3101-96-0Relevant academic research and scientific papers
The preparation and characterization of benzocyclobutenylidene-, naphtho[b]cyclobutenylidene-, and η2-benzocyclobutadiene-η5-cyclopentadienyldicarbonyliron hexafluorophosphate
Sanders, Andrea,Bauch, Thomas,Magatti, Charles V.,Lorenc, Carol,Giering, Warren P.
, p. 359 - 375 (1976)
The preparation and characterization of the first isolable cationic mononuclear complexes bearing a η2-cyclobutadienoid ligand or a carbene ligand lacking heteroatom stabilization are described. The reaction between 1-bromo-benzocyclobutene and Na[η5-C5H5(CO)2Fe] (NaFp) afforded η1-1-benzocyclobutenyl-η5-cyclopentadienyldicarbonyliron (III). Treatment of III with trityl hexafluorophosphate gave benzocyclobutenylidene-η5-cyclopentadienyldicarbonyliron hexafluorophosphate (V). Naphtho [b] cyclobutenylidene-η5-cyclopentadienyldicarbonyliron hexafluorophosphate (VI) was formed in an analogous manner. Both V and VI gave 1,1-disubstituted cyclobutenes when treated with nucleophilic reagents. η2-Benzocyclobutadiene-η5-cyclopentadienyldicarbonyliron hexafluorophosphate, (XIX), which was prepared by the oxidation of bis-1,2-(η5-cyclopentadienyldicarbonyliron)benzocyclobutene by trityl hexafluorophosphate, afforded trans-1,2-disubstituted benzocyclobutenes when treated with nucleophilic reagents. The η2-benzocyclobutadiene ligand of XIX was displaced by I- and trapped as the Diels--Alder adduct by 1,3-diphenylisobenzofuran.
Elucidating the significance of β-hydride elimination and the dynamic role of acid/base chemistry in a palladium-catalyzed aerobic oxidation of alcohols
Mueller, Jaime A.,Goller, Christopher P.,Sigman, Matthew S.
, p. 9724 - 9734 (2004)
The mechanistic details of aerobic alcohol oxidation with catalytic Pd(I/Pr)(OAc)2(H2O) (I/Pr = 1,3-bis(2,6-diisopropylphenyl) imidazol-2-ylidene) are disclosed. Under optimal conditions, β-hydride elimination is rate-limiting supported by kinetic studies including a high primary kinetic isotope effect (KIE) value of 5.5 ± 0.1 and a Hammett p value of -0.48 ± 0.04. On the basis of these studies, a late transition state is proposed for β-hydride elimination, which is further corroborated by theoretical calculations using density functional theory. Additive acetic acid modulates the rates of both the alcohol oxidation sequence and regeneration of the Pd catalyst. With no additive [HOAc], turnover-limiting reprotonation of intermediate palladium peroxo is kinetically competitive with β-hydride elimination, allowing for reversible oxygenation and decomposition of Pd(O). With additive [HOAc] (>2 mol %), reprotonation of the palladium peroxo is fast and β-hydride elimination is the single rate-controlling step. This proposal is supported by an apparent decomposition pathway modulated by [HOAc], a change in alcohol concentration dependence, a lack of [O2] dependence at high [HOAc], and significant changes in the KIE values at different HOAc concentrations.
Mechanism of Electrochemical Generation and Decomposition of Phthalimide-N-oxyl
Yang, Cheng,Farmer, Luke A.,Pratt, Derek A.,Maldonado, Stephen,Stephenson, Corey R. J.
, p. 10324 - 10332 (2021)
PhthalimideN-oxyl (PINO) is a potent hydrogen atom transfer (HAT) catalyst that can be generated electrochemically fromN-hydroxyphthalimide (NHPI). However, catalyst decomposition has limited its application. This paper details mechanistic studies of the
Cobalt-Catalyzed Cyclization/Hydroboration of 1,6-Diynes with Pinacolborane
Huang, Qiang,Hu, Meng-Yang,Zhu, Shou-Fei
, p. 7883 - 7887 (2019)
Herein, we report a protocol for cyclization/hydroboration of 1,6-diynes with pinacolborane using a cobalt catalyst generated in situ from a Co(II)-phenanthroline complex, tetrabutylammonium fluoride, and pinacolborane. This protocol, which features good
A Heterogeneous Pt-ReOx/C Catalyst for Making Renewable Adipates in One Step from Sugar Acids
Jang, Jun Hee,Ro, Insoo,Christopher, Phillip,Abu-Omar, Mahdi M.
, p. 95 - 109 (2021/01/12)
Renewable adipic acid is a value-added chemical for the production of bioderived nylon. Here, the one-step conversion of mucic acid to adipates was achieved in high yield through deoxydehydration (DODH) and catalytic transfer hydrogenation (CTH) by a bifunctional Pt-ReOx/C heterogeneous catalyst with isopropanol as solvent and reductant. The Pt-ReOx/C catalyst is reusable and was regenerated at least five times. The catalyst exhibits a broad substrate scope of various diols. Spectroscopic studies of Pt-ReOx/C revealed ReVII and Pt0 as the relevant species for DODH and CTH, respectively. Isotope labeling experiments support a monohydride mechanism for CTH over Pt. This work demonstrates a reusable bifunctional catalyst for a one-step valorization of sugar acids to a practical monomer, which opens the door to multifunctional catalysis streamlining valorization of biomass-derived molecules.
Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
supporting information, p. 4119 - 4129 (2020/08/10)
A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
Gold-Catalyzed Friedel–Crafts-Like Reaction of Benzylic Alcohols to Afford 1,1-Diarylalkanes
Oakley, James V.,Stanley, Tyler J.,Jesse, Kate A.,Melanese, Amanda K.,Alvarez, Araceli A.,Prince, Aloha L.,Cain, Stephanie E.,Wenzel, Anna G.,Iafe, Robert G.
supporting information, p. 7063 - 7066 (2019/11/14)
A gold-catalyzed, Friedel–Crafts-like benzylation of unactivated benzylic alcohols to form 1,1-diarylalkanes has been developed. The operationally convenient method uses only 1.3 equivalents of the electron-rich arene, employs readily available starting m
Transfer Hydrogenation of Carbonyl Groups, Imines and N-Heterocycles Catalyzed by Simple, Bipyridine-Based MnI Complexes
Dubey, Abhishek,Rahaman, S. M. Wahidur,Fayzullin, Robert R.,Khusnutdinova, Julia R.
, p. 3844 - 3852 (2019/04/08)
Utilization of hydroxy-substituted bipyridine ligands in transition metal catalysis mimicking [Fe]-hydrogenase has been shown to be a promising approach in developing new catalysts for hydrogenation. For example, MnI complexes with 6,6′-dihydroxy-2,2′-bipyridine ligand have been previously shown to be active catalysts for CO2 hydrogenation. In this work, simple bipyridine-based Mn catalysts were developed that act as active catalysts for transfer hydrogenation of ketones, aldehydes and imines. For the first time, Mn-catalyzed transfer hydrogenation of N-heterocycles was reported. The highest catalytic activity among complexes with variously substituted ligands was observed for the complex bearing two OH groups in bipyridine. Deuterium labeling experiments suggest a monohydride pathway.
Transition-Metal-Free Hydrogen Autotransfer: Diastereoselective N-Alkylation of Amines with Racemic Alcohols
Xiao, Miao,Yue, Xin,Xu, Ruirui,Tang, Weijun,Xue, Dong,Li, Chaoqun,Lei, Ming,Xiao, Jianliang,Wang, Chao
supporting information, p. 10528 - 10536 (2019/07/17)
A practical method for the synthesis of α-chiral amines by alkylation of amines with alcohols in the absence of any transition-metal catalysts has been developed. Under the co-catalysis of a ketone and NaOH, racemic secondary alcohols reacted with Ellman's chiral tert-butanesulfinamide by a hydrogen autotransfer process to afford chiral amines with high diastereoselectivities (up to >99:1). Broad substrate scope and up to a 10 gram scale production of chiral amines were demonstrated. The method was applied to the synthesis of chiral deuterium-labelled amines with high deuterium incorporation and optical purity, including examples of chiral deuterated drugs. The configuration of amine products is found to be determined solely by the configuration of the chiral tert-butanesulfinamide regardless of that of alcohols, and this is corroborated by DFT calculations. Further mechanistic studies showed that the reaction is initiated by the ketone catalyst and involves a transition state similar to that proposed for the Meerwein–Ponndorf–Verley (MPV) reduction, and importantly, it is the interaction of the sodium cation of the base with both the nitrogen and oxygen atoms of the sulfinamide moiety that makes feasible, and determines the diastereoselectivity of, the reaction.
Iridium-catalyzed efficient reduction of ketones in water with formic acid as a hydride donor at low catalyst loading
Liu, Ji-Tian,Yang, Shiyi,Tang, Weiping,Yang, Zhanhui,Xu, Jiaxi
supporting information, p. 2118 - 2124 (2018/05/24)
A highly efficient and chemoselective transfer hydrogenation of ketones in water has been successfully achieved with our newly developed catalyst. Simple ketones, as well as α- or β-functionalized ketones, are readily reduced. Formic acid is used as a traceless hydride source. At very low catalyst loading (S/C = 10:000 in most cases; S/C = 50:000 or 100:000 in some cases), the iridium catalyst is impressively efficient at reducing ketones in good to excellent yields. The TOF value can be as high as up to 26:000 mol mol-1 h-1. A variety of functional groups are well tolerated, for example, heteroaryl, aryloxy, alkyloxy, halogen, cyano, nitro, ester, especially acidic methylene, phenol and carboxylic acid groups.
