Nitrone

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The basic structure of nitrones. R 1 , R 2 and R 3 are organyl radicals or hydrogen atoms (with the exception of R 3 ).

Nitrones are a group of chemical compounds in organic chemistry. They contain a functional group that can be described as the N - oxide of an imine . Due to their hybrid charge, nitrones are relatively reactive, for example as a 1,3-dipole in additions to electron-rich CC multiple bonds.

presentation

Nitrones can be produced by the reaction of ketones or dienes with two consecutive double bonds with N -monoalkylated hydroxylamines . At first there is a nucleophilic attack of the nitrogen on the carbon of the carbonyl , an intermediate product with positively charged tetravalent nitrogen and negatively charged oxygen on the former carbonyl is formed. After elimination of water with the former oxygen of the carbonyl and the two hydrogen atoms of the hydroxyamine, the nitrone structure is obtained through the formation of a double bond between nitrogen and carbon.

Another possibility is the dehydrogenation of a disubstituted alkyl-substituted hydroxyamine. The N -alkylation of oximes and the oxidative dehydrogenation of secondary amines also lead to the nitrones.

Depiction of the nitrone

Reactions

Nitrones react with alkenes to form isoxazolidines. This 1,3-dipolar cycloaddition is strictly cis-selective. Isoxazolidines can be split into β-amino alcohols by catalytic hydrogenation.

Nitrones react with terminal alkynes in the presence of copper (I) iodide to form β-lactams, which are difficult to access . This reaction is also known as the Kinugasa reaction .

Reactions of the nitrones

Individual evidence

  1. ↑ Entry on nitrones . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.N04164 Version: 2.3.3.
  2. ^ Ian Fleming: Frontier orbitals and reactions of organic compounds. Wiley-VCH, Weinheim 1988, ISBN 3-527-25792-6 , p. 174.
  3. ^ A b D. Döpp, H. Döpp In: D. Klamann (Ed.): Methods of Organic Chemistry. Vol. E14b, Thieme Verlag, Stuttgart 1990, ISBN 3-13-220004-2 , pp. 1372-1544.
  4. ↑ Manabu Kinugasa, Shizunobu Hashimoto: The reactions of copper (I) phenylacetylide with nitrones. In: J. Chem. Soc., Chem. Commun. 1972, pp. 466-467, doi: 10.1039 / C39720000466 .
  5. ↑ Runa Pal, Amit Basak: A novel synthesis of -lactam fused cyclic enediynes by intramolecular Kinugasa reaction. In: Chem. Commun. 2006, pp. 2992-2994, doi: 10.1039 / b605743h .
  6. ^ Ryo Shintani, Gregory C. Fu : Catalytic Enantioselective Synthesis of β-Lactams: Intramolecular Kinugasa Reactions and Interception of an Intermediate in the Reaction Cascade. In: Angew. Chem. Int. Ed. 2003, 42, pp. 4082-4085, doi: 10.1002 / anie.200352103 .