3-Indolylzinc halides

Indoles with carbocyclic halogen or triflate substituents are potential starting materials for vinylation, arylation and acylation via palladium-catalysed pro-cesses[l]. Indolylstannanes. indolylzinc halides and indolylboronic acids are also potential reactants. The principal type of substitution which is excluded from such coupling reactions is alkylation, since saturated alkyl groups tend to give elimination products in Pd-catalysed processes. 

The coupling of arylzinc halides with alkyl (E)-2,3-dibromoalkenoates occurs at C-3. 3-Arylindoles are obtained from 3-indolylzinc halides with haloarenes." A synthesis of 1,4-disubstituted butadienes starts from the hydrozirconation of ethynyl phenyl selenide. After Pd(0)-catalyzed coupling with alkenyl bromides, the seleno group is replaced via Grignard reaction in the presence of (Ph3P)2NiCl2. 

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