The First Stable Methyl-Substituted Disilene: Synthesis, Crystal Structure, and Regiospecific MeLi Addition

The reductive debromination of 3,3-dibromo-1,1,5,5-tetra-tert-butyl-2,4-bis(di-tert-butylmethylsilyl)-1,2,4,5-tetramethylpentasilane, [(tBu2MeSi)2MeSi]2SiBr2
(1), gave (E)-[(tBu2MeSi)2MeSi](tBu2MeSi)SiSiMe(SiMetBu2) (3), which is the first methyl-substituted
isolable disilene, and its structure was determined by
X-ray crystallography. The regioselective addition of a
methyl anion to the SiSi bond in 3 took place to give
the solvent-separated silyl anion species tetrakis(tetrahydrofuran)lithium(I) 1,1,5,5-tetra-tert-butyl-2,3-bis(di-tert-butylmethylsilyl)-1,2,4,4,5-pentamethylpentasilan-3-ide (4).