Enantioface differentiation by using soluble chiral polymers having 2,3-exo-bornanediol groups

Soluble linear polymers containing 2,3-exo-dihydroxy-3-endo-p-tolyl-3-bornyl groups prepared by reaction of lithiated linear polystyrenes with (-)-2-exo-hydroxy-3-bornanone, are treated with lithium aluminium hydride to form complexes which can be used as reducing reagents. The highest enantioselectivity compared with those cases using crosslinked polystyrene as carrier and chiral low molecular weight compounds is achieved by linear polystyrene having chiral groups. The advantages of soluble polymer-bound chiral reagents are discussed. The effect of alcohols, the reaction temperature, the sort of solvents, and the molar ratio of the reagent to ketone on the asymmetric reduction is also discussed.