The objective of this final thesis was the preparation of chlorine substituted 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, BODIPY compounds which will later be utilized as precursors in the synthesis of a new fluorescent indicator, potential chemosensors or biological macromolecule marker. A series of reactions were conducted, the first one being the preparation of dipyrromethane by the Lindsey method, which uses pyrrole and benzaldehyde as starting molecules that undergo condensation with trifluoroacetic acid as catalyst. 5-Phenyldipyrromethane (5) was obtained in a very good reaction yield from two batches of the given reaction, which used different ratios of pyrrole and benzaldehyde. Dipyrromethane was then halogenated using N-chlorosuccinimide at two different temperatures. The acquired 1,1'-dichloro-5-phenyldipyrromethane (3) and 1-chloro-5-phenyldipyrromethane (4) were then, without prior isolation of the compounds, subjected to oxidation into the corresponding dipyrromethene using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) followed by complexation with boron trifluoride as a Lewis acid. 3,5-Dichloro-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (1) was isolated by preparative thin layer chromatography. The reactions were conducted in controlled, inert conditions while also being protected from the light. THF, toleuene and dichloromethane were used as solvents. All of the synthesised compounds were characterized using 1H and 13C NMR spectroscopic methods.