An Ir-catalyzed reductive formation of functionalized nitrones from N-hydroxyamides was reported. The reaction took place through two types of iridium-catalyzed reactions including dehydrosilylation and hydrosilylation. The method showed high chemoselectivity in the presence of sensitive functional groups, such as methyl esters, and was successfully applied to the synthesis of cyclic and macrocyclic nitrones, which are known to be challenging compounds to access by conventional methods. H-1 NMR studies strongly supported generation of an N-siloxyamide and an N,O-acetal as the actual intermediates.