Pyrazolo[1,5-A]pyrimidines as mark inhibitors

A compound of formula I:

• or a pharmaceutically acceptable salt or hydrate thereof;
• wherein:
• X1 is selected from the group consisting of:
• H, halogen, C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-6cycloalkyl, C1-6alkoxy, —C(O)—OC1-4alkyl, C3-6cycloalkoxy, CN and N(R3)2, wherein said C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-6cycloalkyl, C1-6alkoxy, —C(O)—OC1-4alkyl and C3-6cycloalkoxy are optionally substituted up to the maximum number of substitutable positions with halogen;
• X2 is selected from the group consisting of:
• H, halogen, C3-6cycloalkyl, C1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-6cycloalkenyl, —CN, nitro and N(R3)2;
• said C1-6alkyl optionally substituted with up to 3 halogen atoms and said C2-6alkenyl and C2-6alkynyl optionally substituted with up to 3 R5 groups;
• R1 represents H or C1-4alkyl which is optionally substituted with OH, CN, CF3, C1-4alkoxy, amino, C1-4alkylamino or di(C1-4alkyl)amino;
• R2 is selected from:
• (i) H;
• (ii) C1-8alkyl or C2-8alkenyl, either of which optionally bears up to 3 substituents independently selected from halogen, OH, CN, CF3, OR3, SR4, SO2R4, SO2N(R3)2, COR3, CO2R3, CON(R3)2, N(R3)2, NR3COR4, NR3SO2R4 and phenyl, said phenyl bearing 0 to 5 halogen substituents;
• and
• (iii) C3-10cycloalkyl, C3-10cycloalkylC1-4alkyl, Het, HetC1-4alkyl, aryl or arylC1-4alkyl, any of which optionally bears up to 4 substituents independently selected from halogen, OH, oxo, CN, CF3, R4, OR3, SR4, SO2R4, SO2N(R3)2, COR3, CO2R3, CON(R3)2, N(R3)2, NR3COR4, NR3SO2R4 and —P(O)—(OR3)2;
• where “aryl” refers to phenyl or 5- or 6-membered heteroaryl, either of which phenyl or heteroaryl is optionally fused to a 5- or 6-membered carbocycle or heterocycle, “Het” refers to a nonaromatic or partially aromatic mono -or bicyclic heterocyclic system of up to 10 ring atoms and C3-10cycloalkyl and the cyclic portion of C3-10cycloalkylC1-4alkyl may be fused with phenyl or a 5- or 6-membered heteroaryl;
• or R1 and R2 together may complete a mono- or bicyclic heterocyclic system of up to 10 ring atoms which optionally bears up to 3 substituents independently selected from halogen, OH, oxo, CN, CF3, R4, OR3, SR4, SO2R4, SO2N(R3)2, COR3, CO2R3, CON(R3)2, N(R3)2, NR3COR4 and NR3SO2R4;
• each R3 independently represents H or C1-6alkyl which is optionally substituted with up to 3 halogen atoms or with OH, CN, CF3, C1-4alkoxy, amino, C1-4alkylamino or di(C1-4alkyl)amino;
• R4 has the same definition as R3 except that R4 is not H;
• and
• R5 is selected from the group consisting of:
• phenyl, hydroxy, C3-6cycloalkyl, and C1-4alkoxy.