NMR determination of the absolute configuration of a macrophomate synthase inhibitor by using an axial chiral reagent.

Macrophomate synthase catalyzes an extraordinary four-step transformation from oxalacetate and 2-pyrone to macrophomic acid by an intermolecular Diels-Alder reaction. The absolute configuration of the most potent macrophomate synthase inhibitor; (-)-2-carboxylmethyl-1-methoxybicyclo[2.2.2]oct-5-ene-2-carboxylic acid, was determined to be (1S, 2R, 4R) by using an axial chiral reagent.