Reactivity of oximes for diverse methodologies and synthetic applications

Oximes are valuable synthetic building blocks with reactivity modes that enable their use in diverse methodologies, from cycloadditions to bioconjugation. Their reactivity towards photocatalysis and transition metals makes them ideal starting materials for N-containing heterocycles, amino alcohols and amines. Developments in oxime reactivity since 2016 have enabled transformations such as the addition of iminyl radicals to alkenes to generate functionalized imines, and [2 + 2]-cycloadditions to access azetidines. The unique properties imparted by the oxime N–O bond have also been used to integrate dynamic chemistries into materials. In this Review, we discuss the innovative use of this powerful functional group, with a focus on N–O bond fragmentation and cycloadditions, along with applications including dynamic materials, energetic materials and biocatalytic oxime reductions. We conclude by highlighting methodologies based on oxime starting materials, along with the challenges of using oximes for diverse applications, and offer insight into future directions in these areas. Oximes are valuable motifs with diverse reactivity. This Review outlines the breadth of oxime reactivity including N–O bond fragmentation through transition metal catalysis and photocatalysis, [2 + 2]-cycloaddition reactions, asymmetric reduction and applications in materials science. Developments in transition metal catalysis and photocatalysis highlight the use of oximes as powerful synthetic building blocks.