| Abstract: | The investigation of the chemistry of indoles has been, and continues to be, one of the most active areas of heterocyclic chemistry.[1] In particular, β-indolylketones have received much attention as important building blocks for the synthesis of many natural products and other biologically active compounds.[2] In continuation of our work in the synthesis of indole derivates,[3] we describe the remarkable catalytic of PTSA as a cheaper catalyst in ultrasound-accelerated Michael reaction of indole with α, β-unsaturated ketones (2), which provide one of the most efficient routes to the synthesis of β-indolyketones. In all cases, the substitution on the indole nucleus occurred exclusively at the 3-position, and N-alkylation products have not been observed. In addition, the structure of 3a was further confirmed by single crystal X-ray crystallography. |
