Carbon−Carbon Bond Activation by Rhodium(I) in Solution. Comparison of sp2−sp3 vs sp3−sp3 C−C, C−H vs C−C, and Ar−CH3 vs Ar−CH2CH3 Activation
| Autor: | Michael Gozin, Shyh-Yeon Liou, Yehoshoa Ben-David, Milko E. van der Boom, David Milstein |
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| Rok vydání: | 1998 |
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| Zdroj: | Journal of the American Chemical Society. 120:13415-13421 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | Reaction of [RhClL2]2 (L = cyclooctene or ethylene) with 2 equiv of the phosphine {1-Et-2,6-(CH2PtBu2)2C6H3} (1) in toluene results in a selective metal insertion into the strong Ar−Et bond. This reaction proceeds with no intermediacy of activation of the weaker sp3−sp3 ArCH2−CH3 bond. The identity of complex Rh(Et){2,6-(CH2PtBu2)2C6H3}Cl (3) was confirmed by preparation of the iodide analogue 6 by reaction of the new Rh(η1-N2){2,6-(CH2PtBu2)2C6H3} (7) with EtI. It is possible to direct the bond activation process toward the benzylic C−H bonds of the aryl−alkyl group by choice of the Rh(I) precursor, of the substituents on the phosphorus atoms (tBu vs Ph), and of the alkyl moiety (Me vs Et). A Rh(III) complex which is analogous to the product of insertion into the ArCH2−CH3 bond (had it taken place) was prepared and shown not to be an intermediate in the Ar−CH2CH3 bond activation process. Thus, aryl−C activation by Rh(I) is kinetically preferred over activation of the alkyl−C bond in this system. Moreover... |
| Databáze: | OpenAIRE |
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