32266-22-1Relevant academic research and scientific papers
Iron/N-doped graphene nano-structured catalysts for general cyclopropanation of olefins
Bartling, Stephan,Beller, Matthias,Ferretti, Francesco,Formenti, Dario,Junge, Kathrin,Kreyenschulte, Carsten,Ragaini, Fabio,Sarkar, Abhijnan
, p. 6217 - 6221 (2020/08/24)
The first examples of heterogeneous Fe-catalysed cyclopropanation reactions are presented. Pyrolysis of in situ-generated iron/phenanthroline complexes in the presence of a carbonaceous material leads to specific supported nanosized iron particles, which are effective catalysts for carbene transfer reactions. Using olefins as substrates, cyclopropanes are obtained in high yields and moderate diastereoselectivities. The developed protocol is scalable and the activity of the recycled catalyst after deactivation can be effectively restored using an oxidative reactivation protocol under mild conditions. This journal is
Hypervalent-iodine(iii) oxidation of hydrazones to diazo compounds and one-pot nickel(ii)-catalyzed cyclopropanation
Liu, Haixuan,Wei, Yunyang,Cai, Chun
, p. 674 - 678 (2016/01/12)
A one-pot process for the catalytic cyclopropanation of various alkenes with unsubstituted hydrazones is described. Iodosobenzene (Ph = O) was found to be a competent oxidant of hydrazones to diazo compounds. Ni(OH)2 was chosen as an effective and cheap metal catalyst. The cyclopropane products can be generated efficiently (5 min-4 h) in moderate to good yields (42-91%) under mild (80°C) and neat conditions.
DIKETIMINATO CU(I) AND CO(I) CARBENE CATALYSTS, AND CYCLOPROPANATION METHODS USING THEM
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Page/Page column 45, (2008/06/13)
The present invention described herein employs employs Cu(I) complexes of an electron-rich, bidentate N,N-donor ligand (P-diketiminates) that react with both heteroatomcontaining a-substituted diazomethanes and ary1diazomethanes to yield a unique metal-carbene complex stabilized by two metal fragments that selectively reacts with alkenes. These examples are the first of isolable Cu-carbene complexes that react with alkenes to give cyclopropanes. Furthermore, electron-rich, bidentate N,N-donor ligands can be designed to impart stereo- and enantio-selectivity in the cyclopropanation of alkenes with diazoalkanes.
Discrete bridging and terminal copper carbenes in copper-catalyzed cyclopropanation
Dai, Xuliang,Warren, Timothy H.
, p. 10085 - 10094 (2007/10/03)
The Cu(I)/ β-diketiminate [Me2NN]Cu(η2- ethylene) (2) catalyzes the cyclopropanation of styrene with N 2CPh2 to give 1,1,2-triphenylcyclopropane in 67% yield. Addition of N2CPh2 to 2 equiv of 2 allows for the isolation of the dicopper carbene {[Me2NN]Cu}2(μ- CPh2) (3) in which the diphenylcarbene moiety is symmetrically bound between two [Me2NN]Cu fragments (Cu-C = 1,922(4) and 1.930(4) A) with a Cu-Cu separation of 2.4635(7) A. In toluene-d8 solution, 3 reversibly dissociates a [Me2NN]Cu fragment to give [Me2NN]Cu(toluene) and the terminal carbene [Me2NN]Cu= CPh2, Dicopper carbene 3 reacts with 3 equiv of styrene to give 1,1,2-triphenylcyclopropane and 2 equiv of [Me2NN] Cu(η2-styrene) within minutes, DFT studies with simplified ligands indicate a stronger Cu-C π-back-bonding interaction from two Cu(I) centers to the carbene acceptor orbital in a dicopper carbene than that present in a monocopper carbene. Nonetheless, the terminal carbene [Me 3NN]Cu=CPh2 (8) that possesses a p-methyl group on each β-diketiminato N-aryl ring may be isolated and exhibits a shortened Cu-C distance of 1,834(3) A, The stoichiometric cyclopropanation of styrene by 8 in 1,4-dioxane is first-order in both copper carbene 8 and styrene with activation parameters ΔH? = 10,4(3) kcal/mol and ΔS? = -32,3(9) cal/mol·K. In 1,4-dioxane, 8 decomposes to Ph 2C=CPh2 via first-order kinetics with activation parameters ΔH? = 21(1) kcal/mol and ΔS? = -8(3) cal/mol·K. Arene solutions of thermally sensitive terminal carbene 8 decompose to [Me3NN]-Cu(arene), which reacts with 8 still present in solution to give the more thermally stable {[Me3NN]Cu} 2-(μ-CPh2).
Half-sandwich ruthenium(II) complexes of aminophosphines: Synthesis, structures and catalytic applications in C-C coupling reactions between styrenes and diphenyldiazomethane
Priya, Srinivasan,Balakrishna, Maravanji S.,Mobin, Shaikh M.,McDonald, Robert
, p. 227 - 235 (2007/10/03)
The half-sandwich Ru(II) complexes of the type [CpRu(PPh2 N(H)R)(PPh3)Cl], [CpRu(PPh2N(H)R)2Cl] (R=Ph, C6H11) and [CpRu(PPh2N(R′) PPh2-κP,κP)(PPh3)]Cl (R′=Et, nPr, iPr, nBu), were synthesized and the structures of complexes [CpRu(PPh2N(H)Ph)(PPh3) Cl] and [CpRu(PPh2N(H)Ph)2Cl] were confirmed by single crystal X-ray diffraction studies. All ruthenium complexes were employed in the cyclopropanation reaction of styrene derivatives in the presence of diphenyldiazomethane. All complexes afford 1,1,3,3-tetraphenyl cyclobutane along with cyclopropane derivatives; complex, [CpRu(PPh2N(nBu)PPh2-κ P,κP) (PPh3)]Cl shows better selectivity in the formation of 1,1,2-triphenylcyclopropane. In all reactions appreciable amounts of cyclopropanation products and metathesis products, 1,2-diphenylcyclopropane and 1,1-diphenylethene were obtained along with 1,1,3-triphenylpropene derivatives. The variable temperature NMR studies have suggested that the cyclopropanation reactions in the presence of ionic complex, [CpRu(PPh2N(R′)PPh 2-κP,κP)(PPh3)]Cl proceeds via carbene intermediate, [CpRu(=CPh2)(PPh2N(R′) PPh2-κP)(PPh3)]Cl.
