Phthalazinone derivatives

A compound of formula:

• 91
• or an isomer, salt, solvate, chemically protected form, or prodrug thereof, wherein:
• A and B together represent an optionally substituted, fused aromatic ring;
• RL is a C5-7 aryl group substituted in the meta position by the group R2, and optionally further substituted;
• wherein R2 is selected from:
• 92
• wherein:
• n is 0 or 1;
• Y is selected from NRN1 and CRC1RC2;
• RN1 is selected from H, optionally substituted C1-10 alkyl, optionally substituted C5-6 aryl and optionally substituted C1-10 alkylacyl;
• RC1, RC2, RC3, RC4, RC5, RC6, RC7 and RC8 are independently selected from H, R, SR and NHC(═O)OR, where R is optionally substituted C1-10 alkyl or optionally substituted C5-6 aryl;
• RC4 and RC6, RC6 and RC8 or RC8 and RC2 may optionally together form a double bond;
• RC1 and RC2, RC5 and RC6 or RC7 and RC8 together with the carbon atom to which they are attached may optionally form a spiro-fused C5-7 carbocylic or heterocyclic ring;
• and
• RC5 and RC7 or RC7 and RC1 together with the carbon atoms to which they are attached form an optionally substituted ring system;
• b)
• 93
• wherein
• m is 0 or 1;
• X is selected from NRN2 and CRC9RC10;
• RN2 is selected from H, optionally substituted C1-10 alkyl, optionally substituted C5-6 aryl and optionally substituted C1-10 alkylacyl;
• RC9, RC10, RC11, RC12, RC13 and RC14 are independently selected from H, R, SR and NHC(═O)OR, where R is as defined above;
• RC12 and RC10 or RC10 and RC14 may optionally together form a double bond;
• RC11 and RC12, RC9 and RC10 or RC13 and RC14 together with the carbon atom to which they are attached may optionally form a spiro-fused C5-7 carbocylic or heterocyclic ring;
• and
• RC11 and RC9 or RC9 and RC13 together with the carbon atoms to which they are attached may form an optionally substituted ring system.