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

Authors: LEMAN KARADENİZ, GAMZE KOZ, KADRİYE AYDIN, STEPHEN THOMAS ASTLEY

Abstract: Using asymmetric Cobalt(III) salen catalysts, the ring-opening of epichlorohydrin by 2,3-dihydroxybenzal- dehyde and 2,4- dihydroxybenzaldehyde was found to occur at the phenolic groups most distant from the aldehydic group. Switching catalysts afforded a reversal in enantioselectivity. For 2,3-dihydroxybenzaldehyde and salicylaldehyde, addition of AlCl_3 to the reaction mixture led to an increase in reaction rate without any decrease in product enantiopurity.

Keywords: Asymmetric catalysis; salicylaldehyde; Co(III) salen; aryloxy alcohols; epoxide ring-opening

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