Jj. Robinson et al., Evidence for alpha-lactone intermediates in addition of aqueous bromine todisodium dimethyl-maleate and -fumarate, CHEM COMMUN, (5), 2001, pp. 485-486
Crystallographic analysis of the bromo-beta -lactones obtained by addition
of bromine to aqueous solutions of disodium 2,3-dimethylmaleate and 2,3-dim
ethylfumarate reveals stereochemistries opposite to those originally assign
ed and suggests that the first-formed intermediate in each case is an alpha
-lactone.