Ir-Catalyzed Formal 1,2-Fluorine Migration in Fluorocarbenes
Yi-Jun Xiang1,2, Bai-Yu Qian1,2, Li-Yang Wan1
1Department of Chemistry, College of Sciences, Shanghai University, 200444 Shanghai, China.
None:
1,2-Fluorine migration in fluorocarbenes has long posed a formidable challenge, hindered by prohibitively high kinetic barriers. Herein, we report a formal 1,2-fluorine migration of trifluoromethyl and pentafluoroethyl diazo compounds catalyzed by a porphyrin-supported iridium complex under mild conditions, enabling straightforward access to structurally diverse fluorinated alkenes. Mechanistic investigations and density functional theory (DFT) calculations elucidate a catalytic cycle involving iridium-carbene formation and intermolecular fluoride transfer, wherein fluoride serves as a chain carrier to promote the formal 1,2-fluorine migration. This catalytic platform overcomes the intrinsic limitations of fluorine migration in fluorocarbenes and provides a complementary synthetic route to valuable fluorinated alkene scaffolds.
Related Concept Videos
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene
Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Mechanism


