Nickel-Catalyzed Allylic C(sp³)–F Bond Activation of Trifluoromethyl Groups via β-Fluorine Elimination: Synthesis of Difluoro-1,4-dienes

Abstract

The nickel-catalyzed defluorinative coupling of 2-trifluoromethyl-1-alkenes and alkynes with the aid of Et 3 SiH provides 1,1-difluoro-1,4-dienes under mild reaction conditions. This reaction involves selective allylic C(sp 3 )−F bond activation via β-fluorine elimination from nickelacyclopentenes.

Picking One out of Three: Selective Single C−F Activation in Trifluoromethyl Groups

“…Ichikawa developed the Ni 0 catalyzed synthesis of difluoro-1,4-dienes 18 via defluorinative coupling of trifluoromethylalkenes 16 and alkynes 17 in the presence of Et 3 SiH (Scheme7). [24] The reactioni sc ompatible with ar ange of a-trifluoromethylstyrene derivatives and severali nternal alkynes, as well as additional functional groups, such as esters or chlorine substituents. Mechanistic investigations revealed the initial formation of an ickelacyclopropane 19,w hich was observed by multinuclear NMR studies.…”

Ni-Catalyzed Borylation of Aryl Fluorides via C–F Cleavage

“…14,15 This protocol represents a powerful alternative to other borylation techniques based on more reactive carbon-halide bonds, 16 suggesting that iterative scenarios might come into play when dealing with the functionalization of polyhalogenated frameworks. This method is characterized by its wide substrate cope, and by obviating the need for stoichiometric organometallic reagents, representing a significant stepforward for the implementation of C-F bond-cleavage in cross-coupling reactions.…”

Fluorinative Rearrangements of Substituted Phenylallenes Mediated by (Difluoroiodo)toluene: Synthesis of α‐(Difluoromethyl)styrenes

“…Although a-(difluoromethyl)styrenes are precursors to polysubstituted fluoroalkene, [12] and novel fluorinated polymers, [13,14] there are no deoxyfluorination strategies reported for these species. [15] They have been prepared by direct fluorination using cesium fluoroxysulfate (CsSO 4 F), [16] however,t he typical approach involves olefination [12,17] or dehydration [13,18] of af luorinecontaining precursor.W eaimed to develop adirect synthesis of a-(difluoromethyl)styrenes through aT olIF 2 -mediated fluorinative rearrangement of phenylallene derivatives.…”