Phosphine-mediated addition of 1,2-dicarbonyls to diazenes: an umpolung approach toward N-acyl hydrazone synthesis

Abstract

Using a Kukhtin–Ramirez-like condensation employing hexamethylphosphorous triamide, the addition of 1,2-dicarbonyls to diazenes affords direct access to N-acyl hydrazones in moderate to excellent yields. The strategic assembly of this ubiquitous functional group proceeds through an umpolung disconnect in which an in situ generated acyl anion equivalent reacts with an electrophilic azodicarboxylate to form a new C–N bond. The method presented herein complements traditional condensation approaches toward hydrazone synthesis to access important synthetic intermediates and potentially biologically relevant architectures.