Chiral benzyllithium compounds

Taking an example of a sulfur-stabilized benzyllithium compound, Hoffmann and coworkers performed two reactions of the racemic a-thio carbanion with a racemic or a chiral aldehyde [Eq. (3)] [17-19], and found that both reactions afford an identical diastereomeric ratio of the product. From these results, they have concluded that the sulfur-stabilized benzyllithium compound epimerizes faster than it reacts with the aldehyde, i.e., it is configurationally labile in THF at -78°C. 

The chiral benzyllithium compound generated by the reaction of the enan-tioenriched stannyl precursor with s-BuLi-(-)-sparteine was reacted with cyclohexanone to give the product with good enantioselectivity. Interestingly, this reaction proceeds with inversion of the configuration of the stannylated carbon [Eq.(43)j. 

Chiral benzyllithium compounds (90), generated by stereospecific deprotonation of the corresponding carbamate (89) with j-BuLi(TMEDA), maintain configurative... 

Compounds of Group 1. - (6Li, 15N) and (6Li, 13C) couplings were observed for mixed complexes formed between LiCH2CN and chiral lithium amides (1H, 6Li, 13C, 15N data).1 7Li and 31P H) HMQC experiments were used to assign the structures of benzyllithium complexes of /V-methyl-/V-ben-zylphosphinamide, e.g. (I).2 111 and 13C NMR and 13C-111 correlation spectra were used to confirm the presence of a C-Si-Ni-Li 4-membered heterocycle in [benzylbis(dimethylamino)-methylsilyl-K2-C,7V](7V, N, N, N -tetramethylenedia-mine-K2-iV,/V)lithium(I).3... 

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