Isothiazole derivatives useful as anticancer agents

A compound of the formula

• or a pharmaceutically acceptable salt, prodrug or solvate thereof, wherein,
• X1 is O or S;
• R1 is —(CH2)t(4-5 membered heterocyclic), wherein t is an integer from 0 to 5;
• said heterocyclic group is optionally fused to a C6-C10aryl group, a C5-C8 saturated cyclic group, or a 5-10 membered heterocyclic group;
• and said R1 group, including the optionally fused portions of said R1 group, is optionally substituted by 1 or 2 substituents independently selected from C1-C4 alkyl, hydroxy and hydroxymethyl;
• R2 is H;
• R3 is H, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, —(CH2)t(C6-C10 aryl), or —(CH2)t(5-10 membered heterocyclic), wherein t is an integer from 0 to 5;
• said alkyl group optionally include 1 or 2 hetero moieties selected from O, S and —N(R6)— with the proviso that two O atoms, two S atoms, or an O and S atom are not attached directly to each other;
• said aryl and heterocyclic R3 groups are optionally fused to a C6-C10 aryl group, a C5-C8 saturated cyclic group, or a 5-10 membered heterocyclic group;
• 1 or 2 carbon atoms in the foregoing heterocyclic moieties are optionally substituted by an oxo (═O) moiety;
• the —(CH2)t— moieties of the foregoing R3 groups optionally include a carbon-carbon double or triple bond where t is an integer from 2 to 5, and the foregoing R3 groups are optionally substituted by 1 to 5 R4 groups;
• each R4 is independently selected from C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, halo, cyano, nitro, trifluoromethyl, trifluoromethoxy, azido, —OR5, —C(O)R5, —C(O)OR5, —NR6C(O)OR5, —OC(O)R5, —NR6SO2R5, —SO2NR5R6, —NR6C(O)R5, —C(O)NR5R6, —NR5R6, —S(O)jR7 wherein j is an integer ranging from 0 to 2, —SO3H, —NR5(CR6R7)tOR6, —(CH2)t(C6-C10 aryl), —SO2(CH2)t(C6-C10 aryl), —S(CH2)t(C6-C10 aryl), —O(CH2)t(C6-C10 aryl), —(CH2)t(5-10 membered heterocyclic), and —(CR6R7)mOR6, wherein m is an integer from 1 to 5 and t is an integer from 0 to 5;
• said alkyl group optionally contains 1 or 2 hetero moieties selected from O, S and —N(R6)— with the proviso that two O atoms, two S atoms, or an O and S atom are not attached directly to each other;
• said aryl and heterocyclic R4 groups are optionally fused to a C6-C10 aryl group, a C5-C8 saturated cyclic group, or a 5-10 membered heterocyclic group;
• 1 or 2 carbon atoms in the foregoing heterocyclic moieties are optionally substituted by an oxo (═O) moiety;
• and the alkyl, aryl and heterocyclic moieties of the foregoing R4 groups are optionally substituted by 1 to 3 substituents independently selected from halo, cyano, nitro, trifluoromethyl, trifluoromethoxy, azido, —NR6SO2R5, —SO2NR5R6, —C(O)R5, —C(O)OR5, —OC(O)R5, —NR6C(O)R5, —C(O)NR5R6, —NR5R6, —(CR6R7)mOR6 wherein m is an integer from 1 to 5, —OR5 and the substituents listed in the definition of R5;
• each R5 is independently selected from H, C1-C10 alkyl, —(CH2)t(C6-C10 aryl), and —(CH2)t(5-10 membered heterocyclic), wherein t is an integer from 0 to 5;
• said alkyl group optionally includes 1 or 2 hetero moieties selected from O, S and —N(R6)— with the proviso that two O atoms, two S atoms, or an O and S atom are not attached directly to each other;
• said aryl and heterocyclic R5 groups are optionally fused to a C6-C10 aryl group, a C5-C8 saturated cyclic group, or a 5-10 membered heterocyclic group;
• and the foregoing R5 subsituents, except H, are optionally substituted by 1 to 3 substituents independently selected from halo, cyano, nitro, trifluoromethyl, trifluoromethoxy, azido, —C(O)R6, —C(O)OR6, —CO(O)R6, —NR6C(O)R7, —C(O)NR6R7, —NR6R7, hydroxy, C1-C6 alkyl, and C1-C6 alkoxy;
• and
• each R6 and R7 is independently H or C1-C6 alkyl.