Isomeric esters of αβ-dihalogeno-β-formylacrylic acids

Abstract

Methyl esters derived from both the cyclic (hydroxy-lactone) and the open tautomeric structure of the respective acids have been prepared by esterification of αβ-dihalogeno-β-formylacrylic acids. The structure of the esters has been determined with the aid of u.v., i.r., and n.m.r. spectroscopy and by chemical methods. The normal esters are thermolabile and rearrange to the respective pseudo-esters. A mechanism for the rearrangement is suggested.