Nfluorobenzenesulfonimide

N-fluorobenzenesulfonimide, commonly abbreviated as NFSI, is a solid electrophilic fluorinating agent used to introduce fluorine into a wide range of organic substrates. The molecule features a nitrogen bound to a fluorine atom and two benzenesulfonyl groups, forming an N–F bond within a sulfonimide framework. It is valued for delivering electrophilic fluorine under relatively mild conditions and can participate in catalytic and non-catalytic fluorination processes.

NFSI is typically a stable, bench-ready reagent, generally described as a white to off-white crystalline solid. It is soluble in many organic solvents such as dichloromethane and acetonitrile, with limited solubility in water. It is commercially available and can be prepared by fluorinating benzenesulfonimide or related precursors in specialized facilities.

In synthetic organic chemistry, NFSI is employed to effect electrophilic fluorination of diverse nucleophiles, including enolates, silyl enol ethers, and various carbon-centered nucleophiles. It is used in copper- and radical-catalyzed fluorination protocols and has been applied in enantioselective fluorination strategies using chiral catalysts. The reagent offers a practical alternative to elemental fluorine or other fluorinating agents, providing a reliable source of electrophilic fluorine in a range of transformations.

Safety and handling notes indicate that NFSI can be an irritant and should be handled with appropriate protective equipment under standard laboratory practices. It should be stored dry and kept away from sources of moisture and heat.

See also electrophilic fluorinating agents such as Selectfluor; reviews on electrophilic fluorination methods provide broader context for NFSI applications.

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