title: Cations or Radicals? Inherent Reactivity of Biosynthetic Intermediates in the B-Ring Formation of Rotenoid Natural Products.
abstract: Compounds of the rotenoid class are naturally occurring in the Leguminosae and Nyctaginacae families. Rotenoids have found a myriad of uses, for example, in the agricultural industry as an insecticide and piscicide, and as an anticancer therapeutic. The scientific literature questions whether cyclization of the rotenoid B-ring occurs via a pathway containing either cationic or free-radical intermediates. In this work, both propositions are analyzed using DFT (B3LYP and M06-2X) and the G3 composite method in gas- and (implicit) solution-phase. The accuracy of these methods is compared to several experimental C-H bond dissociation energies (BDEs). We find that of the methods surveyed M06-2X provides the most accurate BDEs. Further, there is a clear thermodynamic preference for the free-radical pathway.
authors.affiliation: Department of Chemistry, Missouri State University , Springfield, Missouri 65897, United States.
authors.forename: Adam K
authors.initials: AK
authors.lastname: Kirkpatrick
authors.affiliation: Department of Chemistry, Missouri State University , Springfield, Missouri 65897, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Siebert
mesh_terms: D001688:Biological Products / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D012402:Rotenone / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001688:Biological Products; D002412:Cations; D005609:Free Radicals; D012402:Rotenone