616-45-5Relevant articles and documents
Comments on 'Unusual oxidative rearrangement of 1,5-diazadecalin'
Winkler, Tammo
, p. 2051 - 2052 (2004)
Oxidation of cis or trans 1,5-diazadecalin with (PhIO)n yields 2-pyrrolidinone and not 1,6-diaza-2,7-cyclodecadione, as reported. This is shown by a comparison of the NMR data of the reaction product with those of 2-pyrrolidinone and 1,6-diaza-2,7-cyclodecadione.
Evolution of catalytic activity driven by structural fusion of icosahedral gold cluster cores
Yang, Dan,Zhu, Yan
, p. 245 - 250 (2021)
Atomically precise gold cluster catalysts have emerged as a new frontier in catalysis science, owing to their unexpected catalytic properties. In this work, we explore the evolution of the catalytic activity of clusters formed by the structural fusion of icosahedral Au13 units, namely Au25(SR)18, Au38(SR)24, and Au25(PPh3)10(SC2H4Ph)5Cl2, in the oxidation of pyrrolidine to γ-butyrolactam. We demonstrate that the structural fusion of icosahedral Au13 units, forming vertex-fused (vf), face-fused (ff), and body-fused (bf) clusters, can induce a decrease in the catalytic activity in the following order: Aubf > Auff > Auvf. The structural fusion of icosahedral Au13 units in the clusters does not distinguish the adsorption modes of pyrrolidine over the three clusters from each other, but modulates the chemical adsorption capacity and electronic properties of the three clusters, which is likely to be the key reason for the observed changes in catalytic reactivity. Our results are expected to be extendable to study and design atomically defined catalysts with elaborate structural patterns, in order to produce desired products.
One-Step Conversion of Glutamic Acid into 2-Pyrrolidone on a Supported Ru Catalyst in a Hydrogen Atmosphere: Remarkable Effect of CO Activation
Suganuma, Satoshi,Otani, Akihiro,Joka, Shota,Asako, Hiroki,Takagi, Rika,Tsuji, Etsushi,Katada, Naonobu
, p. 1381 - 1389 (2019)
Glutamic acid, an abundant nonessential amino acid, was converted into 2-pyrrolidone in the presence of a supported Ru catalyst under a pressurized hydrogen atmosphere. This reaction pathway proceeded through the dehydration of glutamic acid into pyroglutamic acid, subsequent hydrogenation, and the dehydrogenation–decarbonylation of pyroglutaminol into 2-pyrrolidone. In the conversion of pyroglutaminol, Ru/Al2O3 exhibited notably higher activity than supported Pt, Pd, and Rh catalysts. IR analysis revealed that Ru can hydrogenate the formed CO through dehydrogenation–decarbonylation of hydroxymethyl groups in pyroglutaminol and can also easily desorb CH4 from the active sites on Ru. Furthermore, Ru/Al2O3 showed the highest catalytic activity among the tested catalysts in the conversion of pyroglutamic acid. Consequently, the conversion of glutamic acid produced a high yield of 2-pyrrolidone by using the supported Ru catalyst. This is the first report of this one-pot reaction under mild reaction conditions (433 K, 2 MPa H2)? which avoids the degradation of unstable amino acids above 473 K.
An Isolable Terminal Imido Complex of Palladium and Catalytic Implications
Grünwald, Annette,Orth, Nicole,Scheurer, Andreas,Heinemann, Frank W.,P?thig, Alexander,Munz, Dominik
, p. 16228 - 16232 (2018)
Herein, we report the isolation and a reactivity study of the first example of an elusive palladium(II) terminal imido complex. This scaffold is an alleged key intermediate for various catalytic processes, including the amination of C?H bonds. We demonstrate facile nitrene transfer with H?H, C?H, N?H, and O?H bonds and elucidate its role in catalysis. The high reactivity is due to the population of the antibonding highest occupied molecular orbital (HOMO), which results in unique charge separation within the closed-shell imido functionality. Hence, N atom transfer is not necessarily associated with the high valency of the metal (PdIII, PdIV) or the open-shell character of a nitrene as commonly inferred.
Ring size configuration effect and the transannular intrinsic rates in bislactam macrocycles
Guedez, Thanee,Nunez, Andres,Tineo, Evis,Nunez, Oswaldo
, p. 2078 - 2082 (2002)
We have synthesized compounds: N-(2-aminoacetyl)-2-pyrrolidone (1) and N-(2-aminoacetyl)-2-piperidone (2). When these compounds are dissolved in aprotic or protic solvents a fast equilibrium ca. 1:1 between the cyclol form (tetrahedral intermediate) and the bislactam macrocycle is established. The same result has been reported previously for N-(2-aminoacetyl)-2-caprolactam (3). For compounds 2 and 3, dynamic 1H-NMR (using the methylene signals α to the carbonyl and to the amino group) through spectrum simulation has been used to evaluate the exchange between the two mentioned forms at different pH. However, for compound 1 the exchange was evaluated using magnetization transfer technique. The more stable bislactam configuration of the macrocycle form in compounds 2 and 3, is the trans-cis (one lactam with the cyclic alkyl chains trans oriented and the other cis oriented). However, the same form for compound 1 has a more stable cis-cis bislactam configuration. This difference in configuration induces substantial changes in the appearance of the methylene 1H-NMR signals that precludes the use of line-shape analysis to evaluate the rates. The rate law for the proposed mechanism of exchange between the cyclol form and the macrocycle is: K = [macrocycle]/[cyclol] =kobs.f/kobs.r = Kak2[H2O]/[H+]/k-2Kw /[H+] = Kak2[H2O]/k-2Kw; where Ka is the acidity equilibrium constant of the cyclol form, Kw = 10-14 M2 and k2 and k-2 are the second order rate constants for the specific exchange catalysis. Therefore, both, the macrocycle formation (kobs.f) and the cyclol formation (kobs.r) are specific base catalyzed; however the equilibrium constant is independent of pH. Since K is ca. 1, the δG≠ associated with the measured rate constants represent the intrinsic barrier for this non-identical thermoneutral transformation where a cleavage of a tetrahedral intermediate is involved. The activation energies associated with the reverse rate constants then correspond to the intrinsic barrier for transannular cyclolization.
Thermal desorption of covalently bound fullerene C60 from poly-N-vinylpyrrolidone films
Pozdnyakov,Melenevskaya,Ratnikova,Ginzburg
, p. 1965 - 1970 (2003)
Kinetics of formation of thermolysis products in heating of thin films of poly-N-vinylpyrrolidone and of poly-N-vinylpyrrolidone with covalently bound fullerene C60 was studied by thermal desorption mass spectrometry.
Surface ligands enhance the catalytic activity of supported Au nanoparticles for the aerobic α-oxidation of amines to amides
Chatterjee, Puranjan,Kanbur, Uddhav,Manzano, J. Sebastián,Sadow, Aaron D.,Slowing, Igor I.,Wang, Hsin
, p. 1922 - 1933 (2022/04/07)
The catalytic aerobic α-oxidation of amines in water is an atom economic and green alternative to current methods of amide synthesis. The reaction uses O2 as terminal oxidant, avoids hazardous reactants and gives water as the only byproduct. Here we report that the catalytic activity of silica-supported Au nanoparticles for the aerobic α-oxidation of amines can be improved by tethering pyridyl ligands to the support. In contrast, immobilization of thiol groups on the material gives activities comparable to Au supported on bare silica. Our studies indicate that the ligands affect the electronic properties of the Au nanoparticles and thereby determine their ability to activate O2 and mediate C-H cleavage in the amine substrate. The reaction likely proceeds via an Au catalyzed β-hydride elimination enabled by backdonation from electron-rich metal to the orbital. O2, which is also activated on electron-rich Au, acts as a scavenger to remove H from the metal surface and regenerate the active sites. The mechanistic understanding of the catalytic conversion led to a new approach for forming C-C bonds α to the N atoms of amines.
Inhibitors of SARM1
-
, (2022/03/02)
The present disclosure provides compounds and methods useful for inhibiting SARM1 and/or treating and/or preventing axonal degeneration.
An Integrated Cofactor/Co-Product Recycling Cascade for the Biosynthesis of Nylon Monomers from Cycloalkylamines
Sarak, Sharad,Sung, Sihyong,Jeon, Hyunwoo,Patil, Mahesh D.,Khobragade, Taresh P.,Pagar, Amol D.,Dawson, Philip E.,Yun, Hyungdon
, p. 3481 - 3486 (2020/12/17)
We report a highly atom-efficient integrated cofactor/co-product recycling cascade employing cycloalkylamines as multifaceted starting materials for the synthesis of nylon building blocks. Reactions using E. coli whole cells as well as purified enzymes produced excellent conversions ranging from >80 and 95 % into desired ω-amino acids, respectively with varying substrate concentrations. The applicability of this tandem biocatalytic cascade was demonstrated to produce the corresponding lactams by employing engineered biocatalysts. For instance, ?-caprolactam, a valuable polymer building block was synthesized with 75 % conversion from 10 mM cyclohexylamine by employing whole-cell biocatalysts. This cascade could be an alternative for bio-based production of ω-amino acids and corresponding lactam compounds.
En Route to a Heterogeneous Catalytic Direct Peptide Bond Formation by Zr-Based Metal-Organic Framework Catalysts
Conic, Dragan,De Azambuja, Francisco,Harvey, Jeremy N.,Loosen, Alexandra,Parac-Vogt, Tatjana N.,Van Den Besselaar, Maxime
, p. 7647 - 7658 (2021/06/30)
Peptide bond formation is a challenging, environmentally and economically demanding transformation. Catalysis is key to circumvent current bottlenecks. To date, many homogeneous catalysts able to provide synthetically useful methods have been developed, while heterogeneous catalysts remain largely restricted to the studies addressing the prebiotic formation of peptides. Here, the catalytic activity of Zr6-based metal-organic frameworks (Zr-MOFs) toward peptide bond formation is investigated using dipeptide cyclization as a model reaction. Unlike previous catalysts, Zr-MOFs largely tolerate water, and reactions are carried out under ambient conditions. Notably, the catalyst is recyclable and no additives to activate the COOH group are necessary, which are common limitations of previous methods. In addition, a broad reaction scope tolerates substrates with bulky and Lewis basic groups. The reaction mechanism was assessed by detailed mechanistic and computational studies and features a Lewis acid activation of carboxylate groups by Zr centers toward amine addition in which an alkoxy ligand on adjacent Zr sites assists in lowering the barrier of key proton transfers. The proposed concepts were also used to study the formation of intermolecular peptide bond formation. While intrinsic challenges associated with the catalyst structure and water removal limit a more general intermolecular reaction scope under current conditions, the results suggest that further design of Zr-MOF catalysts could render these materials broadly useful as heterogeneous catalysts for this challenging transformation.
