New derivatives of cyclobutene dione, their process for the preparation and pharmaceutical compositions containing them

Cyclobutene dione derivatives (I) are new. Cyclobutene dione derivatives (I), their enantiomers and diastereoisomers, hydrates, solvates and acid addition salts, are new. X = mono- or bi-cyclic 5-12 membered heterocyclyl containing 1-3 O, N or S heteroatoms but at least one N atom (optionally substituted), and is linked to the remainder of the molecule through N, or -NR2R3; R2 = H or 1-6C alkyl; R3 = optionally substituted aryl, 1,3-dihydro-2H-benzimidazolyl-2-one, or 1-6C alkyl substituted by heterocyclyl as defined above; n = 0 or 1; R1 = H or 1-6C alkyl; Ra = a bond or 1-6C alkylene chain; A = N or CH, but when Ra is a bond, it is CH and when n is zero, it is N; E = N or CRe; Re = H or a bond to W; Rb = a bond, an 1-6C alkylene chain in which one of the C atoms may be replaced by O or S, and W = optionally substituted aryl or heteroaryl provided that at least one of A and E is N. An Independent claim is included for the preparation of (I).