28994-41-4Relevant articles and documents
Ortho derivatization of phenols through C-H nickelation: Synthesis, characterization, and reactivities of ortho-nickelated phosphinite complexes
Vabre, Boris,Deschamps, Flix,Zargarian, Davit
, p. 6623 - 6632 (2014)
Reported here are the synthesis and characterization of ortho-nickelated complexes derived from phosphinite ligands and investigated as model compounds in the development of C-H functionalization strategies for arenol substrates. Reaction of i-Pr2POPh with 0.6 equiv of [(i-PrCN)NiBr2]n and 0.8 equiv of NEt3 in toluene (100 °C, 36 h) gave the yellow, monomeric cyclometalated complex trans-{κ2P,C-C6H4OP(i-Pr)2}Ni(i-Pr2POPh)Br (3a) in 93% yield. The closely related yellow-orange dimeric species [{κ2P,C-C6H4OP(i-Pr)2}Ni(μ-Br)]2 (4a) was obtained in 70% yield when i-Pr2POPh was treated with 2 equiv each of the Ni precursor and NEt3. These complexes have been characterized fully and shown to interconvert in the presence of excess ligand (4a → 3a) or excess Ni precursor (3a → 4a). Treatment of 3a or 4a with benzyl bromide at 90°C over extended periods led to benzylation of the Ni-aryl moiety in these complexes. Examination of the cyclometalation pathway for i-Pr2POPh has shown that the first species formed from its ambient-temperature reaction with [(i-PrCN)NiBr2]n is trans-(i-Pr2POPh)2NiBr2 (2a). NMR studies showed that 2a undergoes a rapid ligand exchange at room temperature, which can be slowed down at -68°C; this fluxional process shifts in the presence of NEt3, implying the partial formation of an amine adduct. Heating toluene mixtures of 2a and NEt3 at 90°C for 38 h led to the formation of 3a via C-H nickelation. That phosphinite dissociation from 2a precedes the C-H nickelation step is implied by the observation that the formation of 3a is hindered in the presence of excess i-Pr2POPh. The impact of phenol ring substituents on the C-H nickelation rate was probed by preparing substituted derivatives of 2a, trans-(4-R-C6H4OP(i-Pr2)}2NiBr2 (R = OMe (2b), Me (2c), COOMe (2d)), and measuring their relative rates of C-H nickelation. These studies showed that the formation of cyclonickelated products is favored in the order COOMe 6H4OP(i-Pr2) allowed us to establish that metalation is favored at the para position with respect to F (85:15).
Preparation method of diarylmethane and derivatives thereof
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Paragraph 0114-0117, (2021/04/21)
The invention discloses a preparation method of a diarylmethane compound and a derivative thereof. In a protective atmosphere, heating reaction is carried out on aryl aldehyde and an aromatic hydrocarbon compound in the presence of phosphorous acid and elemental iodine to obtain diarylmethane and the derivative thereof. According to the method, cheap and green solid phosphorous acid is selected as a reducing reagent and an accelerant for reaction, the diarylmethane and the derivative thereof are efficiently prepared by a one-pot one-step method starting from a simple and easily available aryl aldehyde compound in the presence of elemental iodine, and the method has the advantages of simplicity in operation, cheap and easily available reagents, environmental friendliness and the like; use of expensive reducing reagents, metal reagents and transition metal catalysts is avoided, and industrial production is facilitated.
Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
, p. 6107 - 6116 (2021/02/01)
Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.