Substituent effects on the Diels-Alder reaction

Unsubstituted Case EWG-Aotivated Dienophiles Inverse Electron Demand 

HOMO-LUMO interactions are comparable II. Diene HOMO and dienophile LUMO interactions are dominant III. Diene LUMO and dienophile HOMO interactions are dominant 

Frontier orbital theory can also explain the regioselectivity observed when both the diene and alkene are unsymmetrically substituted.4 Generally, there is a preference 

361 (1975) I. Fleming, Frontier Orbitals and Organic Chemical Reactions, Wiley-Interscience, New York, 1976 O. Eisenstein, J. M. LeFour, N. T. Anh, and 

Concerted Cycloadditions, Unimolecular Rearrangements, and Thermal Eliminations 

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