Alkylation of Indoles with α,β-Unsaturated Ketones using Alumina in Hexanes

Article abstract of DOI:10.1002/adsc.201901037

We evaluated the influence of solvent on the alumina-promoted C3-alkylation of indoles with α,β-unsaturated ketones. We found that lipophilic solvents were generally superior to hydrophilic ones with hexanes offering the 3-alkyl indole products in high yields. Thus, we demonstrate an inexpensive and procedurally simple new process that pairs acidic alumina with hexanes to achieve this important Michael alkylation. The substrate scope includes twenty-four examples with reaction yields ranging from 61 to 96%. (Figure presented.).