Nonlinear relationship between the enantioselectivities for asymmetric reactions of monofunctional and bifunctional substrates. Synthesis of practically optically pure diols by the catalytic enantioselective diethylation of terephthalaldehyde

An equation is presented which shows a nonlinear relationship between the enantioselectivities for asymmetric reactions of bifunctional and monofunctional substrates; practically complete enantioselectivity (100% e.e.) was observed in the enantioselective diethylation of terephthalaldehyde with diethylzinc using N,N-di(n- butyl) norephedrine and (S)-diphenyl(1-methylpyrrolidin-2-yl) methanol as chiral catalysts.