Visible-light-promoted N–H functionalization of O-substituted hydroxamic acid with diazo esters

Herein we report an N–H functionalization of O-substituted hydroxamic acid with diazo esters under blue LED irradiation conditions. The present transformations could be performed efficiently under mild conditions without use of catalyst, additive and N(2) atmosphere. Interestingly, when THF and 1,4-dioxane were employed as the reaction solvents, an active oxonium ylide involved three-component reaction and an N–H insertion of carbene species into hydroxamate occurred, respectively.