The Reaction of Substituted Vinylsilanes with Lithium Metal

Non-Deprotonating Methodologies for Organolithium Reagents Starting from Non-Halogenated Materials. Part 2: Transmetallation and Addition to Multiple Bonds

“…Under some reaction conditions, the intermediate 240 rearranged to the conjugated dianion 241 (Scheme 63) [150]. Different vinylsilanes [151] and the tetrakis(trimethylsilyl)butatriene [152] were also reacted with lithium producing the corresponding dianions. The reduction product of 1,2-bis(silylethynyl)benzenes 242 and 243 with lithium naphthalenide underwent cyclisation forming the corresponding dianion 244 and 245, respectively [153].…”

Recent developments in homobimetallic reagents and catalysts for organic synthesis

“…It has been found that trimethylsilyl substituted styrenes can also be reduced by metallic lithium to form the corresponding 1,2-dilithio intermediate 8 (Scheme 4) [12]. Yus et al [13] successfully reduced methyl-substituted styrene with metallic lithium in the presence of a catalytic amount of 4,4′-ditert-bytylbiphenyl (DTBB).…”

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

“…Thus, the reaction of α-trimethylsilylstyrene (236) with lithium metal in ether at room temperature afforded exclusively the stable product of reductive dimerization 240, which was characterized by derivatization with dimethyl sulfate to give compound 244 (Scheme 54) [113]. Meanwhile, the lithiation under the same reaction conditions followed by reaction with dimethyl sulfate of the isomeric (Z)-β-trimethylsilylstyrene (237) and β,β-bis(trimethylsilyl) styrene (238) gave the corresponding compounds 245 and 246, respectively, 1,2-dilithioderivatives 241 and 242 being involved in these processes as reaction intermediates (Scheme 54) [113]. Finally, in the case of compound 239, lithiation at room temperature led first to the dilithium intermediate 243, which could not be characterized because it decomposed by carbon-carbon bond cleavage, leading to the organolithium species 247 and 248 (Scheme 54) [113].…”

“…Meanwhile, the lithiation under the same reaction conditions followed by reaction with dimethyl sulfate of the isomeric (Z)-β-trimethylsilylstyrene (237) and β,β-bis(trimethylsilyl) styrene (238) gave the corresponding compounds 245 and 246, respectively, 1,2-dilithioderivatives 241 and 242 being involved in these processes as reaction intermediates (Scheme 54) [113]. Finally, in the case of compound 239, lithiation at room temperature led first to the dilithium intermediate 243, which could not be characterized because it decomposed by carbon-carbon bond cleavage, leading to the organolithium species 247 and 248 (Scheme 54) [113]. Fürstner et al determined the structure of 1,2-dilithio-1,2-diphenyl-1,2-bis(trimethylsilyl)ethane, a compound similar to intermediates 241 and 242, by NMR spectroscopy and found that the phenyl groups had a high quinoid character and that the lithium cations were relatively mobile [114].…”