One of a number of lipophilic, long acyl side-chain bearing AHLs produced by the LuxI AHL synthase homolog SinI involved in quorum-sensing signaling in Sinorhizobium meliloti, a nitrogen-fixing bacterial symbiont of certain legumes; the most abundant AHL produced by the proteobacterium Rhodobacter capsulatus; activates genetic exchange between R. capsulatus cells.