Extended Data Fig. 6: Computed transition state (TS) energies for the pycnidione series (a) and the eupenifeldin series (b).

(a) The transition state (TS) energies to form experimental observed epolone B (2’) and pycnidione (1’). The competitive transition state pyc-TS2 for diastereoisomeric monoadduct 2’-a, and pyc-TS4,5,6 for bis-adducts 1’-a/b/c. The reaction barriers between the transition state pyc-TS1 and pyc-TS2 was 0.8 kcal· mol⁻¹, while the reaction barriers between the transition state pyc-TS3 and pyc-TS4 was 6.6 kcal· mol⁻¹; (b) The transition state eup-TS1 and eup-TS2 for monoadducts 2 (experimental product) and 2-a, and eup-TS3-TS6 for bis-adducts 1 (experimental product) and 1-a/b/c. The reaction barrier for the transition state eup-TS1 was 1.9 kcal· mol⁻¹ lower than eup-TS2, and the reaction barriers for the transition state eup-TS3 was 1.3 kcal· mol⁻¹ lower than eup-TS4. The energies shown in the figure are free energies, and were calculated using ωB97X-D/def2-QZVPP//ωB97X-D/def2-SVP.