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

Abstract

Alkyl (E)-2-(3-Alkyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)-5-(alkylamino)-1,3-dithiole-4-carboxylates have been obtained by condensation of 2-pyrazolin-5-ones with carbon disulfide followed by ring formation with phosphorylated hydroxyketenimines [generated in situ from Nef-isocyanide-Perkow reaction] in the presence of Et₃N. The structure of target compounds was confirmed by X-ray diffraction study. The good yields of the products, diastereoselectivity, and lack of activators or metal promoters are the main advantages of this method.

Graphical Abstract

Keywords:

• Pyrazolone
• Nef-isocyanide-Perkow reaction
• cyclic ketene dithioacetal
• carbon disulfide
• polarized double bond