Reagents indole

Electron-rich aromatic and heteroaromatic compounds are aminocyclopropylated by a cyclo-propaniminium ion which is generated from a cyclopropanone hemiaminal and titanium(IV) chloride or an acidic reagent. Indole, 1-methylpyrrole or phenol react in this way to give products 3, 4, and 5, respectively. Only C-alkylation at the phenol was observed when dimethylaminocyclopropanol and phenol were stirred in dichloromethane at 20 °C for 48 hours. This contrasts strongly with the alkylation of phenolate by a cyclopropaniminium ion leading to the 0-alkylated product. ... 

Although indoles are less reactive than pyrroles, they react with arenediazonium salts to give 3-(aryl-azo)indoles. The reaction with carbonyl compounds proceeds in an analogous way in the presence of acids. For this reason, indoles unsubstituted in the 3-position give a positive colour test with Ehrlich s reagent. Indole and acetaldehyde react via an azafulvenium salt to give 3-Vinylindole, which on further reaction with indole forms l,l-di(indol-3-yl)ethane ... 

Without additional reagents Indoles from arylazirines... 

As a direct route for the constructing carbon-carbon bonds, catalytic asymmetric Michael additions with various carbon-based nucleophiles including malonic esters, cyanide, electron-deficient nitrile derivatives, a-nitroesters, nitroalkanes, Horner-Wadsworth-Emmons reagent, indoles, and silyl enol ethers have attracted considerable attention. 

---