CeCl<sub>3</sub>/<i>n</i>‐BuLi: Unraveling Imamoto's Organocerium Reagent
Tassilo Berger, Jakob Lebon, Cäcilia Maichle‐Mößmer, Reiner Anwander
Abstract
Abstract CeCl 3 (thf) reacts at low temperatures with MeLi, t‐BuLi, and n‐BuLi to isolable organocerium complexes. Solvent‐dependent extensive n‐BuLi dissociation is revealed by 7 Li NMR spectroscopy, suggesting “Ce( n‐ Bu) 3 (thf) x ” or solvent‐separated ion pairs like “[Li(thf) 4 ][Ce( n‐ Bu) 4 (thf) y ]” as the dominant species of the Imamoto reagent. The stability of complexes Li 3 Ln(n‐Bu) 6 (thf) 4 increases markedly with decreasing Ln III size. Closer inspection of the solution behavior of crystalline Li 3 Lu(n‐Bu) 6 (thf) 4 and mixtures of LuCl 3 (thf) 2 /n‐BuLi in THF indicates occurring n‐BuLi dissociation only at molar ratios of <1:3. n‐BuLi‐depleted complex LiLu(n‐Bu) 3 Cl(tmeda) 2 was obtained by treatment of Li 2 Lu(n‐Bu) 5 (tmeda) 2 with ClSiMe 3 , at the expense of LiCl incorporation. Imamoto's ketone/tertiary alcohol transformation was examined with 1,3‐diphenylpropan‐2‐one, affording 99 % of alcohol.