SEARCH Articles Figures Tables Concerted reactions orbital symmetry control Controlling symmetry Diels-Alder cycloaddition reaction orbital symmetry control Diels-Alder reaction symmetry control Symmetry control Symmetry controlled reactions Diels-Alder reaction Symmetry controlled reactions activation parameters Symmetry controlled reactions allowed Symmetry controlled reactions concerted v. stepwise Symmetry controlled reactions cycloaddition Symmetry controlled reactions electrocyclic Symmetry controlled reactions forbidden Symmetry controlled reactions secondary orbital interaction Symmetry controlled reactions sigmatropic rearrangements