Abstract: The effects of alkoxy substitution on tetrahedral carbanions were studied by examining ligand selectivity in the tin-lithium exchange reaction in the corresponding stannanes. The thermodynamic stability of the derived organolithium species was studied by competitive exchange experiments and low-temperature NMR to reveal an order of decreasing stability as follows: R'OCH2Li> R10CH (R2) Li> MeLi> RLOCR2R3Li> n-BuLi ...