Co(III) catalysed asymmetric ring-opening of epichlorohydrin by salicylaldehyde derivatives: reversal of enantioselectivity and rate acceleration on addition of AlCl_3

摘要

Using asymmetric Cobalt(III) salen catalysts, thering-opening of epichlorohydrin by 2,3-dihydroxybenzal- dehyde and2,4- dihydroxybenzaldehyde was found to occur at the phenolic groupsmost distant from the aldehydic group. Switching catalysts afforded a reversal in enantioselectivity. For 2,3-dihydroxybenzaldehyde andsalicylaldehyde, addition of AlCl_3 to the reaction mixture led to anincrease in reaction rate without any decrease in productenantiopurity.