Racemization mechanism of lithium tert ‐butylphenylphosphido‐borane: A kinetic insight
Résumé
The racemization mechanism of tert-butyl-
phenylphosphido-borane is investigated experimentally and
theoretically. Based on this converging approach, it is shown,
first, that several phosphido-borane molecular species
coexist at the time of the reaction and, second, that one
particular of both initially assumed reactive routes most
significantly contribute to the overall racemization process.
From our converging modelling and experimental
measurement, it comes out that the most probable species to
be here encountered is a phosphido-borane-Li(THF)2 neutral
solvate, which P-stereogenic center monomolecular
inversion through a Y-shaped transition structure (ΔrG°≠: 81
kJ.mol-1) brings the largest contribution to the racemization
process