Mechanism of catalytic cycloboration of α-olefins with boron trichloride: the synthesis of hardly obtainable boriranes and the mechanistic DFT study of transmetalation of titanacyclopropane intermediates

Current Trends in the Synthesis of Practically Important Five-Membered Boracarbocycles by Transmetalation of Aluminacarbocycles with Boron Halides

“…The mechanism of Al−B exchange was studied, taking into account possible reaction routes by the quantum-chemical method PBE/3z (Priroda 6.0) [24][25][26]. It has been established that acyclic Al,B-adducts 14 and 15 (Scheme 7) are formed with equal probabilities at the first stage, because both reactions (1) and ( 2) are characterized by negative Gibbs energies (−9.0 kcal/mol) and similar energy barriers.…”

Mechanism of Cp2ZrCl2-Catalyzed Olefin Cycloalumination with AlEt3: Quantum Chemical Approach

“…Quite a number of studies are devoted to theoretical and experimental verification of the transmetalation mechanism as a key step of cross-coupling reactions (Stille, Suzuki, and Negishi reactions), which are widely used in synthetic practice . The ligand exchange reactions in acyclic organometallic compounds are known to involve the formation of bimetallic associates without preliminary dissociation of one of the ligands; however, the replacement of zirconium by aluminum in metallacarbocycles is a more complex multistep process even for three-membered rings …”

Boron-containing small rings: synthesis, properties, and application prospects

“…The obtained experimental results allowed the authors to suggest that the synthesis of 1-halo-2-substituted bori- The mechanism for cycloboration of α-olefi ns was proposed on the basis of the results of quantum chemical DFT calculations of the thermodynamic and activation parameters of the possible pathways for the reaction of propene with BCl 3 . 62 In addition to BCl 3 , aryl(alkyl)dichloroboranes RBCl 2 (R = Ar, Alk) were proposed as boron reagents for Cp 2 TiCl 2-catalyzed of α-olefi ns.…”

“…Probably, low reactivity of arylalkyldichloroboranes is due to an increase in the energy barrier for the intramolecular cyclization step in comparison with that calculated for BCl 3 . 62 The barrier (or the activation energy E a ) for cyclo boration at room temperature was calculated to be ~20 kcal mol -1 .…”