A novel and efficient iron-catalyzed cycloaddition reaction using readily available 2,3-diaryl-2-azirines and primary amides is reported. A wide range of trisubstituted oxazoles could be achieved in good yields with good functional group compatibility. In this transformation, two C-N bonds were cleaed and new C-N and C-O bonds were formed.
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http://dx.doi.org/10.1021/acs.joc.0c02843 | DOI Listing |
J Am Chem Soc
April 2024
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Redox-active pyridine(diimine) (PDI) iron catalysts promote the reversible [2 + 2] cycloaddition of alkenes and dienes to cyclobutane derivatives that have applications ranging from fuels to chemically recyclable polymers. Metallacycles were identified as key intermediates, and spin crossover from the singlet to the triplet surface was calculated to facilitate the reductive coupling step responsible for the formation of the four-membered ring. In this work, a series of sterically and electronically differentiated PDI ligands was studied for the [2 + 2] cycloaddition of ethylene and butadiene to vinylcyclobutane.
View Article and Find Full Text PDFNat Commun
March 2024
State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, 100050, Beijing, P. R. China.
The Ganoderma meroterpenoids are a growing class of natural products with architectural complexity, and exhibit a wide range of biological activities. Here, we report an enantioselective total synthesis of the Ganoderma meroterpenoid (‒)-lucidumone. The synthetic route features several key transformations, including a) a Cu-catalyzed enantioselective silicon-tethered intramolecular Diels-Alder cycloaddition to construct the highly functionalized bicyclo[2.
View Article and Find Full Text PDFChemistry
April 2024
PSL University, Chimie ParisTech, CNRS UMR 8060, Institute of Chemistry for Life and Health Sciences, CSB2D Team, 75005, Paris, France.
We report an efficient iron-catalyzed cycloaddition procedure leading to the construction of (hetero)aromatic rings by alkyne [2+2+2] cycloisomerization. This method relies on the use of an air-stable (N,N)Fe(II) precursor easily prepared from a commercially available ligand derived from 1,10-phenanthroline, reduced in situ into a catalytically active non-innocent (N,N ⋅)Fe(II) species. This system displays a large scope application, operates under mild conditions and at low catalytic charges (25 cycloadducts formed, up to 1.
View Article and Find Full Text PDFOrg Lett
September 2023
Laboratory of Catalysis and Organic Synthesis, Institut des Sciences et Ingénierie Chimique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
An iron-catalyzed alkylazidation of dehydroamino acids using peroxides as alkyl radical precursors is described. Non-natural azidated amino esters bearing an α-alkyl chain could be obtained in 18-94% yields using TMSN as an azide source. The obtained α-alkyl-α-azide α-amino esters could be further functionalized through cycloaddition or azide reduction with amide couplings to afford aminal-type peptides, α-triazolo amino acids, and tetrahydro-triazolopyridine, showing the great versatility of this now easily accessible class of amino acids.
View Article and Find Full Text PDFJ Org Chem
January 2023
Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, P. R. China.
The mechanism of iron-catalyzed intramolecular [2 + 2] cycloaddition and cycloisomerization of enyne acetates has been investigated with DFT computations. Both mechanisms start the catalytic cycle from the stepwise 1,2-acyloxy migration to afford the iron carbene. The [2 + 2] cycloaddition mechanism involves subsequent key steps of [2 + 2] cycloaddition, 1,2-acyloxy migration, and reductive elimination to generate the azabicyclo [3.
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