Organolithium sparteine system

Remarkably, the closely related benzyllithium 304 is configurationally unstable even at -78 °C.138 Transmetallation of 303 (88% ee) at -78 °C gave an organolithium which reacted to give racemic product 305 in the presence or absence of TMEDA. Furthermore, the reaction of the 304-(-)-sparteine complex with each of racemic or enantiomerically pure 2 in a Hoffmann test gave the same 1 1.6 ratio of diastereoisomers. It is not yet clear whether this unexpected difference between 301 and 304 is due to an electronic difference between the naphthyl and phenyl systems, or whether it arises from the difference in steric hindrance, and therefore the dihedral angle between the ring and the amide, in the two compounds. 

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