| Hydroxamic acid and its derivatives are widely used in organic chemistry and pharmaceutical chemistry because of their special molecular structure and chemical properties.Here,a series of new reactions of hydroxamic acid and its derivatives have been developed,mainly including the following three aspects:(1)The synthsis of diphenylurea compounds via Ru-catalyzed Lossen rearrangement of hydroxyoxime derivatives.The diphenylurea compounds were synthesized in a one pot procedure via Ru-catalyzed Lossen rearrangement of hydroxyoxime derivatives.The proposed mechanism indicates that the isocyanate intermediates obtained from Lossen rearrangement is first hydrolyzed to form aniline,which is captured by another molecule of isocyanate to form the urea.(2)The cleavage of N-O/N-C bonds of hydroxamic acid derivatives under metal-free conditions.The breaking of N-O bond was achieved under the condition of DTBP,while the concurent breaking of both N-O and N-C bonds was achieved under the condition of TEMPO.We also found that the N-methoxy group is important for achieving cleavage of the N-C bond.(3)The synthesis of N-substituted formamdes under free metal conditions.The combined Lossen rearrangement and transamination reaction of hydroxamic acid was carried out under additive free conditions with formamide as the solvent and the formylation reagent,affording N-substituted formamdes in high yields. |
