Compounds of the Formula I, wherein A1 is O or NH; A2 is O or S; each of R1 and R2 is independently hydrogen, a methyl or C2-C8-saturated or mono- or doubly unsaturated, branched or linear hydrocarbon group; and R3 is a C1-C18-saturated or mono- or doubly unsaturated, branched or linear hydrocarbon group wherein, each of R1, R2 and R3 comprises a heteroatom selected from the group consisting of O and S in the chain and/or is mono- or multiply-substituted by a substituent selected from the group consisting of halogen, hydroxy, C1-C6-alkyl, trifluoromethyl, C1-C6-alkoxy, C6-C10-aryl, and C1-C6-alkyl-C6-C10-aryl are useful for controlling the interaction process between microorganisms such as in the development and/or maturation of biofilms; multicellular swarm behavior; the concerted development of antibiotic resistances; the concerted synthesis of antibiotics; the concerted synthesis of pigments; the concerted production of extracellular enzymes; or the concerted production of virulence factors.