Synthesis and characterization of 2-[(substituted phenyl) methyl]-4-[1,3-dithiolan-2-ylidene]-isoxazolidine-3,5-diones

Abstract

The synthesis of a series of new 2-[(substituted phenyl)methyl]-4-[1,3-dithiolan-2-ylidene]-isoxazolidine-3,5-diones is described for the evaluation of the pesticidal activities. The requisite 1,3-dithiolan-2-ylidene malonyl chloride was prepared by the hydrolysis of the commercially available diisopropyl-1,3-dithiolan-2-ylidene malonate(isoprothiolane), followed by chlorination. The desired product, 2-[(substituted phenyl)methyl]-4-[1,3-dithiolan-2-ylidene]-isoxazolidine-3,5-diones were synthesized by a reaction of appropriate aromatic hydroxylamine and 1,3-dithiolan2-ylidene malonly chloride in the presence of pyridine as catalyst. The aromatic hydroxylamines were prepared by the reaction of aromatic aldehyde with hydroxylamine hydrochloride, followed by reduction with sodium cyanoborohydride. The structure of synthesized products was determined by means of their I.R, $^1H$-NMR, Mass spectra and elemental analysis. The electron-impact(E.I)mass spectra of these compounds at 70 eV showed some novel fragmentation pathway along with general decomposition. It was observed that the parent molecular ion undergoes primarily cleavage of amide C-N bond or N-O bond in the isoxazolidine-3,5-dione ring, followed by oxygen transfer to produce four-membered ring system.