We explored the dynamics of the (4+2) mechanism through downhill molecular dynamics (MD) simulations using an MLP (Fig. Thiophene S,S-dioxides have rarely been exploited in synthetic contexts, but here are shown not only to offer efficient, stereoselective and general access to polycyclic indolines, but also to enable enantioselective syntheses of eight Strychnos alkaloids via the most concise routes reported to date.