64-04-0Relevant articles and documents
Mesoporous Metal–Metalloid Amorphous Alloys: The First Synthesis of Open 3D Mesoporous Ni-B Amorphous Alloy Spheres via a Dual Chemical Reduction Method
Kang, Yunqing,Henzie, Joel,Gu, Huajun,Na, Jongbeom,Fatehmulla, Amanullah,Shamsan, Belqes Saeed A.,Aldhafiri, Abdullah M.,Farooq, W. Aslam,Bando, Yoshio,Asahi, Toru,Jiang, Bo,Li, Hexing,Yamauchi, Yusuke
, (2020)
Selective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal–boron alloys have a tunable, glass-like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel–boron (Ni-B) alloy is reported. The hydrogenation of benzyl cyanide to β-phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni-B alloy spheres have a turnover frequency value of 11.6 h?1, which outperforms non-porous Ni-B spheres with the same composition. The bottom-up synthesis of mesoporous transition metal–metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth-abundant catalysts.
Self-Immolative Hydroxybenzylamine Linkers for Traceless Protein Modification
Rose, Douglas A.,Treacy, Joseph W.,Yang, Zhongyue J.,Ko, Jeong Hoon,Houk,Maynard, Heather D.
supporting information, p. 6050 - 6058 (2022/04/12)
Traceless self-immolative linkers are widely used for the reversible modification of proteins and peptides. This article describes a new class of traceless linkers based on ortho- or para-hydroxybenzylamines. The introduction of electron-donating substituents on the aromatic core stabilizes the quinone methide intermediate, thus providing a platform for payload release that can be modulated. To determine the extent to which the electronics affect the rate of release, we prepared a small library of hydroxybenzylamine linkers with varied electronics in the aromatic core, resulting in half-lives ranging from 20 to 144 h. Optimization of the linker design was carried out with mechanistic insights from density functional theory (DFT) and the in silico design of an intramolecular trapping agent through the use of DFT and intramolecular distortion energy calculations. This resulted in the development of a faster self-immolative linker with a half-life of 4.6 h. To demonstrate their effectiveness as traceless linkers for bioconjugation, reversible protein-polyethylene glycol conjugates with a model protein lysozyme were prepared, which had reduced protein activity but recovered ≥94% activity upon traceless release of the polymer. This new class of linkers with tunable release rates expands the traceless linkers toolbox for a variety of bioconjugation applications.
Metal-Free Deoxygenation of Chiral Nitroalkanes: An Easy Entry to α-Substituted Enantiomerically Enriched Nitriles
Pirola, Margherita,Faverio, Chiara,Orlandi, Manuel,Benaglia, Maurizio
supporting information, p. 10247 - 10250 (2021/06/18)
A metal-free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β-cyano esters, α-aryl alkylnitriles, and TBS-protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine).
Direct Conversion of Hydrazones to Amines using Transaminases
Carter, Eve M.,Hailes, Helen C.,Sheppard, Tom D.,Subrizi, Fabiana,Ward, John M.
, p. 4520 - 4523 (2021/09/20)
Transaminase enzymes (TAms) have been widely used for the amination of aldehydes and ketones, often resulting in optically pure products. In this work, transaminases were directly reacted with hydrazones in a novel approach to form amine products. Several substrates were investigated, including those with furan and phenyl moieties. It was determined that the amine yields increased when an additional electrophile was added to the reaction mixture, suggesting that they can sequester the hydrazine released in the reaction. Pyridoxal 5’-phosphate (PLP), a cofactor for transaminases, and polyethylene glycol (PEG)-aldehydes were both found to increase the yield of amine formed. Notably, the amination of (S)-(?)-1-amino-2-(methoxymethyl)pyrrolidine (SAMP) hydrazones gave promising results as a method to form chiral β-substituted amines in good yield.