Cascade-Reaction Leading to an Intramolecular [2 + 4] Cycloaddition of a Phenyl Group by a Reactive Ge═Si Double Bond.

The reaction of GeCl·dioxane with 2 equiv of the thiolate LiSHyp [Hyp = Si(SiMe)] yields the germanide (12-crown-4)Li[Ge(SHyp)] (). A small structural variation in the substituent leads to a completely different result because the reaction of GeCl·dioxane with 2 equiv of the thiolate KSHyp [Hyp = Si(SiMe)(SiPh)] in toluene yields the unexpected compound [PhSi][MeSi]Ge[{(CH)PhSi}{SiMe}SiS]Si[SSiMe] () in high yield. The reaction cascade to give includes several rearrangement reactions and an intramolecular [2 + 4] cycloaddition of a phenyl ring. The syntheses and molecular structures of both compounds are presented, together with quantum-chemical calculations and NMR measurements, to enlighten the reaction mechanism behind the formation of .