Spiro-condensed pyrrolidine derivatives as deubiquitylating enzymes (DUB) inhibitors

A compound of formula I:

• a tautomer thereof, or a pharmaceutically acceptable salt of said compound or tautomer, wherein:
• R1a, R1b, R1c and R1d each independently represent hydrogen or C1-C6 alkyl;
• R1e and R1f each independently represent hydrogen or C1-C6 alkyl;
• ring A is a 5 to 6-membered monocyclic heterocyclyl ring, which in addition to the amide nitrogen optionally comprises 1 or 2 heteroatoms each independently selected from N, O and S;
• and which may be optionally substituted with one -Q1-(R2)n, wherein n is 1;
• and optionally one, two or three -Q1-(R2)n, wherein n is 0;
• wherein each -Q1-(R2)n is the same or different;
• when n is 0, Q1 represents halogen, cyano, oxo, hydroxyl, —NR3R4, —CONR3R4, —NR3COR4, NR3CONR4R4a, —COR3, —C(O)OR3, —C1-C6 alkyl, or —C1-C6 alkoxy;
• wherein the alkyl and alkoxy groups are optionally substituted with one to four halogen substituents;
• when n is 1, Q1 represents a covalent bond, an oxygen atom, a sulphur atom, —SO—, —SO2—, —CO—, —C(O)O—, —CONR3—, —NR3—, —NR3CO—, —NR3CONR4—, SO2NR3—, —NR3SO2—, —NR3SO2NR4—, —NR3C(O)O—, —NR3C(O)OR5—, C1-C6 alkylene, or —C2-C6 alkenylene;
• R2 represents a phenyl ring or a 5 to 10-membered heterocyclyl or heteroaryl ring, wherein said heterocyclyl and heteroaryl rings comprise 1, 2 or 3 heteroatoms, each independently selected from N, O and S;
• wherein said R2 ring is optionally substituted with one to two substituents independently selected from halogen, cyano, oxo, hydroxyl, —NR6R7, —CONR6R7, —NR6COR7, —NR6CONR7R7a, —COR6, —C(O)OR6, —C1-C6 alkyl, —C1-C6 alkoxy, -Q2a-R8, -Q2b-CONR6-Q2c-R8, and -Q2-NR6SO2-Q2c-R8;
• wherein the alkyl and alkoxy groups are optionally substituted with one to four substituents selected from halogen and hydroxyl;
• Q2a represents a covalent bond, an oxygen atom, a sulphur atom, —SO—, —SO2—, —CO—, or C1-C6 alkylene;
• Q2b and Q2c each represent a covalent bond;
• R3, R4 and R4a each independently represent hydrogen or C1-C6 alkyl;
• R6, R7 and R7a each independently represent hydrogen or C1-C6 alkyl;
• and
• R8 is selected from phenyl, piperazinyl, cyclopropyl, morpholinyl and piperidinyl;
• wherein R8 is optionally substituted by fluorine, chlorine, oxo, cyano, C1-C3 alkyl, or C1-C3 alkoxy.