Ranking of Organolithium Stability
The tin-lithium exchange reaction is an equilibrium process, where the most
stable organolithium is formed.  The ability or inability to transmetalate
various stannanes with BuLi allows us to rank the stability of
the anions, as shown below. Note that for the compounds that do not transmetalate,
it is important to show that the BuLi is attacking the tin. We
showed that this was the case. Click
here to review that experiment.
1. Sawyer, J. S.; Kucerovy, A.; Macdonald, T. L.; McGarvey, G. J. J.
Am. Chem. Soc., 1988, 110, 842.
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1. Transmetalation of acyclic aminostannanes:
Primary organolithiums can be formed, but secondary organolithiums cannot
2. Transmetalation of cyclic aminostannanes:
Secondary organolithiums are formed
3. Hypotheses: Conformational effects (i.e.,
a kinetic problem) or thermodynamics may be responsible
4. These studies allow a ranking of the relative stabilities of organolithiums.
5. How the aminostannanes were made