Continuous one-pot synthesis of new spiro-fused indoles from biobased building blocks using carbamoylation and imidation reactions under ultrasonic irradiation

Abstract

The application of a flow reactor under ultrasonic irradiation enabled the fast synthesis of new spiro-fused indoles in a one-pot methodology. The exploitation of the reactivity of biobased building blocks, including acrylic acids and formamides, was essential to achieve such highly functionalized molecular targets. A four-step process with a 2–3 min residence time, and no aqueous work-up, created spiro[indoline-succinimides], spiro[indole-pyrrolo-succinimides] and spiro[indole-pyrido-succinimides] with high overall yields.

Graphical Abstract