Enediolates from carboxylic acids react readily with cyclic α-chloroketones to give the corresponding γ-chloro-β-alkoxycarboxylate intermediates depending on the ring size. Small ring ketones lead to γ-chloro-β-hydroxy acids in a highly stereoselective way, whereas medium ring ketones give a mixture of β,γ-epoxy acids and γ-lactones.
neighbouring-group effects - diastereoselectivity - carboxylic acids - carbanions - lactones
