Pirinccioglu, NecmettinRobinson, James J.Mahon, Mary F.Buchanan, J. GrantWilliams, Ian H.2024-04-242024-04-2420071477-05201477-0539https://doi.org/10.1039/b711538ehttps://hdl.handle.net/11468/16463Structural analysis of the bromo-beta-lactones obtained by addition of bromine to aqueous solutions of disodium 2,3-dimethylmaleate and 2,3-dimethylfumarate reveals stereochemistries opposite to those originally assigned in 1937: cis alkene yields erythro lactone, and trans alkene yields threo lactone. B3LYP/6-31+G(d) calculations using a PCM description of aqueous solvation confirm the validity of our proposed mechanism, in which the first-formed intermediate in each case is an a-lactone. The cyclic bromonium species is not an intermediate. An alternative pathway leading directly from cis alkene to cis lactone, via an unusual frontside displacement mechanism, is over 20 kJ mol(-1) higher in free energy. Hydrolysis of the bromo-beta-lactones yields bromohydrins whose stereochemistries as determined by X-ray crystallography indicate stereospecific formation by acyl-oxygen cleavage of the lactone ring, again contrary to the original view.eninfo:eu-repo/semantics/closedAccess[No Keyword]Experimental and computational evidence for ?-lactone intermediates in the addition of aqueous bromine to disodium dimethyl-maleate and -fumarateExperimental and computational evidence for ?-lactone intermediates in the addition of aqueous bromine to disodium dimethyl-maleate and -fumarateArticle52440014009WOS:0002512747000162-s2.0-367490447331804380610.1039/b711538eQ2Q1