Identification of the Aerobic Cp*Ge+ Decomposition Product Leads to Organic Deoxygenation Catalysts

The use of pyrylium and related catalysts for sp3 C–O bond reduction is reported. Studies on a cationic, divalent Ge complex ([Cp*Ge+][B(C6F5)4–]) used for deoxygenation reactions reveal that O2 is required for the oxidation of the complex into an active pyrylium catalyst. Reactivity screens show pyrylium, flavylium, and xanthylium catalysts are active, leading to a diverse, bench-stable, and highly tunable catalyst library.