Pheophytin(Pheo)‐a as the free base of chlorophyll(Chl)‐a, was fluorinated at the 20‐position using N‐fluorobenzenesulfonimide, followed by insertion of a magnesium cation at the central position to afford 20‐fluoro‐Chl‐a. On the other hand, 32,32‐difluoro‐Chl‐a was obtained from Pheo‐d possessing the 3‐formyl group by the Wittig reaction using (triphenylphosphonio)difluoroacetate and the successive magnesium insertion. The synthetic 20‐fluoro‐ and 32,32‐difluoro‐Chls‐a showed similar optical properties and enzymatic hydrolysis of the phytyl ester to original (intact) Chl‐a. By contrast, their 132‐stereochemical inversion (epimerization) occurred more rapidly, and the removal of their central magnesium (pheophytinization) was more tolerant than Chl‐a due to the electronic effect of the fluorine atom(s) through the chlorin π‐system in a molecule. Since a fluorine atom is comparable in the size to a hydrogen atom, these chemically stable fluorinated Chls‐a are promising as the synthetic alternatives to naturally occurring Chl‐a, and are useful for the structural and functional investigation in oxygenic phototrophs.

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