STRUCTURAL-PROPERTIES OF SOME C-2-SYMMETRICAL SCHIFF-BASES AND STEREOSELECTIVITY IN CYCLOPROPANATION OF STYRENE BY THEIR CU(I) COMPLEXES

C-2-symmetric Schiff bases derived from R-camphor and R-fenchone (1-6) were prepared, their configurational and conformational features dete rmined by 1D- and 2D-NMR spectra and supported by MM2 calculations. Th eir Cu(I) complexes prepared in situ were examined in cyclopropanation of styrene and low to medium e.e.'s (2-32%) were obtained. Correlatio n of the structure of E,E-1 and Z,Z-6 with enantioselectivity of their Cu(I) complexes revealed restricting steric requirements in the forme r, possessing gem dimethyl group in the proximity of the chiral centre , near to the coordination sphere of alkene and carbene, as the probab le origin of its higher enantioselectivity.