α-Fluoroallenoate Synthesis via N-Heterocyclic Carbene-Catalyzed Fluorination Reaction of Alkynals

The first catalytic alpha-fluoroallenoate synthesis is described. With a suitable combination of N-heterocyclic carbene precatalyst, base, and fluorine reagent, the reaction proceeded smoothly to yield a wide range of alpha-fluoroallenoates with excellent chemoselectivity. These substituted alpha-fluorinated allenoates have been synthesized for the first time, and they are versatile synthetic intermediates toward other useful fluorine-containing building blocks.