Abstract: Compounds of formula (1) are inhibitors of HSP90 activity in vitro or in vivo, and of use in the treatment of inter alia, cancer: wherein R2 is a group of formula —(Ar1)m-(Alk1)P-(Z)r-(Alk2)S-Q wherein Ar1 is an optionally substituted aryl or heteroaryl radical, Alk? and Alk 2 are optionally substituted divalent C1-C3 alkylene or C2-C3 alkenylene radicals, m, p, r and s are independently 0 or 1, Z is —O—, —S—, —(C?O)—, —(C?S)—, —SO2—, —C(?O)O—, —C(?O)NRA—, —C(?S)NRA—, —SO2NRA—, —NRAC(?O)—, —NRASO2— or —NRA— wherein RA is hydrogen or C1-C6 alkyl, and Q is hydrogen or an optionally substituted carbocyclic or heterocyclic radical; R3 is hydrogen, an optional substituent, or an optionally substituted (C1-C6)alkyl, aryl or heteroaryl radical; and R4 is a carboxylic ester, carboxamide or sulfonamide group.

Abstract: Compounds of formula (1) are inhibitors of HSP90 activity in vitro or in vivo, and of use in the treatment of inter alia, Cancer: wherein R2 is a group of formula —(Ar1)m-(Alk1)P-(Z)r-(Alk 2)S-Q wherein Ar1 is an optionally substituted aryl or heteroaryl radical, Alk? and Alk 2 are optionally substituted divalent C1-C3 alkylene or C2-C3 alkenylene radicals, m, p, r and s are independently 0 or 1, Z is —O—, —S—, —(C?O)—, —(C?S)—, —SO2—, —C(?O)O—, —C(?O)NRA—, —C(?S)NRA—, —SO2NRA—, —NRAC(?O)_, —NRASO2- or —NRA—wherein RA is hydrogen or C1-C6 alkyl, and Q is hydrogen or an optionally substituted carbocyclic or heterocyclic radical; R3 is hydrogen, an optional substituent, or an optionally substituted (C1-C6)alkyl, aryl or heteroaryl radical; and R4 is a carboxylic ester, carboxamide or sulfonamide group.

Abstract: Compounds of formula (1) are inhibitors of HSP90 activity in vitro or in vivo, and of use in the treatment of inter alia, cancer: wherein R2 is a group of formula —(Ar1)m-(Alk1)P-(Z)r-(Alk2)S-Q wherein Ar1 is an optionally substituted aryl or heteroaryl radical, Alk? and Alk 2 are optionally substituted divalent C1-C3 alkylene or C2-C3 alkenylene radicals, m, p, r and s are independently 0 or 1, Z is -0-, —S—, —(C?O)—, —(C?S)—, -S02-, —C(?O)O—, —C(?O)NRA—, —C(?S)NRA—, -S02NRA—, —NRAC(?O)—, —NRAS02- or —NRA— wherein RA is hydrogen or C1-C6 alkyl, and Q is hydrogen or an optionally substituted carbocyclic or heterocyclic radical; R3 is hydrogen, an optional substituent, or an optionally substituted (C1-C6)alkyl, aryl or heteroaryl radical; and R4 is a carboxylic ester, carboxamide or sulfonamide group.

Abstract: Compounds of formula (1) are inhibitors of HSP90 activity in vitro or in vivo, and of use in the treatment of inter alia, cancer wherein R2 is a group of formula —(Ar1)m-(Alk1)P-(Z)r-(Alk2)S-Q wherein Ar1 is an optionally substituted aryl or heteroaryl radical, Alk? and Alk 2 are optionally substituted divalent C1-C3 alkylene or C2-C3 alkenylene radicals, m, p, r and s are independently 0 or 1, Z is —0—, —S—, —(C?O)—, —(C?S)—, —S02-, —C(?O)O—, —C(?O)NRA—, —C(?S)NRA—, —S02NRA—, —NRAC(?O)_, —NRAS02- or —NRA—wherein RA is hydrogen or C1-C6 alkyl, and Q is hydrogen or an optionally substituted carbocyclic or heterocyclic radical; R3 is hydrogen, an optional substituent, or an optionally substituted (C1-C6)alkyl, aryl or heteroaryl radical; and R4 is a carboxylic ester, carboxamide or sulfonamide group.