On the Solution Behaviour of Benzyllithium⋅(−)‐Sparteine Adducts and Related Lithium Organyls – A Case Study on Applying 7 Li, 15 N{ 1 H} HMQC and Further NMR Methods, Including Some Investigation into Asymmetric Synthesis

2D 7 Li, 15 N heteronuclear shift correlation through scalar coupling has successfully been applied to several lithium organyls consisting of polydentate N ligands such as N,N,N′,N′ ‐tetramethylethylenediamine (tmeda), N,N,N′,N′,N′′ ‐pentamethyldiethylentriamine (pmdta) and (−)‐sparteine. Structural insights on the conformation of benzyllithium ⋅ pmdta ( 5 ) in a toluene solution and the strength of ion pairing in combination with PGSE NMR measurements, 1 H, 1 H‐NOESY and 1 H, 7 Li‐HOESY experiments are presented. By studying in detail the formation of 5 in solution, a transient species has been observed for the first time and assigned to a pre‐complex of n BuLi and pmdta. In addition, the solution behaviour of the complex formed between benzyllithium and (−)‐sparteine ( 8 ) has been studied by PGSE and multinuclear NMR spectroscopy. The straightforward synthesis and first applications in asymmetric lithiations are also reported, which show that the new system benzyllithium ⋅ (−)‐sparteine ( 8 ) provide poorer enantioselective induction than the classical n BuLi ⋅ (−)‐sparteine ( 6 ). The results were supported by deprotonation experiments confirming that the formation of 8 relies on two relevant factors, namely temperature and lithiating reagent. The existence of 8 may thus interfere with the asymmetric induction when the system n BuLi ⋅ (−)‐sparteine is used in the enantioselective deprotonations of N ‐Boc‐ N ‐( p ‐methoxyphenyl)‐benzylamine conducted in toluene.