, OR 2 (CH 2 ) n CF 3 , C 3-6 cycloalkyl, NR 2 C(O)R 2 , C(O)N(R 2 ) 2 , C(R 2 ) 2 OR 2 , C(O)R 2 , NO 2 , CN, N(R 2 ) 2 , C(O)OR 2 , SO 2 R 2 , OR 2 , (CH 2 ) n C 5-10 heterocyclyl, or (CH 2 ) n C 6-10 aryl, said heterocyclyl and aryl optionally substituted with 1 to 3 groups of C 1-6 alkyl, halogen, hydroxyl, (CH 2 ) n CF 3 ,or CN; R a' is C 1-6 alkyl, halogen, hydroxyl, OR 2 (CH 2 ) n CF 3 , NR 2 C(O)R 2 , C(O)N(R 2 ) 2 , C(R 2 ) 2 OR 2 , C(O)R 2 , NO 2 , CN, N(R 2 ) 2 , C(O)OR 2 , SO 2 R 2 , or OR 2 ; and n represents 0 to 4, provided that WZR 6 is not hydrogen. W and Z independently are absent or represent C(R 2 ) 2 , -O-, NR 2 , CO, or SO 0-2 ; R 2 represents H, C 1-6 alkyl, CF 3 , OH, CHF 2 , or CH 2 F; R 3 is CHR 4 R 5 wherein one of R 4 and R 5 is C 1-6 alkyl or hydrogen and the other is (CH 2 ) n phenyl, (CH 2 ) n pyridyl, (CH 2 ) n pyrimidyl, (CH 2 ) n triazolyl, pyrazinyl or (CH 2 ) n oxadiazolyl, said phenyl, pyridyl, pyrimidyl, triazolyl, pyrazinyl or oxadiazolyl optionally substituted with 1 to 3 groups of R a ; R 6 represents hydrogen, OR 2 , CF 3 , C(R 2 ) 2 OR 2 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, said alkyl being optionally substituted with 1 to 3 groups of R a' ; R 7 is represented by structural formula Ia: wherein X is N or CH; and R 1 represents H, C 1-6 alkyl, halogen, (CH 2 ) n CF 3 , C 3-10 cycloalkyl, C(R 2 ) 2 OH, -O-, CN, (CH 2 ) n OR 2 , (CH 2 ) n C 5-10 heterocyclyl, (CH 2 ) n C 6-10 aryl, or C 1-6 alkoxy; said alkyl, cycloalkyl, heterocyclyl and aryl optionally substituted with 1 to 3 groups of C 1-6 alkyl, halogen, hydroxyl, (CH 2 ) n CF 3 , or CN; R a represents C 1-6 alkyl, halogen, hydroxyl, OR 2 (CH 2 ) n CF 3 , C 3-6 cycloalkyl, NR 2 C(O)R 2 , C(O)N(R 2 ) 2 , C(R 2 ) 2 OR 2 , C(O)R 2 , NO 2 , CN, N(R 2 ) 2 , C(O)OR 2 , SO 2 R 2 , OR 2 , (CH 2 ) n C 5-10 heterocyclyl, or (CH 2 ) n C 6-10 aryl, said heterocyclyl and aryl optionally substituted with 1 to 3 groups of C 1-6 alkyl, halogen, hydroxyl, (CH 2 ) n CF 3 ,or CN; R a' is C 1-6 alkyl, halogen, hydroxyl, OR 2 (CH 2 ) n CF 3 , NR 2 C(O)R 2 , C(O)N(R 2 ) 2 , C(R 2 ) 2 OR 2 , C(O)R 2 , NO 2 , CN, N(R 2 ) 2 , C(O)OR 2 , SO 2 R 2 , or OR 2 ; and n represents 0 to 4, provided that WZR 6 is not hydrogen. <EOS>