Collect. Czech. Chem. Commun. 2008, 73, 649-656

Regioselectivity of [2+3] Cycloaddition of Triphenylnitrone to Nitroethene - AM1/COSMO Computational Study

Radomir Jasiński* and Andrzej Barański

Institute of Organic Chemistry and Technology, Cracow University of Technology, ul. Warszawska 24, 31-155 Cracow, Poland


Two isomeric pathways for the [2+3] cycloaddition of triphenylnitrone to nitroethene in a dielectric medium corresponding to the relative permittivity of toluene was evaluated in therms of AM1/COSMO calculations. It was found that reaction leading to 4-nitro-2,3,3-triphenylisoxazolidine (path A) occurs via a zwitterionic intermediate, whereas the reaction leading to 5-nitro-2,3,3-triphenylisoxazolidine (path B) takes place in concerted way. The activation parameters estimated for both reaction pathways indicate that A is favored (∆GTSA = 34.33 kcal/mol; ∆GTSB = 43.37 kcal/mol). The reaction regioselectivity is in good agreement with the experimental data.

Keywords: [2+3] Cycloaddition; Nitrone; Nitroethene; Regioselectivity; Mechanism; AM1/COSMO calculations.

References: 21 live references.