Chiral tetranuclear and dinuclear copper(II) complexes for TEMPO-mediated aerobic oxidation of alcohols: are four metal centres better than two?

摘要: The one-pot reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde, (R)-2-aminoglycinol and Cu(OAc)2·2H2O in a 1 : 1 : 1 ratio the presence triethylamine led to isolation X-ray quality crystals chiral complex (R)-1 high yield. single crystal structure reveals tetranuclear copper(II) that contains {Cu4(μ-O)2(μ3-O)2N4O4} core. A using (1S,2R)-2-amino-1,2-diphenylethanol as precursor under same conditions generated (S,R)-2; its was determined by crystallography found contain {Cu2(μ-O)2N2O2} Both (S,R)-2 have been used for catalytic aerobic oxidation benzylic alcohols combination with TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) radical. selectively catalyses conversion various aromatic primary corresponding aldehydes yields (99%) TONs (770) air, while exhibits less promising performance conditions. role cluster structures controlling reactivity towards reactions is discussed.