Carbon−Hydrogen Bond Activation of Aromatic Imines by (Cp*₂SmH)₂

Abstract

Treatment of (Cp* 2 SmH) 2 with 2-phenyl-1pyrroline forms product 1, via ortho-metalation. Complex 1 was characterized spectroscopically and by singlecrystal X-ray diffraction. The C-H bond activation reaction also occurs for acyclic aromatic ketimines and aldimines.

Organolanthanide-Catalyzed Imine Hydrogenation. Scope, Selectivity, Mechanistic Observations, and Unusual Byproducts

“…An ortho-metalated structure for 4a (for which there is considerable precedent , and an imine insertion related structure for 4b are proposed (Scheme 2) on the basis of the NMR data and D 2 O quenching/GC−MS analysis of the organic products 5a and 5b . Pressurizing the 4a / 4b reaction mixture ( 4a : 4b ≈ 1:3) to 20 psi of H 2 results in no change in the mixture composition after 22 h at room temperature.…”

“…We report here a catalytic, synthetic, and molecular structure study of organolanthanide-mediated imine hydrogenation, using well-defined precatalysts and focusing on scope, selectivity, mechanistic observations, and the informative nature of several unusual organolanthanide byproducts. Subsequent to our initial communication on this subject and while this paper was being completed, the stoichiometric, aryl C−H activating reaction of (Cp‘ 2 SmH) 2 (Cp‘ = η 5 -Me 5 C 5 ) with 2-phenyl-1-pyrroline and several acyclic benzylideneamines was communicated by Buchwald, Burns, et al …”

Co‐Condensation Reactions of Substituted Aromatic Compounds with Lithium Atoms at 77 K

“…Co-condensation of anisole with lithium atoms and THF at 77 K, led to the observed lithiated compound 2-methoxyphenyllithium, shown by NMR spectroscopy (as shown in Scheme 3). The ipso-carbon signal at δ ϭ 169.6 ppm and a singlet at δ ϭ 1.56 ppm in the 7 Li NMR spectrum, as well as the integration in the 1 H NMR spectrum clearly indicate a tetrameric structure in C 6 D 6 . [16] The yield of this reaction increased to 30% compared to 12% when toluene was used.…”

“…Another commonly used method is σ-bond metathesis using extremely electrophilic lanthanide centres as outlined below. [6] Figure 1. Selected examples of CϪH bond activation using metal complexes…”

Synthesis, Structure, and Reactions of Hydride, Borohydride, and Aluminohydride Compounds of the f-Elements

“…Treatment of [Cp* 2 SmH] 2 with 2-phenyl-1-pyrroline afforded the orthometalation product (eq 84); such C−H bond activation reactions were also observed with acyclic aromatic ketimines and aldimines …”