The Synthesis of Transient Silenes using the Principle of the Peterson Reaction

Deprotonation of 1-hydroxyalkyltris(trimethylsilyl)silanes, (Me₃Si)₃Si-C(OH)R¹R² (1) with methyl lithium in ether at low temperature leads to transient silenes, (MeSi₂)₂Si=CR¹R² (2a: R¹ = R² = Me; 2b: R¹ = H, R² = tBu; 2c: R¹ = H; R² = Mes), which dimerize in absence of trapping agents to give 1-isopropenyl-2-isopropyl-1,1,2,2-tetrakis-(trimethylsilyl)disilane 3, (E)-3,4-di-/butyl-1,1,2,2-tetrakis(trimethylsilyl)-1,2-disilacyclo-butane 4 and (E)-1,2,3,8α-tetrahydro-l-mesityl-5,7,8α-trmiethyl-2,2,3,3-tetrakis(trimethyl-silyl)-2,3-disilanaphthalene 5, resp. Deprotonation of 1a-1c with excess organolithium reagents leads to trisilanes 6, the addition products of the nucleophilic organolithium compounds across the SiC bond of the intermediate silenes 2a-2c. Compounds 2b and 2c can also be trapped with 2,3-dimethyl-1,3-butadiene to give the silacyclohex-3-enes 9a and 9b. The interaction of 1a-1c with methyllithium or sodium hydride in THF causes a 1,3-Si-O trimethylsilyl migration resulting in formation of trimethylsiloxybis(trimethylsilyl)silyl-alkanes (Me₃Si)₂SiH-C(OSiMe₃)R¹R² 10a-10c. Deprotonation of 1c with methylmagnesium-bromide in THF gives (E)-2,4-dimesityl-1,1,3,3-tetrakis(trimethylsilyl)-1,3-disilacyclobutane 12