Catalytic Hydrosilylation of Hydrofluoroolefins (HFOs): Synthesis of New Fluorinated Silanes and Diversity of their Synthetic Character

Abstract

New polyfluorinated silanes were synthesized via the Pt, Rh and Pd catalyzed hydrosilylation of commercially available hydrofluoroolefins (HFOs) in moderate to excellent yields. HFO‐1234yf (2,3,3,3‐tetrafluoropropene‐1) and –1234ze (1,3,3,3‐tetrafluoropropene‐1) were reactive with Pt catalyst to form tetrafluoropropylsilanes along with defluorosilylation products. The Z‐ and E‐isomers of HFO‐1336mzz (1,1,1,4,4,4‐hexafluorobut‐2‐ene) gave the desired silanes with Pd catalysis in good to excellent yields, while with Pt catalyst only the dehydrofluorination product CF2=CHCH2CF3 (HFO‐1345czf, 1,1,4,4,4‐pentafluorobut‐1‐ene) was obtained. Synthetic applications of the new polyfluorinated silanes were illustrated by conversion of dichloro(hexafluorobutyl)(methyl)silane to the cyclic trisiloxane, which can serve as a monomer for the preparation of polysiloxanes. In addition, the hexafluorobutylsilanes showed defluorinative reactivity with lithium reagents, thereby demonstrating their synthetic utility as valuable building blocks for further transformations via C–F and C‐Si bond activation.

Iron-catalyzed cross-electrophile coupling of bromostyrenes and chlorosilanes

“…Recently, Shu and co-workers reported the method of Ni-catalyzed reductive C(sp 2 )–Si coupling of aryl/vinyl triflates with chlorohydrosilanes 12 b (Si–H: ∼77 kcal mol −1 and Si–Cl: ∼93 kcal mol −1 ) via using the unconventional Si–Cl cleavage to synthesize a series of organohydrosilanes. 15 Given the importance of organohydrosilanes in organosilicon chemistry as a class of fundamental materials, we also wondered whether our new strategy of Fe-catalyzed reductive vinylation of chlorosilanes can be extended to vinyl hydrosilane-forming reactions when chlorohydrosilanes are used. First, the previous Fe-catalyzed standard conditions (Table 1 entry 1) for the reductive coupling of ( E )-1-(2-bromovinyl)-4-methoxybenzene 1a with chlorodimethylsilane 1c gave 46 only in 65% yield.…”

Application of Industrially Relevant HydroFluoroOlefin (HFO) Gases in Organic Syntheses

“…They explored the reactivity of Pt, Rh and Pd catalysts in the reaction of different hydrosilanes and HFO gases. 59 Usually the reaction gave a mixture of products although by changing the catalyst system formation of a major product could be promoted. The described process was especially effective for the hydrosilylation of 1,1,1,4,4,4-hexafluorobut-2-ene (HFO 1336mzz, either E 86 or Z isomer 79) which was converted quantitatively and selectively to the hydrosylilated product (87, Scheme 13).…”

“…Besides substitution, Peng, Yagupolskii and co-workers conducted an extensive study of the hydrosilylation reaction of HFOs. 60 They explored the reactivity of Pt, Rh, and Pd catalysts in the reaction of different hydrosilanes and HFO gases. Generally the reaction gave a mixture of products although changing the catalyst system promoted the formation of one major product.…”

Competing C–H and C–F bond activation reactions of a fluorinated olefin at Rh: a fluorido vinylidene complex as an intermediate in an unprecedented dehydrofluorination step

“…[1][2][3][4][5] In this regard, both C-H and C-F bond activation reactions of HFOs have been described using transition metal complexes, main group elements or heterogeneous catalysts. [6][7][8][9][10][11][12] Commonly, the C-F bond activation is promoted by the formation of stable bonds such as H-F, B-F, Si-F or Al-F bonds among others. [13][14][15][16][17][18] At rhodium, the complexes [Rh(E)(PEt 3 ) 3 ] (E ¼ H, F, boryl, silyl, germyl) exhibit distinct reaction pathways for the C-F or C-H bond activation of HFOs.…”