title: Mechanistic aspects of the isomerization of Z-vinylic tellurides double bonds in the synthesis of potassium Z-vinyltrifluoroborate salts.
abstract: Through direct transmetalation reaction of Z-vinylic tellurides with nBuLi was observed the unexpected isomerization of double bonds leading to potassium E-vinyltrifluoroborates salts in low to moderate yields. Using EPR spin trapping experiments the radical species that promoted the stereoinversion of Z-vinylic organometallic species during the preparation of potassium vinyltrifluoroborate salts was identified. The experiments support the proposed mechanism, which is based on the homolytic cleavage of the TenBu bond.
authors.affiliation: Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil. hstefani@usp.br
authors.forename: Hélio A
authors.initials: HA
authors.lastname: Stefani
authors.forename: Rafael C
authors.initials: RC
authors.lastname: Guadagnin
authors.forename: Artur F
authors.initials: AF
authors.lastname: Keppler
authors.forename: Giancarlo V
authors.initials: GV
authors.lastname: Botteselle
authors.forename: João V
authors.initials: JV
authors.lastname: Comasseto
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Suganuma