One set of peaks at 160-172 Hz corresponds to 1 JCH ~167 Hz, the one-bond coupling of a parahydrogen-derived proton to the 13 C nucleus (at 2.2% natural abundance due to the molecular symmetry) in dimethyl maleate, split by coupling to the proton of its second methine ( 12 CH) group. A second set of peaks at 185-205 Hz corresponds to 3 2 ⁄ ×133 Hz one-bond 1 H- 13 C coupling in dimethyl succinate, split by coupling to the protons in the other methylene ( 12 CH2) group. A simulated spectrum is shown beneath, and details of the simulations can be found in the Supporting Information. There is an additional peak in the succinate spectrum at 195 Hz that is not accounted for in the simulation. This peak grows and shrinks at the same rate as the other succinate peaks over the course of the reaction, and is possibly a side product such as monomethyl succinate or succinic anhydride; this is subject to further investigation. The J-couplings in the two product molecules are shown in Fig. . Some J-coupling values were taken from the literature as a starting point, and then the couplings were adjusted until the simulated spectra fit the data. We are able to extract not only the magnitude of the J-couplings, but also the relative signs. In addition, the zero-field spectra reveal details about the stereochemistry of the catalytic products. It has been reported in the literature that JH1H4 is larger than JH1H2 , and from this we were able to determine that the second p-H2 proton pair occupies positions H1+H4 (or equivalently H2+H3) on the final product. This is in agreement with the results reported in Ref. in which a fumaric acid-d2 precursor was used, and did not require partial isotopic labelling with deuterium. Details on how the simulations were performed are given in the Supporting Information.