- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
-
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
-
supporting information
p. 9029 - 9039
(2021/06/28)
-
- Mechanistic Characterization of (Xantphos)Ni(I)-Mediated Alkyl Bromide Activation: Oxidative Addition, Electron Transfer, or Halogen-Atom Abstraction
-
Ni(I)-mediated single-electron oxidative activation of alkyl halides has been extensively proposed as a key step in Ni-catalyzed cross-coupling reactions to generate radical intermediates. There are four mechanisms through which this step could take place: oxidative addition, outer-sphere electron transfer, inner-sphere electron transfer, and concerted halogen-atom abstraction. Despite considerable computational studies, there is no experimental study to evaluate all four pathways for Ni(I)-mediated alkyl radical formation. Herein, we report the isolation of a series of (Xantphos)Ni(I)-Ar complexes that selectively activate alkyl halides over aryl halides to eject radicals and form Ni(II) complexes. This observation allows the application of kinetic studies on the steric, electronic, and solvent effects, in combination with DFT calculations, to systematically assess the four possible pathways. Our data reveal that (Xantphos)Ni(I)-mediated alkyl halide activation proceeds via a concerted halogen-atom abstraction mechanism. This result corroborates previous DFT studies on (terpy)Ni(I)- and (py)Ni(I)-mediated alkyl radical formation, and contrasts with the outer-sphere electron transfer pathway observed for (PPh3)4Ni(0)-mediated aryl halide activation. This study of a model system provides insight into the overall mechanism of Ni-catalyzed cross-coupling reactions and offers a basis for differentiating electrophiles in cross-electrophile coupling reactions.
- Diccianni, Justin B.,Katigbak, Joseph,Hu, Chunhua,Diao, Tianning
-
supporting information
p. 1788 - 1796
(2019/01/26)
-
- Photocatalytic carbanion generation-benzylation of aliphatic aldehydes to secondary alcohols
-
We present a redox-neutral method for the photocatalytic generation of carbanions. Benzylic carboxylates are photooxidized by single electron transfer; immediate CO2 extrusion and reduction of the in situ formed radical yields a carbanion capable of reacting with aliphatic aldehydes as electrophiles giving the Grignard analogous reaction product.
- Donabauer, Karsten,Maity, Mitasree,Berger, Anna Lucia,Huff, Gregory S.,Crespi, Stefano,K?nig, Burkhard
-
p. 5162 - 5166
(2019/06/05)
-
- AN IMPROVED METHOD FOR THE PREPARATION OF ALKYLENEDIOXYBENZENE COMPOUNDS
-
This invention relates to an improved method for preparing alkylenedioxybenzene compounds of Formula I, from the corresponding ortho-dihydroxy aromatic compound of Formula II wherein n is 0, 1, 2 or 3; and R1 and R2 independently represent H, linear or branched C1 – C10 alkyl or alkenyl group, cycloalkyl group, halogen selected from C1, Br, I, nitro (-NO2), alkoxy (-OR) or SR thioether (-SR), wherein R is linear or branched alkyl group comprising C1-C6 carbon atoms.
- -
-
Page/Page column 15
(2017/10/13)
-
- En Route to a Practical Primary Alcohol Deoxygenation
-
A long-standing scientific challenge in the field of alcohol deoxygenation has been direct catalytic sp3 C-O defunctionalization with high selectivity and efficiency, in the presence of other functionalities, such as free hydroxyl groups and amines widely present in biological molecules. Previously, the selectivity issue had been only addressed by classic multistep deoxygenation strategies with stoichiometric reagents. Herein, we propose a catalytic late-transition-metal-catalyzed redox design, on the basis of dehydrogenation/Wolff-Kishner (WK) reduction, to simultaneously tackle the challenges regarding step economy and selectivity. The early development of our hypothesis focuses on an iridium-catalyzed process efficient mainly with activated alcohols, which dictates harsh reaction conditions and thus limits its synthetic utility. Later, a significant advancement has been made on aliphatic primary alcohol deoxygenation by employing a ruthenium complex, with good functional group tolerance and exclusive selectivity under practical reaction conditions. Its synthetic utility is further illustrated by excellent efficiency as well as complete chemo- and regio-selectivity in both simple and complex molecular settings. Mechanistic discussion is also included with experimental supports. Overall, our current method successfully addresses the aforementioned challenges in the pertinent field, providing a practical redox-based approach to the direct sp3 C-O defunctionalization of aliphatic primary alcohols.
- Dai, Xi-Jie,Li, Chao-Jun
-
supporting information
p. 5433 - 5440
(2016/05/19)
-
- Endothelin antagonists benzene oxygen benzene acetic acids and its preparation method and application
-
The invention provides a phenoxy phenylacetic acid endothelin antagonist shown in a formula (I) or a pharmaceutically acceptable salt thereof, and also provides a preparation method of the benzene oxygen phenylacetic acid endothelin antagonist or the pharmaceutically acceptable salt thereof, and an application thereof in preparation of a medicament for treating cardiovascular and cerebrovascular diseases, tumors, diabetes mellitus, nephrosis, asthma or hyperthyroidism.
- -
-
Paragraph 0072-0074
(2016/11/02)
-
- The genetic incorporation of thirteen novel non-canonical amino acids
-
Thirteen novel non-canonical amino acids were synthesized and tested for suppression of an amber codon using a mutant pyrrolysyl-tRNA synthetase-tRNAPylCUA pair. Suppression was observed with varied efficiencies. One non-canonical amino acid in particular contains an azide that can be applied for site-selective protein labeling. The Royal Society of Chemistry 2014.
- Tuley, Alfred,Wang, Yane-Shih,Fang, Xinqiang,Kurra, Yadagiri,Rezenom, Yohannes H.,Liu, Wenshe R.
-
supporting information
p. 2673 - 2675
(2014/03/21)
-
- Iridium-catalyzed direct dehydroxylation of alcohols
-
Iridium-catalyzed direct dehydroxylation of alcohols with hydrazine was developed through a combination of the oxidation of alcohols and the Wolff-Kishner reduction. This protocol is simple to perform and highly efficient for a series of primary, benzylic and allylic alcohols. Iridium-catalyzed direct dehydroxylation of alcohols with hydrazine is developed through a combination of the oxidation of alcohols and Wolff-Kishner reduction. This protocol is simple to perform and highly efficient for a series of primary alcohols, especially benzylic and allylic ones. Copyright
- Huang, Jian-Lin,Dai, Xi-Jie,Li, Chao-Jun
-
supporting information
p. 6496 - 6500
(2013/11/06)
-
- Rhodium-catalyzed reductive decyanation of nitriles using hydrosilane as a reducing agent: Scope, mechanism and synthetic application
-
A rhodium-catalyzed reductive cleavage reaction of carbon-cyano bonds is developed using hydrosilane as a mild reducing agent. A wide range of nitriles, including aryl, benzyl, and p-hydrogen containing alkyl cyanides are applicable to this decyanation reaction. The method is also applicable to organic synthesis, in which benzyl cyanide is used as a benzyl anion equivalent and a cyano group functions as a removable ortho-directing group.
- Tobisu, Mamoru,Nakamura, Ryo,Kita, Yusuke,Chatani, Naoto
-
scheme or table
p. 582 - 587
(2010/08/07)
-
- Nickel boride-mediated cleavage of 1,3-dithiolanes: A convenient approach to reductive desulfurization
-
1,3-Dithiolanes are rapidly cleaved by nickel boride, generating corresponding hydrocarbons in excellent yields. The hydrogenolysis is rapid at room temperature and does not require protection from the atmosphere. Mild reaction conditions, simple workup, and good yields of pure products are some of the major advantages of the procedure.
- Khurana, Jitender M.,Magoo, Devanshi
-
experimental part
p. 2908 - 2913
(2010/10/19)
-
- SUBSTITUTED THIOPHENES
-
Disclosed herein are substituted pyrimidine-based endothelin modulators of Formula I, processes of preparation thereof, pharmaceutical compositions thereof, and methods of use thereof.
- -
-
Page/Page column 66
(2008/12/04)
-
- Method For Producing Optionally Substituted Methylenedioxybenzene
-
The invention relates to a method for producing optionally substituted methylenedioxybenzene. The invention particularly relates to the production of methylenedioxybenzene. The inventive production method is characterized by the fact that it involves the reaction of an optionally substituted catechol with an aldehyde in the presence of a solid acid catalyst selected among: a titanium silicalite and a zeolite that is doped with tin and/or titanium.
- -
-
Page/Page column 5
(2008/06/13)
-
- A solvent-controlled highly efficient Pd-C catalyzed hydrogenolysis of benzaldehydes to methylbenzenes via a novel 'acetal pathway'
-
Pd-C catalyzed hydrogenolysis of benzaldehydes to methylbenzenes has been described to proceed via a 'benzenemethanol pathway'. In this article, a novel 'acetal pathway' was first revealed by a systematic study when lower alcohols were used as solvents and a solvent-controlled highly efficient procedure was established.
- Xing, Lixin,Wang, Xinyan,Cheng, Chuanjie,Zhu, Rui,Liu, Bo,Hu, Yuefei
-
p. 9382 - 9386
(2008/02/10)
-
- Indolocarbazole anticancer agents and methods of using same
-
The present invention relates to anti-tumor compounds, compositions and methods. In particular, the invention relates to indolocarbazole analogues of the following general formulas that inhibit topoisomerase I activity. 1
- -
-
-
- A re-examination of the methylenation reaction
-
A re-examination of the methylenation reaction of 1-hydroxy-2-mercapto-, 1,2-dihydroxy- and 1,2-dimercapto-substituted benzenes by bromochloromethane with cesium carbonate shows that these substrates give mixtures of five- and ten-membered benzocondensed heterocyclic compounds and in some cases even dibenzodioxines.
- Cabiddu, Maria Grazia,Cadoni, Enzo,De Montis, Stefania,Fattuoni, Claudia,Melis, Stefana,Usai, Michele
-
p. 4383 - 4387
(2007/10/03)
-
- Indolocarbazole anticancer agents and methods of using them
-
The present invention relates to anti-tumor compounds, compositions and methods. In particular, the invention relates to indolocarbazole analogues of the following general formulas that inhibit topoisomerase I activity. 1
- -
-
-
- The Huang-Minlon modification of Wolff-Kishner reduction in rapid and simple way using microwave technology
-
A high yielding, simple and fast method for the reduction of various aldehydes and ketones to the respective hydrocarbons following Huang-Minlon modification tender microwave irradiation is described.
- Chattopadhyay, Sarmishtha,Banerjee, Sajal Kumar,Mitra, Alok Kumar
-
p. 906 - 907
(2007/10/03)
-
- Aryl radical cyclizations of 1-(2′-bromobenzyl)isoquinolines with AIBN-Bu3SnH: Formation of aporphines and indolo[2,1-a]isoquinolines
-
(matrix presented) Radical cyclization of alkoxy-substituted 1-(2′-bromobenzyl)-3,4-dihydroisoquinolines 1 with AIBN-Bu3SnH gave 6a,7-dehydroaporphines 2 preferentially. A steric repulsion between the respective alkoxy groups at the 7- and 3′-positions gave 5,6-dihydroindolo[2,1-a]isoquinolines 3 in a disfavored 5-endo cyclization mode. Radical cyclizations of the related substrates, such as 1-(2′-bromobenzoyl)isoquinolines or 1-(2′-bromo-α-hydroxybenzyl)isoquinolines, were also found to give the corresponding oxoaporphines or oxyaporphines.
- Orito, Kazuhiko,Uchiito, Shiho,Satoh, Yoshitaka,Tatsuzawa, Takashi,Harada, Rika,Tokuda, Masao
-
p. 307 - 310
(2007/10/03)
-
- Process for the preparation of aromatic compounds containing a heterocyclic system
-
Process for the preparation of aromatic compounds containing a heterocyclic system, having general formula (II): STR1 which comprises reacting catechol, optionally substituted, with a methylene dihalide in a basic environment and in the presence of a solvent medium consisting of N-methylpyrrolidone.
- -
-
-
- Process for the preparation of aromatic compounds containing a heterocyclic system
-
Process for the preparation of aromatic compounds containing a heterocyclic system, having general formula (II): which comprises reacting catechol, optionally substituted, with a methylene dihalide in a basic environment and in the presence of a solvent medium consisting of N-methylpyrrolidone.
- -
-
-
- THE ESR SPECTRA, STRUCTURE, AND REACTIVITY OF AROMATIC RADICAL-CATIONS IN SUPERACIDS
-
The oxidation of aromatic compounds by lead dioxide in superacids based on fluorosulfonic acid at -75 deg C takes place by a one-electron mechanism and leads in many cases to relatively stable radical-cations.The ESR spectra, the isotropic hyperfine coupling constants, data on the reactivity of the radical-cations, and the structures of the final products from their transformations under "long-life" conditions are presented.
- Rudenko, A. P.
-
p. 1946 - 1980
(2007/10/03)
-
- ELECTROCHEMICAL OXIDATION OF ORGANIC COMPOUNDS IN FLUOROSULFONIC ACID. IX. VOLTAMMETRIC CHARACTERISTICS OF THE OXIDATION OF SUBSTITUTED PHENOLS, THEIR DERIVATIVES, AND HETEROCYCLIC COMPOUNDS IN FLUOROSULFONIC ACID AND ACETONITRILE
-
The electrochemical oxidation of phenols and their alkyl ethers not containing strong electron-withdrawing substituents in fluorosulfonic acid takes place in the form of the benzenonium ions and is irreversible in character.With the introduction of substituents of the -M type into the benzene ring the oxidation process affects the unprotonated molecules to a first approximation and in many cases goes reversibly to the radical-cations.Comparison of the oxidation potentials of the substrates in acetonitrile and fluorosulfonic acid made it possible to reveal certain characteristics of the fine structure of these radical-cations, which is determined by the ability of the latter to interact with the medium.Heterocyclic cations whose oxidation potentials in acetonitrile lie beyond the limit of the discharge of the supporting electrolyte can be oxidized in fluorosulfonic acid.Cations of the quinolinium, isoquinolinium, acridinium, acridizinium, imidazolium, and other series, which have irreversible many-electron waves in acetonitrile, give well-defined reversible peaks for oxidation to the corresponding radical-dications in fluorosulfonic acid.In phenyl- and benzyl-substituted cations the substituents and not the positively charged heterocycle itself can undergo oxidation.
- Rudenko, A. P.,Zarubin, M. Ya.,Pragst, F.
-
p. 2145 - 2165
(2007/10/02)
-
- Reductive Cleavage of Aryl Oxazolines to Benzaldehydes and Substituted Toluenes
-
Aryl oxazolines have been converted to their corresponding benzaldehydes and toluenes by several routes by passing through the intermediate amino alcohols.The transformations proceeded under mild conditions and were shown to be generally applicable to a variety of substitutions on the aromatic nucleus.
- Meyers, A. I.,Himmelsbach, Richard J.,Reuman, Michael
-
p. 4053 - 4058
(2007/10/02)
-
- The Constituents of Schizandra chinensis BAILL. IX. The Cleavage of the Methylenedioxyl Moiety with Lead Tetraacetate in Benzene, and the Structure of Angeloylgomisin Q
-
A procedure for selective cleavage of the methylenedioxyl moiety with lead tetraacetate in dry benzene is described.Piperonylic acid methyl ester (5), 4-nitro-1,2-methylenedioxybenzene (6), 3,4-methylenedioxytoluene (7), 2,3-methylenedioxyanisole (8) and gomisin A (9) afforded protocatechuic acid (12), 4-nitrocatechol (13), 3,4-dihydroxytoluene(14), 2,3-dihydroxyanisole (15) and compound 16, respectively.The structure of angeloylgomisin Q isolated from the fruits of Schizandra chinensis BAILL. (Schizandraceae), was elucidated as 1 by using the above reaction.Keywords--cleavage of methylenedioxyl moiety; lead tetraacetate; Schizandra chinensis BAILL.; Schizandraceae; dibenzocyclooctadiene; lignan; angeloylgomisin Q
- Ikeya, Yukinobu,Taguchi, Heihachiro,Yoshioka, Itiro
-
p. 2893 - 2898
(2007/10/02)
-