α-Diazo-λ 3 -iodanes and α-diazo sulfonium salts: the umpolung of diazo compounds

Abstract

This article reviews the strategies available to achieve the umpolung of diazocompounds and the synthetic applications of such compounds. This minireview aims to cover the developments of the last few years in the design of reagents able to accomplish the umpolung of the azomethine carbon in diazo compounds namely, α-diazo-λ 3 -iodanes and α-diazo sulfonium salts. Specifically, the routes available for their preparation and a classification of their unique reactivity patterns (either acting as equivalents of carbene-radical or carbene-carbocation synthons) are discussed. We also present a detailed overview of the synthetic utility of such species and, when possible, a critical comparation their reactivity and properties.