P. Andrews, Magdalini Koutsaplis, E. Robertson
Feb 27, 2009
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0
Influential Citations
14
Citations
Journal
Organometallics
Abstract
Metalation of the chiral amine (S)-N-α-(methylbenzyl)allylamine with nBuM (M = Li, Na) leads to the formation of complexes with three distinct isomeric anion forms: allylamide [(PhC(H)CH3NCH2CH═CH2)]−, 1-aza-allyl [(PhC(H)CH3NC(H)CHCH3)]−, and aza-enolate [(PhC(═CH2)N(CH2CH2CH3)]−. The anionic form is dependent on the metal, the Lewis donor, and the thermal history of the complex. From their use in asymmetric syntheses and a previously described hmpa (hexamethylphosphoramide) complex, the allylamide form predominates with Li at room temperature in the presence of monodentate donors. The use of the bidentate donor tmeda (N,N,N′,N′-tetramethylethylenediamine) results in the crystallization and characterization of the 1-aza-allylic complex (S)-{[(PhC(H)CH3NC(H)CHCH3)Li}2·tmeda]∞, in which the allylamide moiety has undergone a 1,3-sigmatropic rearrangement. In the crystal structure, the tmeda molecules bridge rather than chelate the Li cations. The tridentate donor pmdta (N,N,N′,N′,N′′-pentamethyldiethylenetr...