Stereoselective adduct formation of α-acylcamphorato-copper(II) chelates with some chiral Lewis bases

Abstract

The formation constants of the mono-adducts of α-acylcamphorato-copper(II) chelates such as (+)-Cu(facam) 2, (−)-Cu(facam) 2, (+)-Cu(hfbc) 2 and (−)-Cu(hfbc) 2 with some chiral Lewis bases were determined spectrophotometrically in benzene. In order to compare the adduct formation constants obtained with the (+)- and (−)-forms, some pairs of chiral Lewis bases such as 1-amino-2-propanol [( R)(−), ( S)(+)], 1-(α-naphthyl)ethylamine [( R)(+), ( S)(−)], α-phenyl ethylamine [( R)(+), ( S)(−)] and also quinine and quinidine were examined as neutral ligands. Although not very pronounced, the effects of combinations obtained for (+)- or (−)-Cu(II) chelates and (+)- or (−)-ligands indicate that formation constants obtained by the formation of adducts with the ligands having different directions of the optical rotation seems to be superior to those with the same direction.