Configurational Stability of [Di(amino)silyl]lithiums Having Cyclic Structures

Cyclic diamino-substituted silyllithiums, [(N,N ‘-diisopropyldiamino)silyl]lithiums, were prepared by the reaction of lithium with the corresponding chlorosilanes. The methyls in the isopropyl groups are diastereotopic and anisochronous at room temperature in THF and in diglyme. Variable-temperature NMR experiments revealed that the configuration at the lithium-bearing silicon atom is stable up to 333 K in THF and 388 K in diglyme.