A facile synthetic method for preparation of bicyclo[4.2.0] nitrogen heterocycles has been developed via a thermal induced intramolecular [2 + 2] cycloaddition reaction of allene-ACPs. The DFT calculations indicate that this intramolecular cycloaddition proceeds in a concerted manner and a strained small ring is essential.
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http://dx.doi.org/10.1039/c3ob40911b | DOI Listing |
J Org Chem
January 2025
School of Chemistry, University of Hyderabad, C. R. Rao Road, Gachibowli, Hyderabad 500 046, India.
A facile two-step enantiospecific synthesis of 5,6,7,8-tetrahydroindolizine scaffolds has been developed via TMSOTf-promoted [3 + 2] cycloaddition between carbohydrate-derived spirocyclic donor-acceptor cyclopropanecarboxlates and alkyl/aryl nitriles followed by an intramolecular Mitsunobu reaction of the resulting chiral 2/5-(4-hydroxybutyl)pyrrole derivatives.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
A concise and convergent synthesis of the isosteroidal alkaloids veratramine and 20--veratramine has been accomplished. A Horner-Wadsworth-Emmons olefination joins two chiral building blocks of approximately equal complexity and a transition-metal catalyzed intramolecular Diels-Alder cycloaddition-aromatization cascade constructs the tetrasubstituted arene. Other key steps include a highly diastereoselective crotylation of an -sulfonyl iminium ion and an Eschenmoser fragmentation.
View Article and Find Full Text PDFChemphyschem
January 2025
Durgapur Government College, Department of Chemistry, INDIA.
The relative reactivity and cis/trans selectivity of the intramolecular [3+2] cycloaddition (IM32CA) reactions of nitrile oxide (NO), azide (AZ), nitrile sulfide (NS) and nitrile ylide (NY), leading to functionalized heterocycles are studied within the Molecular Electron Density Theory. The kinetically controlled IM32CA reactions are predicted to be cis stereospecific, while the reaction feasibility follows the order NY > NS > NO > AZ with the respective activation Gibbs free energies of 13.7, 17.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Nankai University, College of Chemistry, 94 Weijin Rd., 300071, Tianjin, CHINA.
Reliable methods for rapidly constructing C(sp3)-rich three-dimensional polycycles are in high demand for organic synthesis and medicinal chemistry. Although there are various mature systems for synthesizing five- or six-membered polycycles, a catalytic platform for accessing diverse cycloheptanoid-containing polycyclic scaffolds is lacking. Herein, we describe a method for copper-catalyzed intramolecular 2-aminoallyl cation-diene (4 + 3) cycloaddition reactions.
View Article and Find Full Text PDFChem Sci
December 2024
Department of Chemistry, State Key Laboratory of Synthetic Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
Phosphorescent gold(iii) complexes possess long-lived emissive excited states, making them ideal for use as molecular sensors and photosensitizers for organic transformations. Literature reports indicate that gold(iii) emitters exhibit good catalytic activity in homogeneous photochemical reactions. Heterogeneous metal-organic framework (MOF)-supported gold(iii) photocatalysts are considered to show high recyclability in photochemical reactions and potentially provide new selectivities.
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