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Organic & Biomolecular Chemistry Feb 2024A palladium-catalyzed borylation of cyclic alkenyl chlorides with Bpin is reported. This transformation allows for the conversion of diverse cyclic alkenyl chlorides...
A palladium-catalyzed borylation of cyclic alkenyl chlorides with Bpin is reported. This transformation allows for the conversion of diverse cyclic alkenyl chlorides into synthetically versatile alkenyl boronates with moderate to excellent yields. The utility of this reaction has been demonstrated with practical Suzuki-Miyaura coupling and aziridination reactions, which allow access to functionalized olefins and valuable boron-substituted aziridines.
PubMed: 38247387
DOI: 10.1039/d3ob01931d -
Organic Letters Jan 2024l-Isovaline biosynthesis by TqaLFM- from was demonstrated . The biochemical analysis of the α-ketoglutarate-dependent oxygenase TqaL- revealed that it produces...
l-Isovaline biosynthesis by TqaLFM- from was demonstrated . The biochemical analysis of the α-ketoglutarate-dependent oxygenase TqaL- revealed that it produces (2,3)-3-ethyl-3-methylaziridine-2-carboxylic acid from l-isoleucine, thus exhibiting a stereoselectivity different from those of the reported homologues. Remarkably, a single mutation on I295 in TqaL- completely exchanged its stereoselectivity to produce the C-3 stereoisomer. TqaFM- generates d-isovaline from (2,3)-aziridine-2-carboxylic acid, suggesting that the stereochemistry of the TqaL product defines that of isovaline.
Topics: Ketoglutaric Acids; Oxygenases; Valine; Aziridines; Stereoisomerism
PubMed: 38227980
DOI: 10.1021/acs.orglett.3c04185 -
Organic Letters Jan 2024A highly diastereoselective [3 + 2] cycloaddition of aziridines with difluorinated silyl enol ethers has been developed. This approach provides a facile methodology for...
A highly diastereoselective [3 + 2] cycloaddition of aziridines with difluorinated silyl enol ethers has been developed. This approach provides a facile methodology for highly functionalized -difluorinated pyrrolidines in good to excellent yields with good functional group tolerance. A one-pot, two-step approach for synthesis of structurally interesting fluorinated pyrroles has also been developed through a cycloaddition/aromatization/desulfonation sequence. Moreover, readily available substrates, mild reaction conditions, and easy scale-up synthesis show practical advantages.
PubMed: 38214536
DOI: 10.1021/acs.orglett.3c04251 -
Journal of the American Chemical Society Jan 2024Chiral aziridines are important structural motifs found in natural products and various target molecules. They serve as versatile building blocks for the synthesis of...
Chiral aziridines are important structural motifs found in natural products and various target molecules. They serve as versatile building blocks for the synthesis of chiral amines. While advances in catalyst design have enabled robust methods for enantioselective aziridination of activated olefins, simple and abundant alkyl-substituted olefins pose a significant challenge. In this work, we introduce a novel approach utilizing a planar chiral rhodium indenyl catalyst to facilitate the enantioselective aziridination of unactivated alkenes. This transformation exhibits a remarkable degree of functional group tolerance and displays excellent chemoselectivity favoring unactivated alkenes over their activated counterparts, delivering a wide range of enantioenriched high-value chiral aziridines. Computational studies unveil a stepwise aziridination mechanism in which alkene migratory insertion plays a central role. This process results in the formation of a strained four-membered metallacycle and serves as both the enantio- and rate-determining steps in the overall reaction.
PubMed: 38170978
DOI: 10.1021/jacs.3c10637 -
Angewandte Chemie (International Ed. in... Feb 2024The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated...
The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated with elemental sulfur in the presence of an organobase, the ring-opening reaction of aziridine with oligosulfide anions occurred, leading to the formation of linear polymers by step-growth polymerization. These newly synthesized polymers possess repeating units containing a sulfonamide or amide functional moiety and oligosulfide bonds with an average sulfur segment of about two. A small molecular model reaction confirmed the nucleophilic addition reaction of elemental sulfur to aziridine. It was verified that S-S dynamic bond exchange takes place in the presence of an organic base within the linear chains. The mixture of the synthesized polysulfides with pyridine exhibits exceptional adhesive properties when applied to steel, and aluminum substrates. Notably, these prepared adhesives displayed good reusability due to the dynamic S-S exchange and complete recyclability due to their solution processability. This elemental sulfur-involved polymerization approach represents an innovative method for the synthesis of advanced sulfur-containing polymers, demonstrating the potential for various applications in adhesives and beyond.
PubMed: 38169090
DOI: 10.1002/anie.202318919 -
Environmental Science and Pollution... Jan 2024In order to reduce the impact of greenhouse gases on the environment, the development of various new CO capture materials has become a hot spot. In this work, a novel...
In order to reduce the impact of greenhouse gases on the environment, the development of various new CO capture materials has become a hot spot. In this work, a novel composite amine solid adsorbent was prepared by simultaneously using tetraethylenepentamine (TEPA) and 2-[2-(dimethylamino) ethoxy] ethanol (DMAEE) for amine functionalization on the polyester microsphere carrier. The introduction of methyl methacrylate (MMA) with high glass transition temperature into the polyester carrier makes the carrier microspheres have high hardness. At the same time, the carrier also contains active epoxy groups and hydrophobic glycidyl methacrylate (GMA, which can undergo ring-opening reaction with composite amines to achieve high-load and low-energy chemical grafting of amines on the carrier. The composite aminated polyester microspheres were used as an efficient adsorbent for CO in simulated flue gas. The results show that the synergistic effect of TEPA-DMAEE composite amine system in the adsorbent is beneficial to the improvement of CO capture capacity. When the total amine content in the impregnating solution is 45 wt% and the composite amine ratio is TEPA: DMAEE = 6: 4, the CO adsorption capacity can reach the optimal value of 2.45 mmol/ g at 70 °C. In addition, the composite amine microsphere adsorbent has cyclic regeneration performance. Importantly, through kinetic fitting, the Avrami kinetic model fits the CO adsorption better than the quasi-first-order and quasi-second-order kinetic models, which proves that physical adsorption and chemical adsorption coexist in the adsorption process. This simple, long-term stable and excellent selective separation performance makes amine-functionalized adsorbents have potential application prospects in CO capture.
Topics: Amines; Carbon Dioxide; Microspheres; Polyesters; Triethylenephosphoramide; Ethyl Ethers; Ethylenediamines
PubMed: 38157164
DOI: 10.1007/s11356-023-31399-3 -
ACS Omega Dec 2023We present a novel approach for the continuous preparation of carbamates. The simple yet fast synthetic route relies on directly utilizing carbon dioxide and, in...
We present a novel approach for the continuous preparation of carbamates. The simple yet fast synthetic route relies on directly utilizing carbon dioxide and, in contrast with the literature-known methods, only employs 1,8-diazabicyclo[5.4.0]undec-7-ene as an additive. The applicable amines' diversity offers considerable flexibility to the synthetic protocol. Additionally, the continuous method's applicability significantly decreases the reaction time typically required for CO-based carbamate synthesis and allows for straightforward and precise gas introduction. The mild reaction conditions and omission of the need for column chromatography render the process less time-demanding and environmentally more benign, providing the desired compounds in yields of 45 to 92%. Moreover, the modified procedure can potentially be applied in the selective synthesis of oxazolidinones from aziridines.
PubMed: 38144084
DOI: 10.1021/acsomega.3c08248 -
Chemical Science Dec 2023Herein, we document the design and development of a novel (3 + 2) cycloaddition reaction aided by the activity of an organic photocatalyst and visible light. The process...
Herein, we document the design and development of a novel (3 + 2) cycloaddition reaction aided by the activity of an organic photocatalyst and visible light. The process is extremely fast, taking place in a few minutes, with virtually complete atom economy. A large variety of structurally diverse aziridines were used as masked ylides in the presence of different types of dipolarophiles (28 examples with up to 94% yield and >95 : 5 dr). Mechanistic insights obtained from photophysical, electrochemical and experimental studies highlight that the chemistry is driven by the generation of the reactive ylide through two consecutive electron-transfer processes. We also report an aerobic cascade process, where an additional oxidation step grants access to a vast array of pyrrole derivatives (19 examples with up to 95% yield). Interestingly, the extended aromatic core exhibits a distinctive absorption and emission profile, which can be easily used to tag the effectiveness of this covalent linkage.
PubMed: 38131079
DOI: 10.1039/d3sc05997a -
Chemistry (Weinheim An Der Bergstrasse,... Feb 2024In recent decades, many efforts have been devoted to studying reactions catalyzed in nanoconfined spaces. The most impressive aspect of catalysis in nanoconfined spaces...
In recent decades, many efforts have been devoted to studying reactions catalyzed in nanoconfined spaces. The most impressive aspect of catalysis in nanoconfined spaces is that the reactivity of the molecules can be smartly driven to disobey classical behavior. A green and efficient three-component aza-Darzens (TCAD) reaction using a catalytic amount of γ-cyclodextrins (CDs) in water has been developed to synthesize N-phenylaziridines. CDs effectively performed this reaction in an environmentally friendly setting, achieving good yields. The same reaction was then performed using polymeric γ-CD such as a γ-cyclodextrin polymer crosslinked (GCDPC) with epichlorohydrin, a sponge-like macroporous γ-cyclodextrin-based cryogel (GCDC), and a γ-cyclodextrin-based hydrogel (GCDH). The homogeneous and heterogeneous catalyst recovery was then studied, and it was proved to be easily recycled several times without relevant activity loss. Water, as a unique and eco-friendly reaction medium, has been utilized for the first time, to the best of our knowledge, in this reaction. The inclusion of the reagents in CDs has been studied and rationalized by NMR spectroscopy experiments and molecular modeling calculations. The credit of the presented protocol includes good yields and catalyst reusability and precludes the use of organic solvents.
PubMed: 38127103
DOI: 10.1002/chem.202303984 -
ChemistryOpen Jun 2024In previous works, we demonstrated that tertiary 3-chloropiperidines are potent chemotherapeutics, alkylating the DNA through the formation of bicyclic aziridinium ions....
In previous works, we demonstrated that tertiary 3-chloropiperidines are potent chemotherapeutics, alkylating the DNA through the formation of bicyclic aziridinium ions. Herein, we report the synthesis of novel secondary 3-chloropiperidine analogues. The synthesis incorporates a new procedure to monochlorinate unsaturated primary amines utilizing N-chlorosuccinimide, while carefully monitoring the temperature to prevent dichlorination. Furthermore, we successfully isolated highly strained bicyclic aziridines by treating the secondary 3-chloropiperidines with a sufficient amount of base. We conclude this work with a DNA cleavage assay as a proof of principle, comparing our previously known substrates to the novel compounds. In this, the secondary 3-chloropiperidine as well as the isolated bicyclic aziridine, proved to be more effective than their tertiary counterpart.
Topics: Piperidines; Antineoplastic Agents, Alkylating; Alkylating Agents; DNA Cleavage; Humans; Aziridines; DNA; Succinimides
PubMed: 38088585
DOI: 10.1002/open.202300181