Tunable Cu(i)-catalyzed site-selective dehydrogenative amination of β,γ-unsaturated hydrazones for divergent synthesis of pyrazol-4-ones and 1,6-dihydropyradazines

Abstract

A new tunable Cu(I)-catalyzed site-selective dehydrogenative amination of β,γ-unsaturated hydrazones has been established using readily accessible dioxygen as a green oxidant. The presence of Cu₂O/O₂ regiospecifically accessed densely functionalized pyrazol-4-ones with one quaternary carbon-amino functionality, in which O₂ acted as both a reaction component and an oxidant, whereas the employment of CuI/O₂ as a catalytic oxidation system resulted in 1,6-dihydropyradazines with good yields.