- Carbon-silicon and carbon-carbon bond formation by elimination reactions at metal N-heterocyclic carbene complexes
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Two functional groups can be delivered at once to organo-rare earth complexes, (L)MR2 and (L)2MR (M = Sc, Y; L = ({1-C(NDippCH2CH2N)}CH2CMe2O), Dipp = 2,6-iPr2-C6H3; R = CH 2SiMe3, CH2CMe3), via the addition of E-X across the metal-carbene bond to form a zwitterionic imidazolinium-metal complex, (LE)MR2X, where LE = {1-EC(NDippCH2CH2N)}CH2CMe2O, E is a p-block functional group such as SiR3, PR2, or SnR 3, and X is a halide. The "ate" complex (L Li)ScR3 is readily accessible and is best described as a Li carbene adduct, ({1-Li(THF)C(NDippCH2CH2N)}CH 2CMe2O)Sc(CH2SiMe3)3, since structural characterization shows the alkoxide ligand bridging the two metals and the carbene Li-bound with the shortest yet recorded Li-C bond distance. This can be converted via lithium halide-eliminating salt metathesis reactions to alkylated or silylated imidazolinium derivatives, (L E)ScR3 (E = SiMe3 or CPh3). All the E-functionalized imidazolinium complexes spontaneously eliminate functionalized hydrocarbyl compounds upon warming to room temperature or slightly above, forming new organic products ER, i.e., forming C-Si, C-P, and C-Sn bonds, and re-forming the inorganic metal carbene (L)MR(X) or (L)2MX complex, respectively. Warming the tris(alkyl) complexes (LE)MR3 forms organic products arising from C-C or C-Si bond formation, which appears to proceed via the same elimination route. Treatment of (L)2Sc(CH 2SiMe3) with iodopentafluorobenzene results in the "reverse sense" addition, which upon thermolysis forms the metal aryl complex (L)2Sc(C6F5) and releases the iodoalkane Me3SiCH2I, again facilitated by the reversible functionalization of the N-heterocyclic carbene group in these tethered systems.
- Arnold, Polly L.,Turner, Zoe R.,Bellabarba, Ronan,Tooze, Robert P.
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p. 11744 - 11756
(2011/09/14)
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- Lithium-tellurium exchange reaction. A convenient method for generation of heteroatom-substituted methyllithiums
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A variety of heteroatom-substituted methyllithiums (GCH2Li; G = MeOCH2CH2O-, PhCH2O-, Me2N-, Me3Si-, Me3Ge-, nBu3Sn-, nBuTe-) were generated by the lithium-tellurium exchange reaction of corresponding tellurides with butyllithium and were trapped with electrophiles. The potent utility of bis(butyltelluro)methane as a methylene dianion synthon was demonstrated, where both of the butyltelluro groups were displaced stepwise by different electrophiles with use of this metalation/trapping sequence repeated twice.
- Hiiro, Tomoki,Atarashi, Yasunori,Kambe, Nobuaki,Fujiwara, Shin-Ichi,Ogawa, Akiya,Ryu, Ilhyong,Sonoda, Noboru
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p. 1355 - 1357
(2008/10/08)
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- Preparation of vinylstannanes via the Peterson reaction
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The condensation of anions derived from (phenylthio)(tri-n-butylstannyl)(trimethylsilyl)methane (2a), tert-butyl (tri-n-butylstannyl)(trimethylsilyl)acetate (2b), and (tri-n-butylstannyl)(trimethylsilyl)methane (2c) with carbonyl compounds was used to com
- Ager, David J.,Cooke, Glen E.,East, Michael B.,Mole, Susan J.,Rampersaud, Ashraff,Webb, Victoria J.
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p. 1906 - 1908
(2008/10/08)
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