ZnII- and AuI-Catalyzed Regioselective Hydrative Oxidations of 3-En-1-ynes with Selectfluor: Realization of 1,4-Dioxo and 1,4-Oxohydroxy Functionalizations

Catalytic 1,4-dioxo functionalizations of 3-en-1-ynes to (Z)- and (E)-2-en-1,4-dicarbonyl compounds are described. This regioselective difunctionalization was achieved in one-pot operation through initial alkyne hydration followed by in situ Selectfluor oxidation. The presence of pyridine alters the reaction chemoselectivity to give 4-hydroxy-2-en-1-carbonyl products instead. A cooperative action of pyridine and Zn(II) assists the hydrolysis of key oxonium intermediate.