Nitrone

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File:Nitrone-general-structure-2D.png
General structure of a nitrone

A nitrone is the N-oxide of an imine and a functional group in organic chemistry. The general structure is R1R2C=NR3+O-.

A nitrone is 1,3-dipole in 1,3-dipolar cycloadditions. It reacts with alkenes to an isoxazolidine:

Nitrone cycloadditions

One example of this reaction type is the reaction of various Baylis-Hillman adducts with C-Phenyl-N-methylnitrone forming an isoxazolidine in which R1 is phenyl, R2 is hydrogen and R3 is a methyl group [1].

Nitrones react with terminal alkynes and a copper salt to beta-lactam. This reaction is also called the The Kinugasa reaction [2] for example in this reaction: [3]:

The first step in this reaction is a dipolar cycloaddition of the nitrone with the in situ generated copper(I) acetylide to a 5-membered ring structure which rearranges in the second step.


References

  1. Diastereoselectivity of Nitrone 1,3-Dipolar Cycloaddition to Baylis-Hillman Adducts Branislav Dugovič, Lubor Fišera, Christian Hametner and Nada Prónayovác. Arkivoc 2004 BS-834A Article
  2. The reactions of copper(I) phenylacetylide with nitrones Manabu Kinugasa and Shizunobu Hashimoto J. Chem. Soc., Chem. Commun., 1972, 466 - 467, doi:10.1039/C39720000466
  3. A novel synthesis of -lactam fused cyclic enediynes by intramolecular Kinugasa reaction Runa Pal and Amit Basak Chem. Commun., 2006, 2992 - 2994, doi:10.1039/b605743h



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