Copper(I)/(tert-BuOOH)-induced activation of dioxygen for the ketonization of methylenic carbons

In acetonitrile/pyridine bis(bipyridine)copper(I) [CuI(bpy) 2 + ] activates HOOH and t-BuOOH for the selective ketonization of methylenic carbons. With 5 mM CuI(bpy) 2 + /100 mM HOOH(Bu) the conversion efficiencies [product per 2 HOOH(Bu)] for c-C6H12 are 31% (HOOH) and 59% (t-BuOOH, argon atmosphere), and for PhCH2CH3 are 24% (HOOH) and 64% (t-BuOOH, argon). With 5 mM CuI(bpy)2 and 10 mM t-BuOOH under argon the conversion efficiency for c-C6H12 is 10% and for PhCH2CH3 is 140%. However, in the presence of O2 (1 atm, 7 mM) the conversion efficiency for c-C6H12 increases to 67%, and for PhCH2CH3 to 440% [all PhC(O)Me (22 mM)], respectively. The latter result represents a CuI(bpy) 2 + / t-BuOOH-induced auto-oxygenation with at least 2.2 O2/catalyst turnovers. The first-formed intermediate is a one-to-one adduct [(bpy)2CuIOOBu-t + pyH+, 1], which reacts with (a) excess CuI(bpy) 2 + to give 2 (bpy) 2 + CuIIOH, (b) excess t-BuOOH to give O2 and t-BuOH, (c) excess c-C6H12 to give c-C6H11OH, (d) excess c-C6H12 and excess t-BuOOH to give c-C6H11OOBu-t, and (e) O2 to form an adduct, [(bpy)2CuIII(O2)(OOBu-t) + pyH+, 5], that reacts with (i) c-C6H12 to give c-C6H10(O) and c-C6H11OH and (ii) PhCH2CH3 to give PhC(O)CH3.