The fragile intermediates of the domino process leading to an isoxazolidin-5-one, triggered by unique reactivity between Meldrum's acid and an N-benzyl nitrone in the presence of a Brønsted base, were determined thanks to the softness and accuracy of electrospray ionization mass spectrometry coupled to ion mobility spectrometry (ESI-IMS-MS). The combined DFT study shed light on the overall organocatalytic sequence that starts with a stepwise (3+2) annulation reaction that is followed by a decarboxylative protonation sequence encompassing a stereoselective pathway issue.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/chem.201705714 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Construction of benzimidazole- and indole-fused azabicyclo[3.1.0]hexanes bearing a cyano-containing quaternary center from vinylsulfonium salts through sequential [3 + 2]/[2 + 1] cyclization.
Org Biomol Chem
January 2025
Department of Chemistry, College of Sciences, Tianjin University of Science and Technology, Tianjin 300457, People's Republic of China.
A sequential [3 + 2]/[2 + 1] annulation reactions of benzimidazole- and indole-derived acrylonitriles with vinylsulfonium salts have been developed for the first time, and shown to provide in yields of 32 to 98% a series of azabicyclo[3.1.0]hexanes containing each a cyano-substituted tetrasubstituted carbon stereocenter with >20 : 1 dr.
View Article and Find Full Text PDF1,4-Dihydropyrrolo[3,2-]pyrroles with Two Embedded Heptagons via Alkyne Annulation.
J Org Chem
December 2024
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Drastic changes to the character of the acidic catalyst enable the reversal of the double alkyne benzannulation reaction output. In the presence of a strong Brønsted acid, 1,4-dihydropyrrolopyrroles undergo transformation which results in the formation of two 7-membered rings. Computational studies imply that the thermodynamically unfavored 7-membered ring is forged via the kinetically favored attack of a protonated alkyne at the position 3a of pyrrolopyrrole followed by a 1,2-vinyl shift.
View Article and Find Full Text PDFTotal Syntheses of Diepoxy-Kaurane Diterpenoids Enabled by a Bridgehead-Enone-Initiated Intramolecular Cycloaddition.
J Am Chem Soc
December 2024
State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China.
Here, we report the enantioselective total syntheses of four diepoxy--kaurane diterpenoids including (-)-Macrocalin B, (-)-Acetyl-macrocalin B, and (-)-Isoadenolin A and the revised structure of (-)-Phyllostacin I, which hinges on the strategic design of a regioselective and stereospecific trapping of a highly reactive [3.2.1]-bridgehead enone intermediate via a tethered intramolecular Diels-Alder reaction.
View Article and Find Full Text PDFGlycine-Based [3+2] Cycloaddition for the Synthesis of Pyrrolidine-Containing Polycyclic Compounds.
Molecules
December 2024
Center for Green Chemistry, Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125, USA.
The synthesis of pyrrolidine compounds with biological interest is an active research topic. Glycine could be a versatile starting material for making pyrrolidine derivatives. This review covers recent works on glycine-based [3+2] cycloaddition and combines other annulation reactions in the one-pot synthesis of pyrrolidine-containing heterocyclic compounds.
View Article and Find Full Text PDFOrganocatalytic Enantioselective Synthesis of [5.7]-Fused ε-Sultam ,-Heterocycles via (3 + 2)-Annulation of Seven-Membered Cyclic -Sulfonylimines with γ-Hydroxy-α,β-Unsaturated Ketones.
J Org Chem
December 2024
Henan Key Laboratory of Natural Medicine Innovation and Transformation, State Key Laboratory of Antiviral Drugs, Henan University, Kaifeng, Henan 475004, P. R. China.
A highly stereoselective protocol for the (3 + 2)-annulation of biphenyl-bridged seven-membered cyclic -sulfonylimines with γ-hydroxy-α,β-unsaturated ketones was developed. The reactions afforded a wide range of chiral [5.7]-fused ε-sultams bearing N-adjacent 1,3-stereocenters in excellent yields (93-98% yields) and high enantio/diastereoselectivities (up to >99% ee, >20:1 d.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!