Nef-isocyanide-Perkow access to novel pyrazolone derivations containing a cyclic ketene dithioacetal moiety

Pyrazolone compounds are privileged scaffolds in organic synthesis by virtue of their potential biological activities and wide-ranging utility as synthetic intermediates.1 Bioactive compounds bearing pyrazolone systems have attracted much interest in medicinal chemistry. Recently, the construction of structurally diverse pyrazolone derivatives has attracted the research interests of synthetic chemists. As part of our current studies on developments of new applications of pyrazolone derivatives in heterocyclic synthesis,2,3 we now report the formation of novel cyclic ketene dithioacetals containing a pyrazolone motif from the reaction between 2-pyrazolin-5-ones-CS2 adduct and phosphorylated hydroxyketenimines [generated in situ from Nef-isocyanide Perkow reaction], in the presence of Et3N as a base, at room temperature.4 The structures of the products were determined by their spectroscopic data and X-ray crystallography. Various features of these transformations will be presented and discussed.

Keywords:

Pyrazolone , Nef-isocyanide-Perkow reaction , Cyclic ketene dithioacetal , CS2 , Polarized double bond