The invention relates to antibacterial compounds formula (I) wherein R1 is the group M, whereby M is one of the groups MA and MB represented below wherein A is a bond or C=C; R1A is H or halogen; R2A is H or halogen; R3A is H, alkoxy, hydroxyalkoxy, hydroxyalkyl, dihydroxyalkyl, 2-hydroxyacetamido, substituted cycloprop-1-yl or substituted oxetan-3-yl; and R1B is hydroxyalkyl, dihydroxyalkyl, aminoalkyl, dialkylaminoalkyl, substituted cycloprop-1-yl, substituted cyclobutan-1-yl, substituted oxetan-3-yl, 3-hydroxythietan-3-yl, substituted azetidin-3-yl, trans-(cis-3,4-dihydroxy)-cyclopent-1-yl, 3-hydroxymethylbicyclo[1,1,1]pentan-1-yl, 4-hydroxytetrahydro-2H-pyran-4-yl, (3R,6S)-3-aminotetrahydro-2H-pyran-6-yl, piperidin-4-yl or 1-(2-hydroxyacetyl)piperidin-4-yl; and salts thereof.