I want to fluorinate the methylene hydrogens between an aryl group and a phosponate ester. The reaction is similar (not identical) to this one:
For some reason on the literature people are using very frequently NaHDMS as a base and seemingly exclusively N-fluorobenzenesulfonimide (NFSi) for this purpose. I tried to achieve the fluorination with selectfluor, but according to the UV signal at 254 nm, the product is only formed in minor quantities. Why is NFSi here supposably the superior fluorination agent? When I do research on the topic on almost every metric, selectfluor always is the fluorination agent described as the most reactive agent with the biggest kinetic constants like here:
https://onlinelibrary.wiley.com/doi/abs/10.1002/0471264180.or069.02
