Titanium‐Catalyzed C–F Activation of Fluoroalkenes

Abstract

Detox: air-stable titanocene difluoride efficiently catalyzes the chemoselective hydrodefluorination of fluoroalkenes at room temperature leading to hydrofluoroalkenes in high yields (see scheme: Cp=cyclopentadienyl). This is a rare example of the catalyzed conversion of fluoroalkenes into less-fluorinated compounds, which have a lower climatic impact, and is a potential method for breaking down toxic perfluoroalkenes.

Catalytic Transformations of Fluorinated Olefins

“…Thus, in the presence of diphenylsilane and a catalytic amount of Cp 2 TiF 2 , the hydrodefluorination of hexafluoropropylene takes place at room temperature very smoothly, resulting in the formation of an E/Z mixture of 1,2,3,3,3-pentafluoropropane (Scheme 2) [22,23]. In this hydrodefluorination system, secondary silanes such as Ph 2 SiH 2 act as the best hydride source, and cyclopentadienyl ligands with a low steric hindrance and a high electron density have shown better catalytic performance.…”

Influence of the Diphosphine Coordinated to Molybdenum and Tungsten Triangular M3S4 Cluster Hydrides in the Catalytic Hydrodefluorination of Pentafluoropyridine

“…The reaction occurs with high efficiency (turnover numbers of 67) and high selectivity at the four-position in which the ligands play a pivotal role in the reaction yield. Kühnel and Lentz reported on the catalytic hydrodefluorination of hexafluoropropene using titanocene dihalides as precatalysts and a silane as the hydrogen source [14].…”

Reactions of Fluoroalkenes with an Aluminium(I) Complex

“…[8][9][10] Based on the emerging trends,t here is ac lear advantage to developing new chemical transformations that use fluoroalkenes as fluorinated chemical building blocks.H owever, to date the majority of reactions of HFOs involve either C À C or CÀHbond formation, thereby limiting the opportunity for further synthetic elaboration. [11][12][13][14][15][16][17] Only recently have methods emerged to convert unreactive CÀFb onds of HFOs into C À B, C À Si, or C À Ge bonds.F or example, Hosoya and coworkers presented an elegant defluoroborylation of (E)-1,3,3,3-tetrafluoropropene and 2,3,3,3-tetrafluoropropene with B 2 pin 2 (bis(pinacolato)diborane) using catalytic copper salts in the presence of abase. [18,19] In related studies,B raun and coworkers have documented the hydroboration, hydrosilylation, and hydrogermylation of aseries of fluoroalkenes (including HFOs) by Lewis acidic heterogeneous catalysts or homogeneous rhodium catalysts.T hese hydrofunctionalisation reactions often lead to complex mixtures of products because of competing addition and elimination pathways.…”