Author ORCID Identifier

Thomas Gilbert:

Document Type


Publication Title

ACS Omega


Systematic computational studies of pericyclic Diels–Alder reactions between (H3C)2C═C(CH3)2, 1, and all permutations of substituted cyclopentadienes c-C5R1R2R3R4R5aR5b (R = H, CH3, CF3, F) allowed isolation of substitutional effects on Gibbs free energy barrier heights and reaction Gibbs free energies. “Average Substitution Gibbs Free Energy Correction” ΔGASC#‡/ΔGASC# values for each substituent in each position appeared to be additive. Substituent effects on barriers showed interesting contrasts. Methyl substitution at positions 5a and 5b increased barriers significantly, while substitution at all other positions had essentially no impact. In contrast, fluoro substitution at positions 5a and 5b lowered barriers more than substitution at other positions. Trifluoromethyl substitution mixed these effects, in that substitution at positions 5a and 5b increased barriers, but substitution at other positions lowered them. Despite the variances, ΔGASC#‡/ΔGASC# values allowed reliable prediction of barriers and exergonicities for reactions between 1 and highly substituted cyclopentadienes, and between 1 and cyclopentadienes with random mixtures of CH3/CF3/F substituents. ΔGASC#‡/ΔGASC# values were correlated with steric considerations and quantum theory of atoms in molecules (QTAIM) calculations. Overall, the ASC values provide a resource for predicting which Diels–Alder reactions of this type should occur at rapid rates and/or give stable bicyclic products.

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Publication Date


Original Citation

Austin S. Flemming, Brendan C. Dutmer, and Thomas M. Gilbert ACS Omega 2023 8 (15), 14160-14170 DOI: 10.1021/acsomega.3c00831


Department of Chemistry and Biochemistry



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