Deprotonative Metalation of Functionalized Aromatics using Mixed Lithium-Cadmium, Lithium-Indium, and Lithium-Zinc Species - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Chemistry - A European Journal Année : 2009

Deprotonative Metalation of Functionalized Aromatics using Mixed Lithium-Cadmium, Lithium-Indium, and Lithium-Zinc Species

Résumé

In situ mixtures of CdCl(2)TMEDA (0.5 equiv; TMEDA = N,N,N',N'-tetramethylethylenediamine) or InCl(3) (0.33 equiv) with [Li(tmp)] (tmp = 2,2,6,6-tetramethylpiperidino; 1.5 or 1.3 equiv, respectively) were compared with the previously described mixture of ZnCl(2)TMEDA (0.5 equiv) and [Li(tmp)] (1.5 equiv) for their ability to deprotonate anisole, benzothiazole, and pyrimidine. [(tmp)(3)CdLi] proved to be the best base when used in tetrahydrofuran at room temperature, as demonstrated by subsequent trapping with iodine. The Cd-Li base then proved suitable for the metalation of a large range of aromatics including benzenes bearing reactive functional groups (CONEt(2), CO(2)Me, CN, COPh) or heavy halogens (Br, I), and heterocycles (from the furan, thiophene, pyrrole, oxazole, thiazole, pyridine, and diazine series). Five-membered heterocycles benefiting from doubly activated positions were similarly dideprotonated at room temperature. The aromatic lithium cadmates thus obtained were involved in palladium-catalyzed cross-coupling reactions or simply quenched with acid chlorides.

Domaines

Chimie organique
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Dates et versions

hal-00785064 , version 1 (05-02-2013)

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Katia Snégaroff, J.M. L'Helgoual'Ch, Ghenia Bentabed-Ababsa, Nguyen Tan Tai, Floris Chevallier, et al.. Deprotonative Metalation of Functionalized Aromatics using Mixed Lithium-Cadmium, Lithium-Indium, and Lithium-Zinc Species. Chemistry - A European Journal, 2009, 15 (39), pp.10280-10290. ⟨10.1002/chem.200901432⟩. ⟨hal-00785064⟩
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