HRESI(+)MS measurements suggested that 4 (C8H10O6, Δmmu +0.2) and 5 (C8H10O6, Δmmu +0.2) were isomeric dimethyl esters, and 6 (C9H12O6, Δmmu +0.1) was a trimethyl ester, of aconitic acid. Analysis of the NMR (methanol-d4) data for 4–6 (Figures S14–S19, Tables S3 and S4) confirmed these assignments, with E ∆3,4 configurations being inferred from diagnostic chemical shifts for H-4 and C-2 in aconitate D (4) (δH 6.91; δC 33.8), aconitate E (5) (δH 6.92; δC 33.9) and aconitate F (6) (δH 6.92; δC 33.8), and HMBC correlations permitting the assignment of the dimethyl ester regiochemistry across 4 and 5. For example, correlations from an OMe (δH 3.67) and H2-2 (δH 3.91) to C-1 (δC 172.5), and from an OMe (δH 3.80) and H2-2 to C-6 (δC 168.2), confirmed the presence of C-1 CO2Me and C-6 CO2Me moieties in 4, whereas correlations from an OMe (δH 3.67) and H2-2 (δH 3.91) to C-1 (δC 172.5), and from an OMe (δH 3.76) and H-4 (δH 6.92) to C-5 (δC 167.5), confirmed C-1 CO2Me and C-5 CO2Me moieties in 5 (Figure 2).