Metal-Induced C-N Bond Cleavage in the Decomposition of Alkali (R,R)-Bis(α-methylbenzyl)amide Complexes

This study resulted in the isolation of new alkali metal complexes of (R,R)-bis(α-methylbenzyl)amine (B-α-mba) characterized by NMR spectroscopy and single-crystal X-ray diffraction where possible. The reaction outcome was found to be dependent on metal and Lewis donor choice to afford species [{PhCH(CH₃)}₂NLi·Dioxane]₂ 2, [{PhCH(CH₃)}₂NLi·HMPA]₂ 3, [{PhCH(CH₃)}₂NLi·TMEDA] 4, and [{PhCH(CH₃)}₂NNa·(THF)_k]_n 5 as simple amido species. Complex [{PhC(-CH₂)}{PhCH(CH₃)}NNa·TMEDA]_∞ 6 was isolated as a result of a β-hydride elimination. A complex mixture of species was isolated when B-α-mba was reacted with potassium in the presence of TMEDA and PMDETA to give species [{PhCH(CH₃)}₂NK·(TMEDA)_k]_n 7a, [{PhC(-CH₂)}{PhCH(CH₃)}NK·(TMEDA)_k]_n 7b, [{PhC(-CH₂)NH}K·(TMEDA)_k]_n 7c, [{PhCH(CH₃)}₂NK·(PMDETA)_k]_n 8a, [{PhC(-CH₂)}{PhCH(CH₃)}NK·(PMDETA)_k]_n 8b, and [{PhC(-CH₂)NH}K·(PMDETA)_k]_n 8c. In both cases, the decomposition to form the potassium enamide species 7c and 8c was the more favorable process. The decomposition reaction of B-α-mba with nBuNa in the presence of PMDETA to give the sodium enamide [PhC(-CH₂)N(H)Na·PMDETA] 1 was investigated with GC-MS studies revealing the byproduct of this decomposition as styrene.