Regioselective synthesis of some isoxazolines and isoxazolidines bearing caprolactam moiety

ABSTRACT

Isoxazoline and isoxazolidine series were obtained by the reactions of aromatic aldonitrones and nitrile oxides with N-vinyl caprolactam via regioselective 1,3-dipolar cycloadditions that yield only 5-caprolactam-substituted regioisomers in moderate yields. The cycloaddition reactions were optimized using different conditions. The utilized one for the transformation of nitrile oxides to isoxazoles is triethylamine at room temperature and the best protocol have been found for the transformation of nitrones to N-methyl isoxazolidines is silver acetate in refluxing xylene. The structural identification of target compounds was established by IR, nuclear magnetic resonance (NMR), high resolution mass spectrometry (HRMS) spectra, and X-ray diffraction analyses.

GRAPHICAL ABSTRACT

KEYWORDS:

• 1,3-Dipolar cycloaddition
• caprolactam
• nitrile oxide
• nitrone

Additional information

Funding

Abant İzzet Baysal University, Directorate of Research Projects Commission (BAP grant no. 2015.03.03.875) are gratefully acknowledged for financial support.