Some Aspects of the Chemistry of Nitro Compounds
Résumé
The present brief account relates our discovery of new reactions revolving around the chemistry of the NO2 group. It covers the condensation of MeNO2 with hindered ketones, and the synthesis of pyrroles, triazoles, and enamides. It also describes new transformations of allylic nitro compounds, such as their conversion to allylic sulfones and unsaturated lactones, their sigmatropic rearrangement into allylic nitrites and thence into allylic alcohols, as well as their use in a short synthesis of nitroestrone derivatives. This is followed by an unusual reduction method furnishing unsubstituted amines (RR'C?NH) under conditions where these hydrolytically labile species can be captured inter- or intramolecularly. Finally, a mechanistic study of a strange alkyne-forming reaction, first reported by Abidi and later shown by Corey and co-workers to proceed through allylic nitro intermediates, ultimately led to a practical and powerful synthesis of alkynes starting from beta-keto esters.