Nitrosobenzenes as a stepping stone for the development of transition metal and metal-free organic transformations: a comprehensive review

Over the past few years, there has been exponential progress in the synthesis of value-added molecules utilizing nitroso compounds. The reactions of nitroso compounds with economically cheap reactive precursors have drawn much interest from organic chemists across the globe due to their high regioselectivities; enantioselectivities; and efficiencies for annulation, C–H activations, cycloaddition, Diels–Alder reaction, and notable metal-free reactions. In particular, the nitroso moiety has recently emerged as a powerful synthon and transformable directing group in direct C–H functionalization reactions. In this review, we have broadly discussed recent reports on the versatile applications of nitroso compounds as useful building blocks in the selective synthesis of a diverse range of molecules.