The review discusses recent advancements in understanding electrocyclic reactions, moving beyond the traditional Woodward-Hoffmann rules by integrating time-resolved experiments with nonadiabatic quantum molecular dynamics simulations. The authors focus on studies of 1,3-cyclohexadiene and its derivatives to explain the mechanisms of photochemical electrocyclic reactions. The paper highlights progress in ultrafast electron diffraction techniques and simulation methods that can map molecular dynamics on a femtosecond to picosecond timescale.