Computational Studies on the BF₃-Catalyzed Cycloaddition of Furan with Methyl Vinyl Ketone:  A New Look at Lewis Acid Catalysis

Abstract

Transition structures for both uncatalyzed and BF3-catalyzed Diels-Alder reactions involving furan and methyl vinyl ketone have been determined at the hybrid DFT (B3LYP/6-31G*) level of theory. The transition structures are predicted to be relatively concerted and highly asynchronous in all cases. A subsequent bond-order analysis has been carried out at the MP2/6-31G*//B3LYP/6-31G*. The role of the Lewis acid and the origin of the endo selectivity have been discussed in terms of the nature and number of interactions present in the four possible transition structures. The partition of the potential energy barrier has also been used to estimate the contributions of the pure deformation energy and the differential interaction between the reaction partners on passing from the ground state to the saddle point. This analysis reveals that the major influence arises from the heterodiene-dienophile interaction instead of that corresponding to a BF3-dienophile interaction.

Kinetics Study and Theoretical Modeling of the Diels−Alder Reactions of Cyclopentadiene and Cyclohexadiene with Methyl Vinyl Ketone. The Effects of a Novel Organotungsten Catalyst

“…We did not find any low-lying [2 + 4] hetero-DA transition states that are sometimes artifacts of low-level Hartree-Fock calculation. 28,29,31,32 Recent studies by Silva et al, 33 Tanaka and Kanemasa, 34 and Roberson et al 35 also suggested that Lewis acid catalyzed cycloaddition reactions might occur through a stepwise mechanism. However, their semiempirical and Hartree-Fock calculation very likely overestimated the energy barriers of the second TS due to the implicit treatment or omission of the electron correlation energies.…”

“…This is consistent with several earlier studies. [25][26][27][28][29] The MP2/6-31+G* method predicted bond lengths of 2.149 and 2.522 Å for the forming C-C bonds in the endo-cis TS of the CP/MVK system and 2.152 and 2.596 Å for the CH/MVK system. These values are compared to 2.279 Å for the parent DA reaction (1,3-butadiene + ethylene) calculated at the same level of theory.…”

“…[27][28][29][30] Structures. The calculated structures of the Cat-TS are depicted in Figures 5 and 6 and the calculated bond lengths of the two forming C-C bonds are shown in Table 13.…”

Theoretical Calculations of Metal‐Catalyzed Cycloaddition Reactions

“…The reaction of methyl vinyl ketone with furan catalyzed by BF 3 was studied by Babiano et al [22]. The transition states predicted were also relatively concerted and highly asynchronous for all the reaction paths studied.…”

Reactivity of Single‐Walled Carbon Nanotubes in the Diels–Alder Cycloaddition Reaction: Distortion–Interaction Analysis along the Reaction Pathway

“…[53] As shown in Figure 1( Colored pictures are shown in Supporting Information), distortion/interaction analysis( also knowna st he Activation Strain Model) [54] is ap owerful toolf or understanding reactivity in bimolecular reactions;i nt his model,t he activation energy (DE°)i sd ivided into ad istortion energy term (DE dist )a nd an interaction energy term (DE int ). [55][56][57][58][59][60][61][62][63][64][65][66] The distortion energy is the energy needed to distort reactants to the geometry they adopt in the transitions tate and the interaction energy is the energy change upon interaction of the two distorted fragments.T he distortion/interactiona nalysis is frequentlye mployed to explain the reactivity observed in 1,3dipolar cycloadditionsa nd other cycloaddition reactions. [67][68][69] The reactivities of these types of reactionsc orrelate wellw ith the distortion energies due to the small differences in the interaction energies.…”