First example of FeCl3-catalyzed alkylation of indoles with pinenes

Indoles undergo smooth alkylation with α- and β-pinenes in the presence of 20 mol % of anhydrous FeCl3 under mild reaction conditions to produce a wide range of the corresponding 3-alkylated indoles in excellent yields with high trans-selectivity. This is the first example of alkylation of indoles with mono-terpenes.