Product Class 14: Nitronic Acids and Their Derivatives

Abstract

Previously published information regarding this product class can be found in Houben-Weyl, Vol. E 14b, pp 780-960. In addition, three books [1][2][3] and five book chapters/reviews [4][5][6][7] covering the relevant topics have been published. Alkylideneazinic acid is the standard IUPAC nomenclature for this class of compounds. However, nitronates, aci-nitro compounds, nitronic acids, and nitronic esters are still used in this context because the IUPAC nomenclature is not as widely adopted as these common names. Where applicable, specific compounds are named using the aci-nitro prefix.Nitronates are not common because they are very labile, even at room temperature. They readily decompose when mixed with either acid or base. Thus, their applications have usually been limited to use as transient intermediates. Nevertheless, stable nitronic acids and silyl nitronates have been isolated and characterized, and their potential use in synthesis is attracting more and more attention from synthetic chemists.With regard to synthetic applications, nitronic acid is the intermediate in the Nef reaction, which is employed to convert nitroalkanes into carbonyl compounds. Nitronate salts, on the other hand, serve as nucleophiles in nitroaldol condensation reactions (e.g., the Henry reaction). More importantly for organic synthesis, nitronic esters and silyl nitronates are widely used in 1,3-dipolar cycloaddition reactions with dipolarophiles. These [3 + 2] cycloadducts provide a useful entry to heterocycles.