C–O Coupling of Hydrazones with Diacetyliminoxyl Radical Leading to Azo Oxime Ethers—Novel Antifungal Agents

Abstract

Selective oxidative C–O coupling of hydrazones with diacetyliminoxyl is demonstrated, in which diacetyliminoxyl plays a dual role. It is an oxidant (hydrogen atom acceptor) and an O-partner for the oxidative coupling. The reaction is completed within 15–30 min at room temperature, is compatible with a broad scope of hydrazones, provides high yields in most cases, and requires no additives, which makes it robust and practical. The proposed reaction leads to the novel structural family of azo compounds, azo oxime ethers, which were discovered to be highly potent fungicides against a broad spectrum of phytopathogenic fungi (Venturia inaequalis, Rhizoctonia solani, Fusarium oxysporum, Fusarium moniliforme, Bipolaris sorokiniana, Sclerotinia sclerotiorum).

A review on oxime functionality: an ordinary functional group with significant impacts in supramolecular chemistry

“…Budnikov et al synthesized a series of novel azo-oxime ethers by selective oxidative C–O coupling of hydrazones with diacetyliminoxyl, which were found to be highly effective fungicides against a wide range of phytopathogenic fungal species. 50 The oxime ester moiety plays a significant role in bioactive compounds. 49 Other oxime ester compounds like Matrine ( Oxm-32 ), Fraxinellone ( Oxm-33 ) and Osthole ( Oxm-34 ) are well known for their strong pesticidal properties.…”