Synthesis of 2,2,4-trisubstituted 2H-1,3-oxazetes from acyl isothiocyanates

Abstract

Reaction of acyl isothiocyanates with amines, methanol or methanethiol afforded addition products which on treatment with lithium hydride in dimethylformamide and subsequent alkylation with methyl iodide, cyclized immediately to give 2,2,4-trisubstituted 2H-1,3-oxazetes which represent a new type of heterocycles. Under identical conditions, N-phenyl-N'-cinnamoylthioureas and N-phenyl-N'-3-(2-furyl)-acryloylthioureas afforded S-methyl N-acylmonothiocarbamates whereas N-phenyl-N'-acetylthiourea gave N-phenyl-N'-acetyl-S-methylisothiourea. The structure of the obtained compounds was confirmed by their IR, 1H NMR and mass spectra.