- Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
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Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
- An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
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p. 6216 - 6226
(2020/04/27)
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- Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
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Efficient synthesis of primary amines via low-temperature reductive amination of carbonyl compounds using NH3 and H2 as the nitrogen and hydrogen resources is highly desired and challenging in the chemistry community. Herein, we employed naturally occurring phytic acid as a renewable precursor to fabricate titanium phosphate (TiP)-supported Ru nanocatalysts with different reduction degrees of RuO2 (Ru/TiP-x, x represents the reduction temperature) by combining ball milling and molten-salt processes. Very interestingly, the obtained Ru/TiP-100 had good catalytic performance for the reductive amination of carbonyl compounds at ambient temperature, resulting from the synergistic cooperation of the support (TiP) and the Ru/RuO2 with a suitable proportion of Ru0 (52%). Various carbonyl compounds could be efficiently converted into the corresponding primary amines with high yields. More importantly, the conversion of other substrates with reducible groups could also be achieved at ambient temperature. Detailed investigations indicated that the partially reduced Ru and the support (TiP) were indispensable. The high activity and selectivity of Ru/TiP-100 catalyst originates from the relatively high acidity and the suitable electron density of metallic Ru0.
- Xie, Chao,Song, Jinliang,Hua, Manli,Hu, Yue,Huang, Xin,Wu, Haoran,Yang, Guanying,Han, Buxing
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p. 7763 - 7772
(2020/08/21)
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- Asymmetric synthesis of primary amines catalyzed by thermotolerant fungal reductive aminases
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Chiral primary amines are important intermediates in the synthesis of pharmaceutical compounds. Fungal reductive aminases (RedAms) are NADPH-dependent dehydrogenases that catalyse reductive amination of a range of ketones with short-chain primary amines supplied in an equimolar ratio to give corresponding secondary amines. Herein we describe structural and biochemical characterisation as well as synthetic applications of two RedAms fromNeosartoryaspp. (NfRedAm andNfisRedAm) that display a distinctive activity amongst fungal RedAms, namely a superior ability to use ammonia as the amine partner. Using these enzymes, we demonstrate the synthesis of a broad range of primary amines, with conversions up to >97% and excellent enantiomeric excess. Temperature dependent studies showed that these homologues also possess greater thermal stability compared to other enzymes within this family. Their synthetic applicability is further demonstrated by the production of several primary and secondary amines with turnover numbers (TN) up to 14 000 as well as continous flow reactions, obtaining chiral amines such as (R)-2-aminohexane in space time yields up to 8.1 g L?1h?1. The remarkable features ofNfRedAmand NfisRedAm highlight their potential for wider synthetic application as well as expanding the biocatalytic toolbox available for chiral amine synthesis.
- Cosgrove, Sebastian C.,Grogan, Gideon,Mangas-Sanchez, Juan,Marshall, James R.,Palmer, Ryan B.,Ramsden, Jeremy I.,Sharma, Mahima,Thorpe, Thomas W.,Turner, Nicholas J.
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p. 5052 - 5057
(2020/06/09)
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- Reusable Nickel Nanoparticles-Catalyzed Reductive Amination for Selective Synthesis of Primary Amines
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The preparation of nickel nanoparticles as efficient reductive amination catalysts by pyrolysis of in situ generated Ni-tartaric acid complex on silica is presented. The resulting stable and reusable Ni-nanocatalyst enables the synthesis of functionalized and structurally diverse primary benzylic, heterocyclic and aliphatic amines starting from inexpensive and readily available carbonyl compounds and ammonia in presence of molecular hydrogen. Applying this Ni-based amination protocol, -NH2 moiety can be introduced in structurally complex compounds, for example, steroid derivatives and pharmaceuticals.
- Murugesan, Kathiravan,Beller, Matthias,Jagadeesh, Rajenahally V.
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supporting information
p. 5064 - 5068
(2019/03/19)
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- Chemoselective Photoredox Synthesis of Unprotected Primary Amines Using Ammonia
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Unprotected α-amino carbon radicals are produced as novel intermediates via a transformation that merges acid-promoted N-H imine generation and chemoselective photocatalytic single-electron reduction. Coupling ammonia and aldehydes/ketones allows the generation of primary amines under mild conditions without the need for protecting groups. The key intermediate can be efficiently transformed into primary (di)amines by a formal dimerization, reductive amination via hydrogen atom transfer, and arylation through radical-radical coupling.
- Rong, Jiawei,Seeberger, Peter H.,Gilmore, Kerry
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supporting information
p. 4081 - 4085
(2018/07/15)
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- MOF-derived cobalt nanoparticles catalyze a general synthesis of amines
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The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical preparation entailed template assembly of cobaltdiamine- dicarboxylic acid metal organic frameworks on carbon and subsequent pyrolysis under inert atmosphere.The resulting stable and reusable catalysts were active for synthesis of primary, secondary, tertiary, and N-methylamines (more than 140 examples).The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, or nitro compounds, and molecular hydrogen under industrially viable and scalable conditions, offering cost-effective access to numerous amines, amino acid derivatives, and more complex drug targets.
- Jagadeesh, Rajenahally V.,Murugesan, Kathiravan,Alshammari, Ahmad S.,Neumann, Helfried,Pohl, Marga-Martina,Radnik, J?rg,Beller, Matthias
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p. 326 - 332
(2017/09/28)
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- Heterogeneous Catalytic Reductive Amination of Carbonyl Compounds with Ni-Al Alloy in Water as Solvent and Hydrogen Source
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The heterogeneous catalytic reductive amination of carbonyl compounds has been achieved by reactions of ammonium hydroxide and various amines with ketones and aldehydes. The process is based on the application of Raney type Ni-Al alloy in an aqueous medium. The reaction of the carbonyl compounds with the amine provided the corresponding Schiff bases that immediately underwent a reduction to provide primary and secondary amines as products. The controlled reaction of the Al content of the alloy with the solvent water generates hydrogen, and the in situ formed Raney Ni serves as a hydrogenation catalyst. The method is a simple and efficient way of preparing a broad variety of primary and secondary amines.
- Sch?fer, Christian,Ni?anci, Bilal,Bere, Matthew P.,Da?tan, Arif,T?r?k, Béla
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p. 3127 - 3133
(2016/09/09)
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- Asymmetric Amination of Secondary Alcohols by using a Redox-Neutral Two-Enzyme Cascade
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Multienzyme cascade approaches for the synthesis of optically pure molecules from simple achiral compounds are desired. Herein, a cofactor self-sufficient cascade protocol for the asymmetric amination of racemic secondary alcohols to the corresponding chiral amines was successfully constructed by employing an alcohol dehydrogenase and a newly developed amine dehydrogenase. The compatibility and the identical cofactor dependence of the two enzymes led to an ingenious in situ cofactor recycling system in the one-pot synthesis. The artificial redox-neutral cascade process allowed the transformation of racemic secondary alcohols into enantiopure amines with considerable conversions (up to 94 %) and >99 % enantiomeric excess at the expense of only ammonia; this method thus represents a concise and efficient route for the asymmetric synthesis of chiral amines. If you know what amine: A redox-neutral two-enzyme cascade encompassing an alcohol dehydrogenase (ADH) and an amine dehydrogenase (AmDH) is constructed for the synthesis of chiral amines from the corresponding racemic alcohols in one pot to afford considerable conversions (up to 94 %) and high enantiomeric excess values (>99 %) at the expense of only ammonia.
- Chen, Fei-Fei,Liu, You-Yan,Zheng, Gao-Wei,Xu, Jian-He
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p. 3838 - 3841
(2016/01/26)
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- HIV INTEGRASE INHIBITORS
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The present invention features compounds that are HIV integrase inhibitors and therefore are useful in the inhibition of HIV replication, the prevention and/or treatment of infection by HIV, and in the treatment of AIDS and/or ARC.
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- Metal-free conversion of methane and cycloalkanes to amines and amides by employing a borylnitrene
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(Chemical Equation Presented) C-H insertion: Borylnitrenes, which are generated in situ by photoylsis of azides, convert unactivated alkanes by intermolecular C-H insertion into aminoboranes (see scheme), which in turn can be reacted further to give amines or amides. The boryl group serves two purposes: it converts the nitrene into a highly reactive BN vinylidene analogue, and it is easily cleaved from the product.
- Bettinger, Holger F.,Filthaus, Matthias,Bornemann, Holger,Oppel, Iris M.
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experimental part
p. 4744 - 4747
(2009/02/06)
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- Chemoselective reductive alkylation of ammonia with carbonyl compounds: Synthesis of primary and symmetrical secondary amines
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An efficient, general procedure for highly chemoselective reductive mono-alkylation of ammonia with ketones is reported. Treatment of ketones with ammonia in ethanol and titanium(IV) isopropoxide, followed by in situ sodium borohydride reduction, and a straightforward workup afforded primary amines in good to excellent yields. Reductive alkylation of ammonia with aldehydes, on the other hand, afforded the corresponding symmetrical secondary amines selectively.
- Miriyala, Bruhaspathy,Bhattacharyya, Sukanta,Williamson, John S.
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p. 1463 - 1471
(2007/10/03)
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- Non-metallocene compounds, method for the production thereof and use of the same for the polymerisation of olefins
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The invention relates to a method for producing special transition metal compounds, to novel transition metal compounds and to the use of the same for the polymerisation of olefins.
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- Tetracyclic benzimidazole derivatives and combinatorial libraries thereof
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The present invention relates to novel tetracyclic benzimidazole derivative compounds of the following formula: wherein R1to R10have the meanings described in here. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing tetracyclic benzimidazole derivative compounds.
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- Selective reductions. Part 60: Chemoselective reduction of organyl azides with dichloroborane-dimethyl sulfide
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The rate and stoichiometry of the reduction of an organyl azide with BH3·THF was examined under standardized conditions at room temperature. Borane derivatives, such as dialkyl-, alkoxy-, and haloboranes were also examined for the reduction of azides. This study revealed BHCl2·SMe2 to be the most suitable reagent for the reduction of azides. The chemoselectivity of this reagent was also studied by reducing n-hexyl azide in the presence of representative series of functional groups, including esters, halides, nitriles, and nitro groups. BHCl2·SMe2 reduces azides in the presence of all of the above functional groups as well as olefins. Taking advantage of the differences in reactivity of BHCl2·SMe2 and BH3·THF or BH3·SMe2, it is now possible to reduce selectively an azide in the presence of olefins or to hydroborate an olefin in the presence of azides by a judicious choice of the reagent.
- Salunkhe, Ashok M.,Veeraraghavan Ramachandran,Brown, Herbert C.
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p. 10059 - 10064
(2007/10/03)
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- 2-aminobenzoxazole derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminobenzoxazole derivative compounds of the following formula: wherein R1 to R4 and Z have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminobenzoxazole derivative compounds.
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- Selective monoalkylation of ammonia: A high throughput synthesis of primary amines
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Primary amines are obtained in good to excellent yields by highly selective monoalkylation of ammonia with alkyl and aryl ketones using titanium(IV) isopropoxide and sodium borohydride.
- Bhattacharyya, Sukanta,Neidigh, Kurt A.,Avery, Mitchell A.,Williamson, John S.
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p. 1781 - 1783
(2007/10/03)
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- DICHLOROBORANE-DIMETHYL SULFIDE, A HIGHLY SELECTIVE REDUCING AGENT FOR REDUCTION OF ORGANYL AZIDES TO AMINES
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Dichloroborane-dimethylsulfide reduces a variety of organyl azides, such as primary, secondary, tertiary, and aromatic to the corresponding amines in excellent yields.Cycloalkyl and benzylic azides are also readily reduced by this reagent.The reduction of azide with BHCl2*SMe2 is highly selective and many functional groups, such as halogen, ester, nitrile, aliphatic and armatic nitro, survice in this process.
- Salunkhe, Ashok M.,Brown, Herbert C.
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p. 7987 - 7990
(2007/10/02)
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- 3-amino-5-methyl-1H-pyrazole-4-carboxylic acids and esters thereof as anticonvulsants, muscle relaxants and anxiolytics
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A novel method of controlling epilepsy, muscle tension, muscular spasticity, and anxiety in living animal bodies by administering compounds of the formula: STR1 wherein: R1 is hydrogen, loweralkyl or a pharmaceutically acceptable cation; R2 and R3, same or different, are hydrogen, loweralkyl, aryl, cycloalkyl, loweralkenyl, 1-adamantyl, heterocyclicaminoalkyl, diloweralkylaminoloweralkyl, or R2 with R3 and adjacent nitrogen may form a heterocyclic ring structure; and the pharmaceutical acceptable acid salts, and tautomeric isomers thereof; and novel pharmaceutical compositions therefor are disclosed.
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- Very Soluble and Photostable Perylene Fluorescent Dyes
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The synthesis of perylene dyes 2 with two terminal alkyl groups is described.Long-chain alkyl groups do not increase, but diminish solubility.Cycloalkyl substituents give a minimum of solubility with medium sized rings and a maximum with the cyclotetradecyl derivative (2p).Very high solubility in organic solvents is attained by substitution with secondary alkyl residues having two long chains.One of them, the dye with the 1-hexylheptyl substituent (2v), exhibits a solubility of more than 100g/l in most solvents, a fluorescent quantum yield of about 100 percent, and a very high photostability, thus making it suitable for special applications.
- Demming, Stefan,Langhals, Heinz
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p. 225 - 230
(2007/10/02)
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- Imidazolylacetic acid amides
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Imidazolylacetic acid amides of the formula: SPC1 Or pharmaceutically acceptable nontoxic salts thereof wherein Either R1 is phenyl or cycloalkyl, unsubstituted or substituted by one or more substituents; and R2 is hydrogen; Or R1 and R2, together with the nitrogen atom to which they are attached, form a saturated 5 to 7-membered heterocyclic ring which ring may contain an --SO2 -- or --NY-- moiety wherein Y is alkoxycarbonyl, dialkylaminocarbonyl, or phenyl or diphenylmethyl, unsubstituted or substituted by one or more substituents and wherein said 5 to 7-membered heterocyclic ring itself is otherwise unsubstituted or substituted by one or more substituents; and X1, x2, x3 and X4 are the same or different and are each hydrogen or halogen, Are produced by A. reacting a halodiphenylacetic acid amide of the formula: SPC2 Wherein R1, r2, x1, x2, x3 and X4 are as above defined, and Hal is halogen, With imidazole; or B. reacting a halodiphenylacetic acid halide of the formula: SPC3 Wherein X1, x2, x3 and X4 are as above defined and Hal is halogen With imidazole to produce an imidazolide of the formula: SPC4 Wherein X1, x2, x3 and X4 are as above defined which in turn is transaminated by reaction with an amine of the formula: wherein R1 and R2 are as above defined.
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