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2,6-difluorobenzamides have been deeply investigated as antibacterial drugs in the last few decades. Several 3-substituted-2,6-difluorobenzamides have proved their ability to interfere with the bacterial cell division cycle by inhibiting the protein FtsZ, the key player of the whole process. Recently, we developed a novel family of 1,4-tetrahydronaphthodioxane benzamides, having an ethoxy linker, which reached sub-micromolar MICs towards Gram-positive <i>Staphylococcus aureus</i> and <i>Bacillus subtilis</i>. A further investigation of their mechanism of action should require the development of a fluorescent probe, and the consequent definition of a synthetic pathway for its obtainment. In the present work, we report the obtainment of an unexpected bicyclic side product, 6-fluoro-3-(2,3,6,7,8,9-hexahydronaphtho[2,3-<i>b</i>][1,4]dioxin-2-yl)-2,3-dihydrobenzo[<i>b</i>][1,4]dioxine-5-carboxamide, coming from the substitution of one aromatic fluorine by the <i>in situ</i> formed alkoxy group, in the final opening of an epoxide intermediate. This side product was similarly achieved, in good yields, by opening the ring of both <i>erythro</i> and <i>threo</i> epoxides, and the two compounds were fully characterized using HRMS, ¹H-NMR, ¹³C-NMR, HPLC and DSC.