Ureas from Lossen Rearrangements of Hydroxamic Acids Induced by p-Toluenesulfonyl Chloride or 2-Chloro-1-methylpyridinium Iodide in the Presence of Amines: A Correction

Article abstract of DOI:10.1055/s-1989-27154

Hydroxamic acids reacted with amines in the presence of either p-toluenesulfonyl chloride or 2-chloro-1-methylpyridinium iodide to produce compounds whose structures are different from those which had been reported.These reactive halides converted hydroxamic acids first to Lossen-type of intermediates, which rearranged spontaneously in basic media to isocyanates which reacted further.In the absence of primary or secondary amines in the medium, the intermediate isocyanates acylated the starting hydroxamic acids to form O-carbamyl hydroxamic acids.However, when the reaction mixtures contained either primary or secondary amines, addition to the intermediate isocyanates provided ureas.Furthermore, it was found that amines caused the O-carbamyl hydroxamic acids to undergo facile Lossen degradations to furnish ureas.