title: Transmetallation versus β-hydride elimination: the role of 1,4-benzoquinone in chelation-controlled arylation reactions with arylboronic acids.
abstract: The formation of an atypical, saturated, diarylated, Heck/Suzuki, domino product produced under oxidative Heck reaction conditions, employing arylboronic acids and a chelating vinyl ether, has been investigated by DFT calculations. The calculations highlight the crucial role of 1,4-benzoquinone (BQ) in the reaction. In addition to its role as an oxidant of palladium, which is necessary to complete the catalytic cycle, this electron-deficient alkene opens up a low-energy reaction pathway from the post-insertion σ-alkyl complex. The association of BQ lowers the free-energy barrier for transmetallation of the σ-alkyl complex to create a pathway that is energetically lower than the oxidative Heck reaction pathway. Furthermore, the calculations showed that the reaction is made viable by BQ-mediated reductive elimination and leads to the saturated diarylated product.
authors.affiliation: Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, BMC, P.O. Box 574, SE-751 23 Uppsala, Sweden. christian.skold@orgfarm.uu.se
authors.forename: Christian
authors.initials: C
authors.lastname: Sköld
authors.forename: Jonatan
authors.initials: J
authors.lastname: Kleimark
authors.forename: Alejandro
authors.initials: A
authors.lastname: Trejos
authors.forename: Luke R
authors.initials: LR
authors.lastname: Odell
authors.forename: Sten O
authors.initials: SO
authors.lastname: Nilsson Lill
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Norrby
authors.forename: Mats
authors.initials: M
authors.lastname: Larhed
mesh_terms: D000475:Alkenes / Q000737:chemistry; D016227:Benzoquinones / Q000737:chemistry*; D001897:Boronic Acids / Q000737:chemistry*; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D000475:Alkenes; D016227:Benzoquinones; D001897:Boronic Acids; D002614:Chelating Agents; D028561:Transition Elements; D010165:Palladium