724425-50-7Relevant academic research and scientific papers
First-Row Transition Metal and Lithium Pyridine-ene-amide Complexes Exhibiting N- and C-Isomers and Ligand-Based Activation of Benzylic C-H Bonds
Lindley, Brian M.,Wolczanski, Peter T.,Cundari, Thomas R.,Lobkovsky, Emil B.
supporting information, p. 4656 - 4668 (2015/10/28)
Ene-amines Z-3-(2-pyridyl)-1-aza(2,6-iPr2-Ph)propene, (pynac)H, and 2-(2-pyridyl)-1-aza(2,6-R,R′-Ph)propene, (pyEA-ArRR′)H, were synthesized by condensation procedures; corresponding lithium or potassium ene-amides were prepared via standard deprotonation protocols. Addition of 2 equiv of (pynac)H to {(Me3Si)2N}2Fe(THF) or 2 Li(pynac) to FeBr2(THF)2 afforded (pynac)2Fe (1), while treatment of CrCl2(THF)2, MnCl2, FeBr2(THF)2, and CoCl2py4 with 2 equiv of (pyEA-AriPr2)K afforded pseudotetrahedral (pyEA-AriPr2)2M (2-M, M = Cr, Mn, Fe) and (pyEA-AriPr2)2Co-py (2-Co-py). Diamagnetic (κ-C,N-pyEA-AriPr2)3Co (3) was prepared in low yield (～7%) from CoCl2, and its Co-C(sp3) linkages are unusually low in field strength. Reactivity studies yielded little clean reactivity, but thermolysis of 2-Co-py afforded the bis-indolamide derivative {κ-N,N-N(C6H3(2-iPr)CMe2C(Me)(2-py)}2Co (5-Co), and related thermolyses of 2-M (M = Cr, Mn, Fe), conducted on NMR tube scales, generated related 5-M (M = Cr, Mn, Fe) at roughly the same rates. This observation prompted thermolyses of (pyEA-ArRR′)Li, which rearrange to their corresponding indolamides in >90% yields. Rate studies, accompanied by KIE and EIE observations, revealed that an initial hydrogen transfer is reversible and is likely to correspond to an anionic rearrangement, whereas C-C bond formation is rate-determining, as suggested by accompanying calculations. X-ray structure determinations of 1, 2-Fe, 2-Co-py, 3, and 5-Co were conducted.
