Novel acylpiperazinones and their use as pharmaceuticals

A compound of formula (I):

• wherein:
• W, X and Y independently represent CH2 or C=0, wherein said CH2 group may be optionally independently substituted by a fluorine or (C1-C6) alkyl group, wherein said (C1-C6) alkyl group may be further substituted by one or two R5 groups;
• R1 represents H, (C1-C6) alkyl optionally substituted by a CONRaRb group, (C2-C6) alkenyl, (C2-C6) alkynyl, phenyl or a —Z-Het group, such that Z represents a bond or a linker selected from CO, (C1-C6) alkylene or —CO—(C1-C6) alkylene and Het represents a 4-6 membered monocyclic saturated or unsaturated heterocycle containing 1-3 heteroatoms selected from N, O and S, wherein said phenyl or heterocycle group of R1 may be optionally substituted by one or more (e.g. 1, 2 or 3) R5 groups;
• R2 represents H, CO2Ra, CORa, CONRaRb, CH2ORc, CH2NRaRb, SO2NRaRb or P(O)ORaORb;
• R3 represents halogen, (C1-C6) alkyl, (C2-C6) alkenyl or (C2-C6) alkynyl;
• R4 represents H, halogen, CN or CH3;
• Ra, Rb and Rc independently represent H, (C1-C6) alkyl, (C2-C6) alkenyl, (C2-C6) alkynyl, or an NRaR group may optionally form a 3- to 7-membered nitrogen containing saturated heterocycle optionally containing 1 to 3 additional heteroatoms selected from N, O or S wherein said heterocycle may be optionally substituted by one or more (C1-C6) alkyl groups;
• R5 represents halogen, CN, (C1-C6) alkyl, (C2-C6) alkenyl, (C2-C6) alkynyl, CO2Ra, CORa, CONRaRb OCORa, ORa, NRaRb, ON═CRaRb, NRcCORa, NRcCOORa, OCONRaRb, NRcCONRaRb, NRcSO2Ra, S(O)nRa, or SO2NRaRb;
• n represents an integer selected from 0 to 2;
• or a pharmaceutically acceptable salt or solvate thereof.