COPPER(I)/(T-BUOOH)-INDUCED ACTIVATION OF DIOXYGEN FOR THE KETONIZATION OF METHYLENIC CARBONS

In acetonitrile/pyridine bis(bipyridine)copper(I) [Cu(I)(bpy)2+] activates HOOH and t-BuOOH for the selective ketonization of methylenic carbons. With 5 mM Cu(I)(bpy)2+/100 mM HOOH(Bu) the conversion efficiencies [product per 2HOOH(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 Cu(I)(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 Cu(I)(bpy)2+/t-BuOOH-induced autoxygenation with at least 2.2 O2/catalyst turnovers. In acetonitrile the bis(bipyridine)cobalt(II) [Co(II)(bpy)2(2+)] complex in combination with t-BuOOH also activates O2 for the ketonization of methylenic carbons but is about one-half as efficient as the Cu(I)(bpy)2+/t-BuOOH combination.