Comparison of the NMR (methanol-d4) data for symphyocladin P (14) (Figures S42 and S43, Table 4, Table 5 and Table S13) with that for 10 revealed the key difference as replacement of the C-5 CO2Me moiety in 10 with a diastereotopic H2-4 olefinic methylene (δH 6.22/5.44). Comparison of the NMR (acetone-d6) data for symphyocladin Q (15) (Figures S44 and S45, Table 4, Table 5 and Table S14) with that for 14 revealed the key difference as an additional resonance, attributed to a C-6 CO2Me moiety (δH 3.71). Structure assignments for 14 and 15 were further supported by diagnostic 2D NMR correlations (Figure 4).