ChemInform Abstract: Deprotonative Metalation of Functionalized Aromatics Using Mixed Lithium-Cadmium, Lithium-Indium, and Lithium-Zinc Species

Autor: Ghenia Bentabed-Ababsa, Masanobu Uchiyama, Aicha Derdour, Katia Snégaroff, Floris Chevallier, Florence Mongin, Tan Tai Nguyen, Jean‐Martial L'Helgoual'ch, Mitsuhiro Yonehara
Rok vydání: 2010
Předmět:
Zdroj: ChemInform. 41
ISSN: 1522-2667
0931-7597
DOI: 10.1002/chin.201006048
Popis: 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.
Databáze: OpenAIRE
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