CeCl3 /n-BuLi: Unraveling Imamoto's Organocerium Reagent.

CeCl3 (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 Li3 Ln(n-Bu)6 (thf)4 increases markedly with decreasing LnIII size. Closer inspection of the solution behavior of crystalline Li3 Lu(n-Bu)6 (thf)4 and mixtures of LuCl3 (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 Li2 Lu(n-Bu)5 (tmeda)2 with ClSiMe3 , at the expense of LiCl incorporation. Imamoto's ketone/tertiary alcohol transformation was examined with 1,3-diphenylpropan-2-one, affording 99 % of alcohol.