Enantioselective addition of diethylzinc to aldehydes catalyzed by 3,3?-bis(2-oxazolyl)-1,1?-bi-2-naphthol (BINOL-Box) ligands derived from 1,1?-bi-2-naphthol

With 3,3′-bis(2-oxazolyl)-1,1′-bi-2-naphthols (BINOL-Box) synthesized from 1,1′-bi-2-naphthol (BINOL), the enantioselective addition of diethylzinc to aryl aldehydes proceeded smoothly to give secondary aryl alcohols in good yield with good enantioselectivity. Interestingly, the yields and enantioselectivities were affected by the mixing sequence of the reactants. Furthermore, the synthesis of both enantiomers of the addition products has been achieved using the same ligands by choosing achiral additives, Ti(O-iPr)4 and 4A molecular sieves.