title: Thermodynamic control of 1,3-boratropic shifts of α- and γ-stannyl-substituted allylboranes: hyperconjugation outweighs steric effects.
abstract: (E)-δ-Stannyl homoallylic alcohols are prepared by an allene hydroboration-aldehyde allylboration sequence ( Chen , M. et al. J. Am. Chem. Soc. 2010 , 132, 7881 ). Key to this reaction sequence is that the kinetic allene hydroboration product, 2a, is less stable than and isomerizes to the more sterically congested α-stannylallylborane 3a (see abstract figure). An M06-2X density functional analysis shows that the C-Sn to boron σ-π hyperconjugation interaction is sufficiently stabilizing to override the steric congestion in 3a.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States.
authors.forename: Preston S
authors.initials: PS
authors.lastname: Stewart
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: William R
authors.initials: WR
authors.lastname: Roush
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Ess
mesh_terms: D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry*; D000466:Alkadienes / Q000737:chemistry*; D001880:Boranes / Q000737:chemistry*; D009947:Organotin Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000438:Alcohols; D000447:Aldehydes; D000466:Alkadienes; D001880:Boranes; D009947:Organotin Compounds; C025947:propadiene