STRUCTURAL NMR INVESTIGATIONS ON ALLYLLITHIUM COMPOUNDS

Four differently substituted phenylallyllithium compounds Li.2 have been investigated by dynamic H-1- and C-13-NMR, NOESY and HOESY spectroscopy. It is shown that a considerable barrier of rotation (ca. 40 kJ/mol) between the phenyl and the allyl moiety exists which is only slightly affected by the addition of TMEDA. The lithium atom prefers a bridged position with respect to the allylic part in solution and has HOESY contacts to the ortho hydrogen atoms of the aromatic ring.