Nanocrystalline titanium(IV) oxide as an efficient heterogeneous catalyst for tandem michael and nucleophilic 1,2-addition to enones

Abstract

Nanocrystalline titanium(IV) oxide was found to be an efficient heterogeneous catalyst for the conjugate 1,4-addition of indoles with α,β-unsaturated ketones to afford β-indolyl ketones in excellent yields. The subsequent catalytic 1,2-addition of Me₃SiCN to carbonyl compounds can be performed in one pot with moderate to good yields. Low sensitivity towards traces of moisture and high tolerance of different functional groups make nanocrystalline titanium(IV) oxide suitable for carrying out multistep synthetic sequences.