Formation and reactivity of gem-difluoro-substituted pyridinium ylides: Experimental and DFT investigation

▶ Addition of CF2 to pyridines is a reversible process. ▶ gem-Difluoro-substituted pyridinium ylides are thermodynamically unstable 1,3-dipoles. ▶ gem-Difluoro-substituted pyridinium ylides with π-acceptor substituents can be trapped with active dipolarophiles to give 3-fluoroindolizines.