Catalysis-chemistry

Manna, Kuntal published the artcileHighly enantioselective zirconium-catalyzed cyclization of aminoalkenes, Name: 2,2-Diallylpent-4-en-1-amine, the publication is Journal of the American Chemical Society (2013), 135(19), 7235-7250, database is CAplus and MEDLINE.

Group 4 half-sandwich cyclopentadienyl complexes with pendant chiral oxazoline ligands were prepared and examined as catalysts for enantioselective intramol. hydroamination of alkenamines, yielding chiral 5-7-membered saturated nitrogen heterocycles. Aminoalkenes are catalytically cyclized in the presence of cyclopentadienylbis(oxazolinyl)borato group 4 complexes {PhB(¦Ç⁵-C₅H₄)(Ox^R)₂}M(NMe₂)₂ (M = Ti, Zr, Hf; Ox^R = 4,4-dimethyl-2-oxazoline, 4S-isopropyl-5,5-dimethyl-2-oxazoline, 4S-tert-butyl-2-oxazoline) at room temperature and below, affording five-, six-, and seven-membered N-heterocyclic amines with enantiomeric excesses of >90% in many cases and up to 99%. Mechanistic investigations of this highly selective system employed synthetic tests, kinetics, and stereochem. Secondary aminopentene cyclizations require a primary amine (1-2 equiv vs. catalyst). Aminoalkenes are unchanged in the presence of a zirconium monoamido complex {PhB(C₅H₄)(Ox^4S-iPr,Me₂)₂}Zr(NMe₂)Cl or a cyclopentadienylmono(oxazolinyl)borato zirconium diamide {Ph₂B(C₅H₄)(Ox^4S-iPr,Me₂)}Zr(NMe₂)₂. Plots of initial rate vs. [substrate] show a rate dependence that evolves from first-order at low concentration to zero-order at high concentration, and this is consistent with a reversible substrate-catalyst interaction preceding an irreversible step. Primary kinetic isotope effects from substrate conversion measurements (k’_obs^(H)/k’_obs^(D) = 3.3 ¡À 0.3) and from initial rate anal. (k₂^(H)/k₂^(D) = 2.3 ¡À 0.4) indicate that a N-H bond is broken in the turnover-limiting and irreversible step of the catalytic cycle. Asym. hydroamination/cyclization of N-deutero-aminoalkenes provides products with higher optical purities than obtained with N-protio-aminoalkenes. Transition state theory, applied to the rate constant k₂ that characterizes the irreversible step, provides activation parameters consistent with a highly organized transition state (¦¤S? = -43(7) cal¡¤mol^-1 K^-1) and a remarkably low enthalpic barrier (¦¤H? = 6.7(2) kcal¡¤mol^-1). A six-centered, concerted transition state for C-N and C-H bond formation and N-H bond cleavage involving two amidoalkene ligands is proposed as most consistent with the current data.

Journal of the American Chemical Society published new progress about 928836-00-4. 928836-00-4 belongs to catalysis-chemistry, auxiliary class Alkenyl,Amine,Aliphatic hydrocarbon chain, name is 2,2-Diallylpent-4-en-1-amine, and the molecular formula is C11H19N, Name: 2,2-Diallylpent-4-en-1-amine.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Weidlich, Frauke published the artcileMild C-F Activation in Perfluorinated Arenes through Photosensitized Insertion of Isonitriles at 350 nm, Application In Synthesis of 1206-46-8, the publication is Advanced Synthesis & Catalysis (2020), 362(2), 376-383, database is CAplus.

Herein a method for the photochem. activation of aromatic C-F bonds is presented. It is shown that isonitriles RNC (R = 9-oxo-9H-xanthen-2-yl, 1-phenylethan-1-one, 2H-1,3-benzodioxol-5-yl, etc.) selectively insert into aromatic C-F bonds while aliphatic C-F bonds remain unaffected. Mechanistic studies reveal the reaction to proceed via the indirect excitation of the isonitrile to its triplet state by photoexcited acetophenone at 350 nm. Due to the relatively mild light used, the process shows that high functional group tolerance and various compounds of the class of benzimidoyl fluorides (Z)-RN=C(F)R¹ (R¹ = pentafluorophenyl, tetrafluoropyridin-3-yl, 3-chloro-2,4,5,6-tetrafluorophenyl, etc.) are accessible from aryl isonitriles and com. available perfluorinated arenes such as hexafluorobenzene, Me pentafluorobenzoate, perfluoropyridine, etc.

Advanced Synthesis & Catalysis published new progress about 1206-46-8. 1206-46-8 belongs to catalysis-chemistry, auxiliary class Organic Silicones, name is Trimethyl(perfluorophenyl)silane, and the molecular formula is C8H15NO, Application In Synthesis of 1206-46-8.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Stache, Erin E. published the artcileGeneration of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage-Independent Activation of Strong C-O Bonds, Formula: C15H24S, the publication is ACS Catalysis (2018), 8(12), 11134-11139, database is CAplus and MEDLINE.

Benzylic alcs. and aryl and alkylcarboxylic acids underwent photochem. deoxygenative reduction via phosphoranyl radicals in the presence of an iridium photoredox catalyst, either Ph₃P or Ph₂POEt, and an aryl disulfide or thiol to yield methylarenes and aryl and alkyl aldehydes. Carboxylic acids with pendant carbonyl groups or alkenes underwent cyclization reactions via acyl radicals in the presence of the iridium photoredox catalyst, Ph₂POEt, and an aryl thiol to yield lactones, a lactam, and cyclic ketones.

ACS Catalysis published new progress about 22693-41-0. 22693-41-0 belongs to catalysis-chemistry, auxiliary class Other Functionalization Reagent, name is 2,4,6-Triisopropylbenzenethiol, and the molecular formula is C4H11NO, Formula: C15H24S.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Fedorov, Andrei V. published the artcileNew Method To Reduce Oxygen Surface Inhibition by Photorelease of Boranes from Borane/Amine Complexes, Related Products of catalysis-chemistry, the publication is Macromolecules (Washington, DC, United States) (2007), 40(10), 3554-3560, database is CAplus.

A new photochem. approach for free radical polymerization has been developed. The system releases trialkylborane from its complex with 4-(dimethylamino)pyridine upon irradiation The presence of a free borane in the formulation, when it encounters oxygen, promotes radical polymerization The system, when irradiated by an ergonomic 395 nm LED array, is able to efficiently overcome surface oxygen inhibition. The properties of the resulting photopolymer surfaces either matched or exceeded those of controls polymerized under N₂ atmosphere or with high-intensity light source. Results of exptl. and computational studies probing the mechanism of borane photorelease are also discussed. Safety consideration, all reagents and reaction mixture in synthesis af amine-borane complexes should be kept under dry Ar atm. since triethylborane is pyrophoric.

Macromolecules (Washington, DC, United States) published new progress about 2909-77-5. 2909-77-5 belongs to catalysis-chemistry, auxiliary class Amine,Benzene, name is 2,6-Diisopropyl-N,N-dimethylaniline, and the molecular formula is C14H23N, Related Products of catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Castillo Melean, Johnny published the artcileA three-step radiosynthesis of 6-[¹⁸ F]fluoro-L-meta-tyrosine starting with [¹⁸ F]fluoride, COA of Formula: C17H37NO3, the publication is Journal of Labelled Compounds and Radiopharmaceuticals (2015), 58(3), 133-140, database is CAplus and MEDLINE.

The radiosynthesis of 6-[¹⁸ F]fluoro-L–m-tyrosine has generally been performed by electrophilic radiofluorination, which exhibits several drawbacks. In the present work, a three-step radiochem. synthesis is described starting from [¹⁸ F]fluoride. The synthetic sequence, including isotopic exchange, Baeyer-Villiger oxidation, and hydrolysis, were examined comparing four fluorobenzophenone derivatives as labeling precursors. Of those, (2S,5S)-tert-Bu 5-(5-acetyl-2-fluorobenzyl)-2-tert-butyl-3-methyl-4-oxoimidazolidine-1-carboxylate and (2S,5S)-tert-Bu 2-tert-butyl-5-(2-fluoro-5-(2,2,2-trifluoroacetyl)benzyl)-3-methyl-4-oxoimidazolidine-1-carboxylate proved to be the most suitable ones. 6-[¹⁸ F]Fluoro-L-m-tyrosine was obtained with overall radiochem. yields of 8-13% and an enantiomeric excess of up to 98%.

Journal of Labelled Compounds and Radiopharmaceuticals published new progress about 17351-62-1. 17351-62-1 belongs to catalysis-chemistry, auxiliary class Salt,Amine, name is Tetrabutylammonium hydrogencarbonate, and the molecular formula is C17H37NO3, COA of Formula: C17H37NO3.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Castillo Melean, Johnny published the artcileEnantiospecific synthesis of 2-[¹⁸F]fluoro-L-phenylalanine and 2-[¹⁸F]fluoro-L-tyrosine by isotopic exchange, Category: catalysis-chemistry, the publication is Organic & Biomolecular Chemistry (2011), 9(3), 765-769, database is CAplus and MEDLINE.

2-[¹⁸F]Fluoro-L-phenylalanine and 2-[¹⁸F]fluoro-L-tyrosine have been developed as promising radiopharmaceuticals for mol. imaging using positron emission tomog. (PET). However, the lack of a convenient radiosynthetic pathway has limited their practical use. In this work a new three-step nucleophilic synthesis of these compounds starting from [¹⁸F]fluoride is described. Corresponding precursors (I) (R¹ = H or OCH₂Ph; Boc = tert-butoxycarbonyl) were ¹⁸F-fluorinated by isotopic exchange, followed by the removal of an activating formyl group with Rh(PPh₃)₃Cl and subsequent hydrolysis of protecting groups in acidic medium. All reactions were carried out using both conventional and microwave heating. Conventional heated reactions yielded the desired products 2-[¹⁸F]Fphe and 2-[¹⁸F]Ftyr in 43% and 49% whereas radiochem. yields of 34% and 43%, resp., were obtained when they were heated by microwaves. Under optimized conditions the enantiomeric purity was ¡Ý94% for both radiopharmaceuticals.

Organic & Biomolecular Chemistry published new progress about 17351-62-1. 17351-62-1 belongs to catalysis-chemistry, auxiliary class Salt,Amine, name is Tetrabutylammonium hydrogencarbonate, and the molecular formula is C17H37NO3, Category: catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Scherner, Cathrin published the artcileA novel route to 6-substituted piperidin-3-ols via domino cyclization of 2-hydroxy-6-phosphinyl-5-hexenyl tosylates with primary amines: synthesis of (¡À)-pseudoconhydrine and (¡À)-epi-pseudoconhydrine, Recommanded Product: Allyldiphenylphosphine oxide, the publication is Synthesis (2014), 46(18), 2506-2514, database is CAplus.

2-Hydroxy-6-phosphinyl-5-hexenyl tosylates, oxirane ring-opening products derived from glycidyl tosylates and phosphinyl- substituted allyl anions, undergo domino S_N2-Michael reactions with primary amines to give 6-phosphinylmethyl piperidin-3-ols. The phosphinyl unit can be used in Horner olefination reactions. This approach is applied to the synthesis of racemic pseudoconhydrine (I) and its epimer II.

Synthesis published new progress about 4141-48-4. 4141-48-4 belongs to catalysis-chemistry, auxiliary class Aryl phosphine ligand,Mono-phosphine Ligands, name is Allyldiphenylphosphine oxide, and the molecular formula is C15H15OP, Recommanded Product: Allyldiphenylphosphine oxide.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Nikoorazm, Mohsen published the artcileFe₃O₄@MCM-41@Zn-Arg: as a novel, magnetically recoverable and ecofriendly nanocatalyst for the synthesis of disulfides, sulfoxides and 2,3-dihydroquinazolin-4(1H)-ones, Formula: C14H10O4S2, the publication is Inorganic and Nano-Metal Chemistry (2021), 51(5), 642-655, database is CAplus.

The direct supporting of Zn-arginine complex on magnetic core-shell nanostructures (Fe₃O₄@MCM-41@Zn-Arg) was reported as a novel, heterogeneous and excellent nanocatalyst, which was applied for the oxidation reaction of sulfides to sulfoxides, oxidative coupling of thiols to their corresponding disulfides and the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives under mild conditions. The simple exptl. procedure, very good catalytic activity, low cost, and excellent recycling are the noteworthy features of the currently employed heterogeneous catalytic system.

Inorganic and Nano-Metal Chemistry published new progress about 119-80-2. 119-80-2 belongs to catalysis-chemistry, auxiliary class sulfides,Carboxylic acid,Benzene, name is 2,2′-Dithiodibenzoic acid, and the molecular formula is C14H10O4S2, Formula: C14H10O4S2.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Marasini, Nirmal published the artcileDevelopment of a hyperbranched polymer-based methotrexate nanomedicine for rheumatoid arthritis, Application of Fmoc-Pro-OH, the publication is Acta Biomaterialia (2022), 298-307, database is CAplus and MEDLINE.

Methotrexate (MTX) is an effective disease modifying anti-rheumatic drug, but can cause significant hepatotoxicity and liver failure in some individuals. The goal of this work was to develop a MTX-conjugated hyperbranched polymeric nanoparticle based on oligo(ethylene glycol) Me ether methacrylate (OEGMA) and examine its ability to selectively deliver MTX to rheumatic joints while sparing the liver. MTX was conjugated to the hyperbranched polymer via a matrix metalloproteinase-13 cleavable peptide linker. Two populations of nanoparticles were produced, with sizes averaging 20 and 200nm. Tri-peptide (FFK)-modified MTX was liberated in the presence of matrix metalloproteinase 13 (MMP-13)and showed 100 to 1000-fold lower antiproliferative capacity in monocytic THP-1 cells compared to unmodified MTX, depending on whether the gamma-carboxylate of MTX was functionalized with O-tert-Bu. Nanoparticles showed prolonged plasma exposure after i.v. injection with a terminal half-life of approx. 1 day, but incomplete (50%) absorption after s.c. administration. Nanoparticles selectively accumulated in inflamed joints in a rat model of rheumatoid arthritis and showed less than 5% biodistribution in the liver after 5 days. MTX-OtBu nanoparticles also showed no hepatocellular toxicity at 500 ¦ÌM MTX equivalent This work provides support for the further development of OEGMA-based hyperbranched polymers as MTX drug delivery systems for rheumatoid arthritis. Nanomedicines containing covalently conjugated methotrexate offer the potential for selective accumulation of the potent hepatotoxic drug in rheumatic joints and limited liver exposure. One limitation of the high surface presentation of methotrexate on a nanoparticle surface, however, is the potential for enhanced liver uptake. We developed several OEGMA-based hyperbranched polymers containing alpha-carboxyl modified and unmodified methotrexate conjugated via an MMP-13 cleavable hexapeptide linker. The modified methotrexate polymer showed promising in vitro and in vivo behavior warranting further development and optimization as an anti-rheumatic nanomedicine. This work presents a new avenue for further research into the development of hyperbranched polymers for rheumatoid arthritis and suggests interesting approaches that may overcome some limitations associated with the translation of anti-rheumatic nanomedicines into patients.

Acta Biomaterialia published new progress about 71989-31-6. 71989-31-6 belongs to catalysis-chemistry, auxiliary class Amino acide derivatives,pyrrolidine, name is Fmoc-Pro-OH, and the molecular formula is C20H19NO4, Application of Fmoc-Pro-OH.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Klingebiel, Uwe published the artcileReactions of lithio-hexamethylcyclotrisilazane with silicon-fluoro compounds, Name: Difluorodiphenylsilane, the publication is Chemische Berichte (1977), 110(4), 1277-83, database is CAplus.

The reaction of lithiocyclotrisilazane I (R = Li with F2SiR1R2 gave 62-95% I (R = SiFR1R2, R1 = F, R2 = F, Me, Ph; R1 = Me, Ph, R2 = Ph; R1 = H, R2 = Me). Similarly, 1,3-dilithio-2,2,4,4,6,6-hexamethylcyclotrisilazane gave corresponding disubstituted derivatives Ring coupling by a Si bridge was achieved by the reaction of SiF-substituted cyclotrisilazanes with LiNHCMe3, or by the reaction of these compounds with two moles of a lithiocyclotrisilazane.

Chemische Berichte published new progress about 312-40-3. 312-40-3 belongs to catalysis-chemistry, auxiliary class Organic Silicones, name is Difluorodiphenylsilane, and the molecular formula is C12H10F2Si, Name: Difluorodiphenylsilane.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia