Diels-Alder atom-economy framework: [4+2] cycloaddition conserves all atoms (atom economy = 1)

Diels-Alder [4+2] cycloaddition atom-economy analysis: the concerted 1,3-diene + dienophile → cyclohexene pericyclic reaction incorporates every atom of both reactants into the product, with zero by-product mass. Two new σ-bonds form…