Computational studies of ene reactions between aminoborane (F₃C)₂BN(CH₃)₂and substituted propenes: additive effects on barriers and reaction energies

Abstract

Investigations of ene reactions between (F3C)2BNMe2 and substituted propenes reveal additive substitutional effects on barriers and reaction energies.

Additivity of Diene Substituent Gibbs Free Energy Contributions for Diels–Alder Reactions between (F3C)2B = NMe2and Substituted Cyclopentadienes

“…"Average Substitution Corrections" (denoted ΔG ASC# ‡ for electronic and Gibbs free energy barriers and ΔG ASC# for Gibbs free energy reaction energies, with # representing the position of interest) were determined as previously described. 4 Briefly, a substitution correction is the difference between an energy (barrier or overall reaction) determined for a Diels−Alder reaction for a cyclopentadiene with a particular substitution pattern and the energy determined for the reaction involving the cyclopentadiene with that pattern but lacking the substituent in the position of interest. The Average Substitution Correction is the average of all such substitution corrections for a particular substituent at a particular position.…”

“…We recently reported computational studies of pericyclic ene reactions between the dienophile (F 3 C) 2 B = NMe 2 , 1 , and all possible permutations of substituted propenes CR 1 R 2 CR 3 –CR 4 R 5 H (R = H, CH 3 , CF 3 , F) . Only one of these was predicted to be endothermic, and only a few combined small barriers with low exothermicities such that they might undergo retro-ene reactions.…”

“…We recently reported computational studies of pericyclic ene reactions between the dienophile (F 3 C) 2 B = NMe 2 , 1, and all possible permutations of substituted propenes CR 1 R 2 CR 3 − CR 4 R 5 H (R = H, CH 3 , CF 3 , F). 4 Only one of these was predicted to be endothermic, and only a few combined small barriers with low exothermicities such that they might undergo retro-ene reactions. We determined "Average Substitution Corrections" ΔE ASC# ‡ and ΔE ASC# as energetic positional energetic effects for each substituent, and discovered that barrier and product energetics for all permutations could be predicted accurately by summing ΔE ASC# ‡ and ΔE ASC# values.…”

Lewis Acidity of Carbon in Activated Carbonyl Group vs. B(C6F5)3 for Metal‐Free Catalysis of Hydrogenation of Carbonyl Compounds

“…[8][9][10] From a molecular perspective, the FLP-type heterolytic activation of the H 2 takes place throughout electrostatic and molecular orbital interactions between the H 2 , LA and LB molecules. [11][12][13][14][15][16][17][18] In FLP chemistry, it is important that the LA and LB molecules have enough noncovalent interactions to form an initial encounter complex. Calorimetric and kinetic studies have shown that entropic effects play an essential role in the formation of the encounter complex.…”

“…From a molecular perspective, the FLP‐type heterolytic activation of the H 2 takes place throughout electrostatic and molecular orbital interactions between the H 2 , LA and LB molecules [11‐18] . In FLP chemistry, it is important that the LA and LB molecules have enough noncovalent interactions to form an initial encounter complex.…”