Mechanistic aspects of the isomerization of Z-vinylic tellurides double bonds in the synthesis of potassium Z-vinyltrifluoroborate salts.
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.
Stefani
Hélio A
HA
Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil. hstefani@usp.br
Guadagnin
Rafael C
RC
Keppler
Artur F
AF
Botteselle
Giancarlo V
GV
Comasseto
João V
JV
Suganuma
Carlos A
CA