87372-49-4

Upstream product

• 17537-31-4 Acetophenone-methyl-d3 
• 98-86-2 acetophenone 
• 70-11-1 α-bromoacetophenone 

Downstream Products

• 103873-01-4 C₁₂H₉⁽²⁾H₄NO₂ 
• 88073-12-5 ethyl <ω-(2)H2>phenacyloxycarbamate 
• 1231941-73-3 C₁₅H₁₇⁽²⁾HO₃ 
• 1420296-01-0 2-phenylquinoxaline 
• 10225-37-3 2,2-dideuterio-1,3-diphenyl-propane-1,3-dione 
• 66255-92-3 rac-(β,β-²H₂)styrene oxide 

Relevant academic research and scientific papers

Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions

Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.

Synthesis of Cyclic Organic Carbonates Using Atmospheric Pressure CO2 and Charge-Containing Thiourea Catalysts

Cycloadditions of epoxides with CO2 to synthesize cyclic five-membered ring organic carbonates are of broad interest from a synthetic, environmental, and green chemistry perspective, and the development of effective catalysts for these transformations is an ongoing challenge. A series of eight charge-containing thiourea salts that catalyze these reactions under mild conditions (i.e., 60 °C and atmospheric CO2 pressure) are reported. Substrate scope and mechanistic studies were also carried out, isotope effects were measured, and a reactive intermediate was isolated revealing a surprising pathway in which a thiourea catalyst serves as a nucleophile in the cleavage of the epoxide ring.

Transition-metal-free formal decarboxylative coupling of ?±-oxocarboxylates with ?±-bromoketones under neutral conditions: A simple access to 1,3-diketones

A transition-metal-free formal decarboxylative coupling reaction between ?±-oxocarboxylates and ?±-bromoketones to synthesize 1,3-diketone derivatives is presented. In this reaction, a broad scope of substrates can be employed, and neither a metal-based reagent nor an additional base is required. DFT calculations reveal that this reaction proceeds through a coupling followed by decarboxylation mechanism and the ?±-bromoketone unprecedentedly serves as a nucleophile under neutral conditions. The rate-determining step is an unusual hydrogen-bond-assisted enolate formation by thermolysis.

Vinyl dihydropyrans and dihydrooxazines: Cyclizations of catalytic ruthenium carbenes derived from alkynals and alkynones

A novel synthesis of 2-vinyldihydropyrans and dihydro-1,4-oxazines (morpholine derivatives) from alkynals and alkynones has been developed. The cyclizations require a mild generation of catalytic ruthenium carbenes from terminal alkynes and (trimethylsilyl)diazomethane followed by trapping with carbonyl nucleophiles. Mechanistic aspects of the new cyclizations are discussed. Setting a trap: A novel synthesis of 2-vinyldihydropyrans and dihydro-1,4-oxazines (morpholine derivatives) from alkynals and alkynones has been developed. The cyclizations require a mild generation of catalytic ruthenium carbenes from terminal alkynes and (trimethylsilyl)diazomethane followed by trapping with carbonyl nucleophiles.

Multifold bond cleavage and formation between meoh and quinoxalines (or benzothiazoles): Synthesis of carbaldehyde dimethyl acetals

A K2S2O8-mediated direct cross-coupling of quinoxalines (or benzothiazoles) with methanol leading to 2-quinoxalinyl (or 2-benzothiazolyl) carbaldehyde dimethyl acetals has been achieved. 2-Quinoxalinyl carbaldehyde dimethyl acetals were readily converted into 2-quinoxalinyl carbaldehydes in good to excellent yields under acidic conditions. Preliminary mechanistic studies suggest that the reaction proceeds via multifold bond cleavage and formation between methanol and N-heterocycles involving a dioxygen-participated radical process. This method allows for the synthesis of a variety of 2-quinoxalinyl (or 2-benzothiazolyl) carbaldehyde dimethyl acetals directly via cross-coupling of simple N-heterocyclic C-H bond and methanol under aldehyde-, acid-, and transition-metal-free conditions.

On the mechanism of ylide-mediated cyclopropanations: Evidence for a proton-transfer step and its effect on stereoselectivity

In this paper, we describe studies on the cyclopropanation of Michael acceptors with chiral sulfur ylides. It had previously been found that semi-stabilized sulfonium ylides (e.g., Ph-stabilized) reacted with cyclic and acyclic enones and substituted acrylates with high ee and that stabilized sulfonium ylides (e.g., ester-stabilized) reacted with cyclic enones again with high ee. The current study has focused on the reactions of stabilized sulfonium ylides with acyclic enones which unexpectedly gave low ee. Furthermore, a clear correlation of ee with ylide stability was observed in reactions with methyl vinyl ketone (MVK): ketone-stabilized ylide gave 25% ee, ester-stabilized ylide gave 46% ee, and amide-stabilized ylide gave 89% ee. It is believed that following betaine formation an unusual proton transfer step intervenes which compromises the enantioselectivity of the process. Thus, following addition of a stabilized ylide to the Michael acceptor, rapid and reversible intramolecular proton transfer within the betaine intermediate, prior to ring closure, results in an erosion of ee. Proton transfer occurred to the greatest extent with the most stabilized ylide (ketone). When the same reactions were carried out with deuterium-labeled sulfonium ylides, higher ees were observed in all cases since proton/deuteron transfer was slowed down. The competing proton transfer or direct ring-closure pathways that are open to the betaine intermediate apply not only to all sulfur ylides but potentially to all ylides. By applying this model to S-, N-, and P-ylides we have been able to rationalize the outcome of different ylide reactions bearing a variety of substituents in terms of chemo- and enantioselectivity.

Cis/trans Stereochemical Effects in the Negative Chemical Ionization/OH- Mass Spectra of Strained-Ring Azabicycloalkanes Using MIKE and CA/MIKE Spectrometry

Stereospecific decomposition reactions of isomeric (cis and trans) deprotonated molecules from azabicycloalkane derivatives as azetidinols generated under negative chemical ionization (NCI)/OH- have been examined using mass-analysed ion kinetic energy (MIKE) and collision activation (CI)/MIKE spectra.These measurements together with the ones obtained on specifically labelled compounds enabled us to determine the origin of the stereochemical effects.The results indicate that the hydroxylic proton constitutes the preferential (ca. 90percent) site for the deprotonation process.Subsequent fragmentations of the deprotonated species observed in the second field-free region of a reversed geometry instrument are affected by the stereochemistry of the hydroxylic group.The isomer with the hydroxyl group in the cis position relative to the hydrogen at the ring junction mainly loses H2O, while the trans isomer eliminates CH3*, both processes occurring with high specificity.Labelling studies indicate that two major pathways exist for the elimination of H2O from the cis isomer and the loss of CH3* from the trans isomer.The course of the reaction is determined by the ability of the stereoisomers to transfer a proton during the first decomposition step.When the size of the lactam ring is increased from a five-membered ring to a six- or seven-membered ring, these stereochemical effects tend to become less pronounced.