Lactivicin compounds, their preparation and use as antibacterial agents

A compound of formula (I)

• where A is defined by formula (Ia)
• and wherein X is N or CR3, and R3 represents hydrogen or halogen;
• R1 and R2, together with the carbon atom to which they are bonded, may form a (C3-C8) cycloalkyl, wherein
• (i) the cycloalkyl may contain one heteroatom selected from O, N and S, and/or
• (ii) the cycloalkyl may be substituted with one, two, three or four substituents selected independently of one another from the group consisting of (C1-C3) alkyl and halogen;
• or
• R1 and R2 may, independently of one another, represent hydrogen or (C1-C3) alkyl, wherein (C1-C3) alkyl may be substituted with a substituent selected from hydroxy and chlorine;
• B is a bicyclic catechol or hydroxypyridone moiety bearing fragment defined by formula (Ia′)
• wherein P is an unsaturated 5-membered or 6-membered ring, which optionally may contain one carbonyl (CO) group, or two carbonyl (CO) groups, or one sulfone (SO2) group, or a combination of one carbonyl (CO) and one sulfone (SO2) group, and may further contain up to two additional N atoms;
• and
• wherein Q may contain up to two N atoms, and wherein R4 is selected from the group consisting of hydrogen, (C1-C3) alkyl, carbonyl, trifluoromethyl, cyano and a halogen;
• and
• salts thereof, solvates thereof, and solvates of the salts thereof;
• and
• wherein compound I′″ is excluded from formula (I).