Fig. 8: Summary of the experimental results and their computational rational based on FMO-analysis, activation barriers, mechanism (concerted vs. stepwise), and thermodynamics.
(A) Variation of the anthracene (exemplified for 1a and 1d) in presence of D leads to changes in the regioselectivity that are driven by kinetic parameters. (B) Based on the FMO analysis this regioselectivity is intrinsic to the anthracene (biggest orbital coefficients). On the contrary, changing the dieneophile from D to B this intrinsic and kinetic preference of the 1,4-product is overwritten by its unfavorable thermodynamics. The computational data was obtained at the B3LYP-D3/6-31 G** level of theory. Energies were calculated using the harmonic oscillator approach and include zero-point energy corrections (for further details see Supplementary Computational Studies). Color coding: yellow circles indication of biggest orbital coefficients for 9,10 addition, blue circles for 1,4 addition; blue numbers: ΔRG-values (driving forces), black numbers: ΔG≠ (activation barriers).
