SEARCH Articles Figures Tables 1.3- Dipolar cycloaddition reactions frontier molecular orbital theory 1.3- Dipolar cycloadditions frontier molecular orbital theory 1.3- dipolar cycloaddition reactions dominant frontier orbitals Frontier Frontier Orbital Interactions in the Transition States of One-Step 1,3-Dipolar Cycloadditions Sustmann Classification Frontier orbitals Orbital, frontier