The regioselective alkylation of indoles with alcohols as alkylating reagents was developed by using Pd/C or RuCl2(PPh3)3/DPEphos {DPEphos = bis[(2‐diphenylphosphanyl)phenyl] ether}as catalysts. The reaction of indole with benzyl alcohol in the presence of Pd/C and K2CO3 at 80 °C for 24 h without any solvent under in air yielded 90 % of 3‐benzylindole. The corresponding 3‐benzylindole was obtained in 99 % yield when the reaction was catalyzed by RuCl2(PPh3)3/DPEphos in the presence of K3PO4 at 165 °C for 24 h under argon. Several types of alcohols were treated with indoles under these conditions to give the corresponding 3‐alkylated indoles in high yields (up to 99 %). This reaction may involve the catalyst‐mediated transformation of alcohols to aldehydes, nucleophilic addition of indole to the resulting aldehydes accompanied by dehydration, and then hydrogenation.

Transition-Metal-Catalyzed Regioselective Alkylation of Indoles with Alcohols. -Two sets of reaction conditions using Pd/C or RuCl2(PPh3)2/DPEphos as catalysts are developed for the C3-alkylation of indoles with a variety of alcohols. By using toluene as solvent bis(3-indolyl)arylmethane derivatives are obtained selectively. -(PUTRA, A. E.; TAKIGAWA, K.; TANAKA, H.; ITO, Y.; OE, Y.; OHTA*, T.; Eur. J. Org. Chem. 2013, 28, 6344-6354, http://dx.