Organometallic reagents indole

There are a wide variety of methods for introduction of substituents at C3. Since this is the preferred site for electrophilic substitution, direct alkylation and acylation procedures are often effective. Even mild electrophiles such as alkenes with EW substituents can react at the 3-position of the indole ring. Techniques for preparation of 3-lithioindoles, usually by halogen-metal exchange, have been developed and this provides access not only to the lithium reagents but also to other organometallic reagents derived from them. The 3-position is also reactive toward electrophilic mercuration. 

Where a heterocyclic organometallic reagent is required, Grignard and zinc derivatives are often satisfactory complications sometimes attend the use of lithio derivatives. The use of boronic acids has become very popular on account of their clean reactions, general stability to air and water, and their compatibility with practically any functional group furan, thiophene, indole and pyridine boronic acids have all been used. " ... 

Other organometallic reagents such as Pt and Rh complexes are also found to be compatible catalysts in the AFC reactions. Song and co-workers reported the synthesis of the cationic pincer Pt" aqua complex 150 derived from a chiral bis(imidazolinyl)phenyl ligand. With 5 mol% of Pt complex 150 in toluene, the AFC alkylation of indoles with nitroalkenes proceeded to afford a variety of nitroalkylated indoles in good yields (up to 81%) with moderate to good enantioselectivity (up to 83% ee) (Scheme 6.68). 

A great deal of carbanirms, generated from C-H-active compounds, the Grignard reagents, the cyanide ion, all kinds of organometallic carbon-lithium derivatives, aromatic amines, phenols, pyrroles, indoles, thiophenes, furans, and other organic compounds with electron-rich carbon atoms have been involved in the Sn reactions as C-nucleoplules [1, 2, 10, 11, 114—117]. 

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