A compound having the formula I: ** Formula ** or a pharmaceutically acceptable salt thereof, wherein: D1 is C3-8 cycloalkyl, optionally substituted with 1 to 4 substituents independently selected from the group consisting of: C1-alkyl -8, amino, hydroxy, C1-8 alkylcarbonyl, aminocarbonyl, C1-8 alkoxycarbonylamino, C1-8 arylalkoxycarbonylamino, phenyl and heterocyclyl-C1-8alkylene； R1 is selected from the group consisting of H, C1-8alkyl, amino, aminocarbonyl, hydroxyl, C1-8alkoxy, halo C1-8alkyl, C2-8alkenyl, C2-8alkynyl, oxo, cyano, C1-8alkoxycarbonyl , C3-8 cycloalkyl, aryl and heterocyclyl； and each heterocyclyl is optionally substituted with 1 to 4 substituents selected from the group consisting of: C1-8-alkyl, halo, oxo, amino, C1-8-alkoxy, C1-8-alkylcarbonyl, aminocarbonyl, arylalkyl-C1-8-carbonylcarbonyl 8 and C1-8 alkylsulfonyl； Y1 is selected from the group consisting of (a) aryl； optionally substituted with 1 to 3 substituents, R4a, independently selected from the group consisting of C1-8 alkyl, C1-8 alkoxy-C1-8 alkyl, aminocarbonyl-, hydroxyl, oxo, halogen, hydroxy, C1-8 alkoxy and alkylsulfonyl C1-8； (b) heteroaryl, optionally substituted with 1 to 3 substituents, R4a, independently selected from the group consisting of C1-8-alkyl, C1-8-alkoxy-C1-8-alkyl, aminocarbonyl-, hydroxyl, oxo, halogen, hydroxy, alkoxy C1-8 and C1-8 alkylsulfonyl； R2 is a heterocyclyl or heteroaryl substituted with at least one group, R3, selected from the group consisting of aminoalkyl C1-8-, C1-8-alkoxy-C1-8-alkyl, oxo-, C1-8-alkylcarbonyl, C3-cycloalkylcarbonyl 8, heterocyclylcarbonyl, C1-8 alkylcarbonylamino, C3-8 cycloalkylcarbonylamino, heterocyclylcarbonylamino, C1-8 alkylsulfonyl, C3-8 cycloalkylsulfonyl, and heterocyclyl sulphonyl； and wherein R2 is optionally further substituted by 1 to 2 substituents, R4c, independently selected from the group consisting of C1-8 alkyl, C1-8 alkoxy, halo, aminocarbonyl, oxo, hydroxyl, C1-8 aminoalkylene, C1 alkoxy -8-C1-8 alkylene, C1-
