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Carbohydrate Research May 2024As the evidence supporting the beneficial effects of human milk oligosaccharides (HMOs) grows, so does the commercial interest in their inclusion in infant formula...
As the evidence supporting the beneficial effects of human milk oligosaccharides (HMOs) grows, so does the commercial interest in their inclusion in infant formula products. This also requires analytical methods capable of their quantification from finished infant formula products as well as from premixed ingredients in some cases. The objective of the present study was the development and single-laboratory validation of a method that can be used for this purpose for seven HMOs: 2'-fucosyllactose (2'FL), 3-fucosyllactose (3FL), difucosyllactose (DFL), 3'-sialyllactose (3'SL), 6'-sialyllactose (6'SL), lacto-N-tetraose (LNT), and lacto-N-neotetraose (LNnT). The present method uses labeling by reductive amination, with 4-aminobenzoic acid ethyl ester (benzocaine) as the labeling reagent and picoline borane as the reducing agent, then applies HPLC separation with UV detection. The seven HMOs could be analyzed from infant formula and premix samples with recoveries between 91 and 108 %, relative standard deviations of 4.3 % or lower across all replicates, and limits of quantitation between 0.001 % and 0.004 % of powder sample by weight. The method was found to be rapid and reliable, with a runtime of only 14 min per injection, in contrast to other methods found in literature which typically use nearly or more than an hour. In addition, it uses instrumentation that's readily available in most analytical laboratories.
PubMed: 38796900
DOI: 10.1016/j.carres.2024.109149 -
Nature Communications May 2024A protocol for trans-hydroboration of indole derivatives using heterogeneous photocatalysis with NHC-borane has been developed, addressing a persistent challenge in...
A protocol for trans-hydroboration of indole derivatives using heterogeneous photocatalysis with NHC-borane has been developed, addressing a persistent challenge in organic synthesis. The protocol, leveraging high crystalline vacancy-engineered polymeric carbon nitride as a catalyst, enables diastereoselective synthesis, expanding substrate scope and complementing existing methods. The approach emphasizes eco-friendliness, cost-effectiveness, and scalability, making it suitable for industrial applications, particularly in renewable energy contexts. The catalyst's superior performance, attributed to its rich carbon-vacancies and well-ordered structure, surpasses more expensive homogeneous alternatives, enhancing viability for large-scale use. This innovation holds promise for synthesizing bioactive compounds and materials relevant to medicinal chemistry and beyond.
PubMed: 38778032
DOI: 10.1038/s41467-024-48769-1 -
RSC Advances May 2024Friedel-Crafts benzylation/alkylation using benzylic, tertiary, and homobenzylic alcohols; aryl aldehydes, aryl ketones, and the highly challenging aryl carboxylic acids...
Friedel-Crafts benzylation/alkylation using benzylic, tertiary, and homobenzylic alcohols; aryl aldehydes, aryl ketones, and the highly challenging aryl carboxylic acids and esters as proelectrophiles has been achieved using borane-ammonia and TiCl, greatly broadening the scope of useable substrates. Incorporation of deactivated aromatic proelectrophiles and specificity for substitution at the benzylic position are demonstrated in the synthesis of various di- and triarylalkane products. Dual protocols allow for the use of standard nucleophilic solvents (benzene, toluene, ) or for stoichiometric addition of more valuable nucleophiles including furans, thiophenes, and benzodioxoles.
PubMed: 38741965
DOI: 10.1039/d4ra02213k -
Nature Communications May 2024In recent years, there has been a growing demand for drug design approaches that incorporate a higher number of sp-hybridized carbons, necessitating the development of...
In recent years, there has been a growing demand for drug design approaches that incorporate a higher number of sp-hybridized carbons, necessitating the development of innovative cross-coupling strategies to reliably introduce aliphatic fragments. Here, we present a powerful approach for the light-mediated B-alkyl Suzuki-Miyaura cross-coupling between alkyl boranes and aryl bromides. Alkyl boranes were easily generated via hydroboration from readily available alkenes, exhibiting excellent regioselectivity and enabling the selective transfer of a diverse range of primary alkyl fragments onto the arene ring under photocatalytic conditions. This methodology eliminates the need for expensive catalytic systems and sensitive organometallic compounds, operating efficiently at room temperature within just 30 min. We further demonstrate the translation of the present protocol to continuous-flow conditions, enhancing scalability, safety, and overall efficiency of the method. This versatile approach offers significant potential for accelerating drug discovery efforts by enabling the introduction of complex aliphatic fragments in a straightforward and reliable manner.
PubMed: 38740738
DOI: 10.1038/s41467-024-48212-5 -
Molecules (Basel, Switzerland) Apr 2024Borane-trimethylamine complex (MeN·BH; BTM) is the most stable of the amine-borane complexes that are commercially available, and it is cost-effective. It is a valuable... (Review)
Review
Borane-trimethylamine complex (MeN·BH; BTM) is the most stable of the amine-borane complexes that are commercially available, and it is cost-effective. It is a valuable reagent in organic chemistry with applications in the reduction of carbonyl groups and carbon-nitrogen double bond reduction, with considerable examples in the reduction of oximes, hydrazones and azines. The transfer hydrogenation of aromatic -heterocycles and the selective -monomethylation of primary anilines are further examples of recent applications, whereas the reduction of nitrobenzenes to anilines and the reductive deprotection of -tritylamines are useful tools in the organic synthesis. Moreover, BTM is the main reagent in the regioselective cleavage of cyclic acetals, a reaction of great importance for carbohydrate chemistry. Recent innovative applications of BTM, such as CO utilization as feedstock and radical chemistry by photocatalysis, have extended their usefulness in new reactions. The present review is focused on the applications of borane-trimethylamine complex as a reagent in organic synthesis and has not been covered in previous reviews regarding amine-borane complexes.
PubMed: 38731507
DOI: 10.3390/molecules29092017 -
Nature Communications May 2024Cheminformatics-based machine learning (ML) has been employed to determine optimal reaction conditions, including catalyst structures, in the field of synthetic...
Cheminformatics-based machine learning (ML) has been employed to determine optimal reaction conditions, including catalyst structures, in the field of synthetic chemistry. However, such ML-focused strategies have remained largely unexplored in the context of catalytic molecular transformations using Lewis-acidic main-group elements, probably due to the absence of a candidate library and effective guidelines (parameters) for the prediction of the activity of main-group elements. Here, the construction of a triarylborane library and its application to an ML-assisted approach for the catalytic reductive alkylation of aniline-derived amino acids and C-terminal-protected peptides with aldehydes and H is reported. A combined theoretical and experimental approach identified the optimal borane, i.e., B(2,3,5,6-Cl-CH)(2,6-F-3,5-(CF)-CH), which exhibits remarkable functional-group compatibility toward aniline derivatives in the presence of 4-methyltetrahydropyran. The present catalytic system generates HO as the sole byproduct.
Topics: Aniline Compounds; Catalysis; Amino Acids; Peptides; Boranes; Hydrogen; Computer Simulation; Oxidation-Reduction; Alkylation; Machine Learning
PubMed: 38714662
DOI: 10.1038/s41467-024-47984-0 -
IScience May 2024Zeolite-encaged metal nanoparticles (NPs) catalysts are emerging as a new frontier owing to their superior ability to stabilize the structure and catalytic performance...
Zeolite-encaged metal nanoparticles (NPs) catalysts are emerging as a new frontier owing to their superior ability to stabilize the structure and catalytic performance in the thermal and environmental catalytic reaction. However, the pore size below 2 nm of the conventional zeolites usually limits the accessibility of metal active sites. Herein, Co-Cu NPs of about 2.5-3.5 nm were uniformly encapsulated in the intracrystalline mesoporous Silicalite-1 (S-1) through alkali-treatment ligand-assisted strategy. The obtained sample (termed CoCu@HS-1) exhibited efficient activity and stability in the ammonia borane hydrolysis with the highest TOF value of 21.46 mol·mol·min. UV-vis DRS spectra indicated that intracrystalline mesopores have greatly improved the openness and accessibility of the active sites, thus improving their catalytic performance. The introduction of Cu regulates the electronic properties of Co, further increasing hydrogen production activity. This research creates new prospects to design other high-performance hierarchical porous zeolite-confined metal/metal oxide catalysts.
PubMed: 38706839
DOI: 10.1016/j.isci.2024.109745 -
Inorganic Chemistry May 2024Molecular heterobimetallic hydride complexes of lanthanide (Ln) and main-group (MG) metals exhibit chemical properties unique from their monometallic counterparts and...
Molecular heterobimetallic hydride complexes of lanthanide (Ln) and main-group (MG) metals exhibit chemical properties unique from their monometallic counterparts and are highly reactive species, making their synthesis and isolation challenging. Herein, molecular Ln/Al heterobimetallic trihydrides [Ln(Tp)(μ-H)Al(H)(N″)] [; Ln = Y, Sm, Dy, Yb; Tp = hydrotris(1-pyrazolyl)borate; N″ = N(SiMe)] have been synthesized by facile insertion of aminoalane [MeN·AlH] into the Ln-N amide bonds of [Ln(Tp)(N″)] (). Thus, this is a simple synthetic strategy to access a range of Ln/Al hydrides. Reactivity studies demonstrate that is a heterobimetallic hydride, with evidence for the cooperative nature of shown by the catalytic amine-borane dehydrocoupling under ambient conditions in contrast to its monomeric counterparts.
PubMed: 38682828
DOI: 10.1021/acs.inorgchem.4c00824 -
Molecules (Basel, Switzerland) Apr 2024Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted...
Graphene is a good support for immobilizing catalysts, due to its large theoretical specific surface area and high electric conductivity. Solid chemical converted graphene, in a form with multiple layers, decreases the practical specific surface area. Building pores in graphene can increase specific surface area and provide anchor sites for catalysts. In this study, we have prepared porous graphene (PG) via the process of equilibrium precipitation followed by carbothermal reduction of ZnO. During the equilibrium precipitation process, hydrolyzed N,N-dimethylformamide sluggishly generates hydroxyl groups which transform Zn into amorphous ZnO nanodots anchored on reduced graphene oxide. After carbothermal reduction of zinc oxide, micropores are formed in PG. When the Zn feeding amount is 0.12 mmol, the average size of the Pt nanoparticles on PG in the catalyst is 7.25 nm. The resulting Pt/PG exhibited the highest turnover frequency of 511.6 min for ammonia borane hydrolysis, which is 2.43 times that for Pt on graphene without the addition of Zn. Therefore, PG treated via equilibrium precipitation and subsequent carbothermal reduction can serve as an effective support for the catalytic hydrolysis of ammonia borane.
PubMed: 38675581
DOI: 10.3390/molecules29081761 -
International Journal of Molecular... Apr 2024A series of bench-stable Co(II) complexes containing hydrazone Schiff base ligands were evaluated in terms of their activity and selectivity in carbon-carbon multiple...
A series of bench-stable Co(II) complexes containing hydrazone Schiff base ligands were evaluated in terms of their activity and selectivity in carbon-carbon multiple bond transfer hydrogenation. These cobalt complexes, especially a Co(II) precatalyst bearing pyridine-2-yl-N(Me)N=C-(1-methyl)imidazole-2-yl ligand, activated by LiHBEt, were successfully used in the transfer hydrogenation of substituted styrenes and phenylacetylenes with ammonia borane as a hydrogen source. Key advantages of the reported catalytic system include mild reaction conditions, high selectivity and tolerance to functional groups of substrates.
Topics: Hydrogenation; Cobalt; Schiff Bases; Catalysis; Boranes; Coordination Complexes; Alkynes; Ammonia; Molecular Structure
PubMed: 38673948
DOI: 10.3390/ijms25084363