1,720,964 research outputs found
Synthesis of Nitrogen-Containing Heterocyclic Scaffolds through Sequential Reactions of Aminoalkynes with Carbonyls
Full text linkSequential reactions of aminoalkynes represent a powerful tool to easily assembly biologically important polyfunctionalized nitrogen heterocyclic scaffolds. Metal catalysis often plays a key role in terms of selectivity, efficiency, atom economy, and green chemistry of these sequential approaches. This review examines the existing literature on the applications of reactions of aminoalkynes with carbonyls, which are emerging for their synthetic potential. Aspects concerning the features of the starting reagents, the catalytic systems, alternative reaction conditions, pathways and possible intermediates are provided
Friedländer-Type Reaction of 4-Cholesten-3-one with 2′-Aminoacetophenone: Angular versus Linear Quinoline-Fused Steroids
Full text linkTo optimize the experimental conditions used for the Friedländer-type condensation, an angular fused 4-substituted quinoline steroid has been obtained in very high yield and regioselectivity using readily available 4-cholesten-3-one and 2′-aminoacetophenone. Moreover, by varying the reaction conditions and the catalyst, the corresponding linear regioisomer was also achieved with an acceptable isolated yield and high chemoselectivity. Both structures have been definitively elucidated via 2D-NMR and fully characterized
Electrochemical-Induced Cascade Reaction of 2-Formyl Benzonitrile with Anilines: Synthesis of N-Aryl Isoindolinones
No full textAn electrochemical initiated tandem reaction of anilines with 2-formyl benzonitrile has been developed. Thus, unprecedented 3-N-aryl substituted isoindolinones have been conveniently achieved by constant current electrolysis in a divided cell using catalytic amount of electricity and supporting electrolyte and a Pt-cathode as working electrode. The origin of the electrochemical activation as well as the mechanism of the subsequent chemical cascade reactions have been investigated by DFT calculations
Unrevealing the Nitrogen Elusive Chirality of 3-Sulfanyl and 3-Sulfinyl N-Tosyl Isoindolinones by ECD Spectra: an Experimental and Theoretical Investigation
No full textThe nitrogen–hybridization/pyramidalization of two solvated N-tosylisoindolinone derivatives having chiral residues in adjacent (I) or adjacent and distal (II) position has been investigated by a theoretical-computational procedure based on Molecular Dynamics simulations and Quantum–Chemical calculations. After validation of our methodology in providing a reliable repertory of conformations by modeling the electronic circular dichroism (EDC) spectra, the electronic features associated with N-pyramidalization were further characterized through Natural Bond Order (NBO) analysis. Comparing against the N-geometry observed in crystal structures as a reference, our findings reveal that the presence of neighbouring chiral centers induces a more pronounced N-pyramidalization in solution than in the solid state, both in I and II. Furthermore, NBO analysis confirms that the N-lactam mostly retains the sp2 character but exhibits slight configurational distortion (ξI=13°; ξII=21°), which significantly influences the chiroptical activities observed in ECD spectra of I and II. This substantiates the N-lactams as configurationally stable chiral centers
Electrocatalytic Hydrogen Evolution Reaction Enabling Cyanation of Electron-poor Carbons with Acetone Cyanohydrin
Full text linkThe Pt-cathode hydrogen evolution reaction (Pt-HER) of acetone cyanohydrin provides an alternative method for introducing the cyano group onto electrophilic carbons of imines and chalcones. The synthesis of α-aminonitriles and β-cyano ketones has been achieved smoothly with a small excess of cyanating agent (2 equivalent), catalytic amount of supporting electrolyte and low electricity consumption (0.02 F/mol). Besides demonstrating a general atom economy, the high Faradaic efficiency, allows for a scale-up with low-demanding electrochemical design and short electrolysis times
Friedländer-Type Reaction of 4-Cholesten-3-one with 2′-Aminoacetophenone: Angular versus Linear Quinoline-Fused Steroids
No full textTo optimize the experimental conditions used for the Friedländer-type condensation, an angular fused 4-substituted quinoline steroid has been obtained in very high yield and regioselectivity using readily available 4-cholesten-3-one and 2′-aminoacetophenone. Moreover, by varying the reaction conditions and the catalyst, the corresponding linear regioisomer was also achieved with an acceptable isolated yield and high chemoselectivity. Both structures have been definitively elucidated via 2D-NMR and fully characterized
Gold Salts as Alternative Catalysts in Promoting Cascade Condensation of 2-Aminobenzaldehydes with Alcohols and Amines
No full textThe distinctive features of gold self-relay catalysts were alternatively utilized in the intriguing cascade condensation of 2-aminobenzaldehydes with alcohols and amines. Using NaAuCl4·2H2O as a catalyst, a range of 13-alkyloxy-7,11b-dihydro-6H,13H-6,12-[1,2]benzenoquinazolino[3,4-a]quinazoline derivatives was produced in good to high yields through A3B condensation of various 2-aminobenzaldehydes with alcohols. By carefully choosing the reaction conditions, gold catalysis also proved effective for A2B condensation with primary aryl- and benzylamines, facilitating the synthesis of challenging McGeachin bisaminals, including a chiral nonracemic derivative of 2-(S)-methylbenzylamine. The mild conditions of this gold-catalyzed approach may lead to new advancements in the field
On Route to Diverse Nitrogen-Bridged Polyhetero-cycles with an N(acyl), N(aryl)-acetal Core
No full textAn expeditious assembling of fused poly-heterocyclic structures having a N(Acyl), N(aryl)-Acetal core has been accomplished by cascade reaction of ortho-functionalized anilines with 2-formylbenzonitrile and subsequent intramolecular N-amidic cyclization on different electrophilic carbons. The syntheses have been finalized using both cathodically-initiated and conventional base-catalyzed methods and comparing the two approaches in terms of substrate/product scope, efficiency, energy-saving and sustainability in general
Ethyl 2-(12-Oxo-10,12-dihydroisoindolo[1,2-b] Quinazolin-10-yl) Acetate
No full textThe title compound has been synthetized using a one-pot cascade process of ethyl (E)-3-(2-aminophenyl) acrylate and 2-formylbenzonitrile in the presence of Cs2CO3 as the catalyst. The synthetic route has been rationalized as a base-catalyzed tandem addition/cyclization/rearrangement initiated by the aniline molecule, followed by sequential aza-Michael addition/dehydrogenation. A theoretical investigation also provided a rationale for its fluorescence properties
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