Tetraamminecopper(II) Sulfate Monohydrate in Oxidative Azide-olefin Cyclo-addition and Three-component Click Reaction.

Abstract

An effective Cu-complex, [Cu(NH3)4SO4 • H2O] was prepared conveniently from the inexpensive and easily available starting reagents in a simple route. Excellent reactivity of the catalyst was observed towards two competent clickcycloadditions: (a) oxidative cycloaddition of azides with electron-poor olefins and (b) one-pot cycloaddition of alkynes with boronic acid and sodium azide under "click-appropriate" conditions. No external oxidant, short reaction time, high product yield, wide substrate scope, and aqueous solvent media make the azide-olefin cycloaddition approach a greener route in contrast to the reported methods. The newly developed mild, green, and rapid three-component strategy shows product diversity with superb yields at room temperature by reducing the synthetic process time and using only 1 mol % of the synthesized copper complex.