[4+2] Annulation of 3-(2, 2-diethoxyethyl)-1, 3-dicarbonyl compounds with indoles catalyzed by Brønsted acid ionic liquid for the synthesis of carbazoles. Issue 48 (28th November 2018) - Du, Yuying
Graphical abstract: Highlights: Various carbazoles were synthesized via [4+2] annulation. 1, 3-Dicarbonyl compounds and indoles afforded excellent yields of carbazoles. A Brønsted acid ionic liquid was proven to be effective catalyst for this reaction. The ionic liquid catalyst can be recycled at least three times. Abstract: Various carbazoles were synthesized via [4+2] annulation of 3-(2, 2-diethoxyethyl)-1, 3-dicarbonyl compounds with indoles. A Brønsted acid ionic liquid, [BPy]HSO4, was proven to be effective catalyst for this reaction. The ionic liquid catalyst can be recycled three times without significant loss of its catalytic activity.