Push-pull Benzophenone-type Photoredox Catalyst Useful for C(sp²)-C(sp³) Cross-coupling Reactions

4-Methoxy-4'-trifluoromethylbenzophenone (1) is a benzophenone derivative with an electron-withdrawing trifluoromethyl group and an electron-donating methoxy group. Under light irradiation, benzophenone derivatives are excited to triplet state and generate biradical species. As a result, they can be used as photoredox catalysts to facilitate energy transfer (ET), single electron transfer (SET), and hydrogen atom transfer (HAT). However, the excitation of benzophenone requires high-energy UV light, which can easily degrade the substrates. On the other hand, the absorption wavelength of 1 is shifted to the longer wavelength side due to its push-pull structure. Therefore, 1 can be used as a photoredox catalyst that can react under milder conditions. Its use as a catalyst for C(sp²)-C(sp³) cross-couplings has been reported. For example, under fluorescent light irradiation, the cross-coupling between aryl bromides and saturated heterocyclic rings proceeds in the presence of catalytic amounts of 1, Ni(acac)₂ and 6,6'-di-3-picolyl, along with stoichiometric amounts of sodium carbonate.¹⁾ 1 can also generate silyl radicals by HAT from tris(trimethylsilyl)silane. Silyl radicals have also been reported to generate alkyl radicals by halogen atom transfer (XAT), enabling reductive cross-coupling reactions between aryl bromides and alkyl bromides.²⁾

Related Products

T4165

4-Methoxy-4'-trifluoromethylbenzophenone

N0096

Bis(2,4-pentanedionato)nickel(II) Hydrate (= Ni(acac)₂)

B2138

6,6'-Di-3-picolyl

S0560

Sodium Carbonate (= Na₂CO₃)

T1463

Tris(trimethylsilyl)silane (= (TMS)₃SiH)

L0067

2,6-Lutidine

References

• 1) sp³ C−H Arylation and Alkylation Enabled by the Synergy of Triplet Excited Ketones and Nickel Catalysts
  • Y. Shen, Y. Gu, R. Martin, J. Am. Chem. Soc. 2018, 140, 12200.
• 2) The Merger of Benzophenone HAT Photocatalysis and Silyl Radical-Induced XAT Enables Both Nickel-Catalyzed Cross-Electrophile Coupling and 1,2-Dicarbofunctionalization of Olefins
  • A. Luridiana, D. Mazzarella, L. Capaldo, J. A. Rincón, P. García-Losada, C. Mateos, M. O. Frederick, M. Nuño, W. J. Buma, T. Noël, ACS Catal. 2022, 12, 11216.

Page Top