Necic acid synthons. Part 4. Regioselectivity in the reactions of chloro and lodo derivatives of selected 3-hydroxy-2-methylenealkanoate esters with ethyl 2-methyl-3-oxobutanoate

Abstract

Iodination of 3-hydroxy-2-methylenealkanoate esters with HI-H₃PO₄ proceeds with exclusive rearrangement, whereas in some cases, chlorination with hexachloroacetone–triphenylphosphine affords both normal and rearranged products. Substituent and solvent effects on the regioselectivity of nucleophilic displacement in these halogeno derivatives are discussed.