Thiazoles and pyrazoles useful as kinase inhibitors

A compound of formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• X1 is N or CH;
• X2 is N or CH;
• X3 is N;
• provided that at least one of X1 and X2 is nitrogen;
• Ht is thiazole or pyrazole, wherein each ring is optionally and independently substituted with R2 and R2′;
• Q is —O—, —NR′—, —S—, —C(═O)—, or —C(R′)2—;
• RX is H or F;
• RY is —Z—R10;
• R1 is T-(Ring D);
• Ring D is a 5-7 membered monocyclic aryl or heteroaryl ring, wherein said heteroaryl has 1-4 ring heteroatoms selected from O, N, and S;
• Ring D can optionally be fused with Ring D′;
• Ring D′ is a 5-8 aromatic, partially saturated, or fully unsaturated ring containing 0-4 ring heteroatoms selected from nitrogen, oxygen or sulfur;
• Ring D and Ring D′ are each independently and optionally substituted with 0-4 occurrences of oxo or —W—R5;
• each T is independently a C1-4 alkylidene chain or is absent;
• R2 is H, C1-3 alkyl, or cyclopropyl;
• R2′ is H;
• each Z and W is independently a bond or a C1-10 alkylidene chain wherein up to six methylene units of the alkylidene chain are optionally replaced by V;
• each V is selected from —O—, —C(═O)—, —S(O)—, —S(O)2—, —S—, or —N(R4)—;
• each R5 is independently —R, -halo, —OR, —C(═O)R, —CO2R, —COCOR, COCH2COR, —NO2, —CN, —S(O)R, —S(O)2R, —SR, —N(R4)2, —CON(R7)2, —SO2N(R7)2, —OC(═O)R, —N(R)COR, —N(R7)CO2(C1-6 aliphatic), —N(R4)N(R4)2, —C═NN(R4)2, —C═N—OR, —N(R7)CON(R7)2, —N(R7)SO2N(R7)2, —N(R4)SO2R, or —OC(═O)N(R7)2;
• each R is hydrogen, a C1-6 aliphatic group, a C6-10 aryl ring, a heteroaryl ring having 5-10 ring atoms, or a heterocyclyl ring having 4-10 ring atoms;
• wherein said heteroaryl or heterocyclyl ring has 1-4 ring heteroatoms selected from nitrogen, oxygen, or sulfur;
• R is optionally substituted with 0-6 R9;
• each R4 is —R7, —COR7, —CO2R7, —CON(R7)2, or —SO2R7;
• each R6 is independently hydrogen or C1-6 alkyl;
• each R7 is independently hydrogen or an optionally substituted C1-6 aliphatic group;
• or two R7 on the same nitrogen are taken together with the nitrogen to form an optionally substituted 4-8 membered heterocyclyl or heteroaryl ring containing 1-4 heteroatoms selected from nitrogen, oxygen, or sulfur;
• each R9 is —R′, -halo, —OR′, —C(═O)R′, —CO2R′, —COCOR′, COCH2COR′, —NO2, —CN, —S(O)R′, —S(O)2R′, —SR′, —N(R′)2, —CON(R′)2, —SO2N(R′)2, —OC(═O)R′, —N(R′)COR′, —N(R′)CO2(C1-6 aliphatic), —N(R′)N(R′)2, —N(R′)CON(R′)2, —N(R′)SO2N(R′)2, —N(R′)SO2R′, —OC(═O)N(R′)2, ═NN(R′)2, ═N—OR′, or ═O;
• each R10 is a 4-membered heterocyclic ring containing 1 heteroatom selected from O, N, and S;
• each R10 is optionally substituted with 0-6 occurrences of J;
• each J is independently R, -halo, —OR, oxo, —C(═O)R, —CO2R, —COCOR, —COCH2COR, —NO2, —CN, —S(O)R, —S(O)2R, —SR, —N(R4)2, —CON(R7)2, —SO2N(R7)2, —OC(═O)R, —N(R7)COR, —N(R7)CO2(C1-6 aliphatic), —N(R4)N(R4)2, ═NN(R4)2, ═N—OR, —N(R7)CON(R7)2, —N(R7)SO2N(R7)2, —N(R4)SO2R, —OC(═O)N(R7)2, or —OP(═O)(OR″)2;
• or
• 2 J groups, on the same atom or on different atoms, together with the atom(s) to which they are bound, form a 3-8 membered saturated, partially saturated, or unsaturated ring having 0-2 heteroatoms selected from O, N, or S;
• wherein 1-4 hydrogen atoms on the ring formed by the 2 J groups is optionally replaced with halo, C1-3alkyl, or —O(C1-3alkyl);
• or two hydrogen atoms on the ring are optionally replaced with oxo or a spiro-attached C3-4 cycloalkyl;
• wherein said C1-3alkyl is optionally substituted with 1-3 fluorine;
• each R′ is independently hydrogen or a C1-6 aliphatic group;
• or two R′, together with atom(s) to which they are bound, form a 3-6 membered carbocyclyl or a 3-6 membered heterocyclyl containing 0-1 heteroatoms selected from O, N, and S;
• and
• each R″ is independently H or C1-2alkyl.