# Cascade Reactions of Indigo with an Allenylic Reactant

## TL;DR

This paper describes a new chemical reaction involving indigo and an allenylic compound to create novel structures, offering insights into indigo's reactivity.

## Contribution

The study introduces two new heterocyclic scaffolds formed through indigo's allenylic alkylation, expanding its chemical potential.

## Key findings

- A base-enabled reaction of buta-2,3-dien-1-yl methanesulfonate with indigo produces benzoindolonaphthyridinedione and benzoazepinopyridoindolediones.
- The reaction forms two novel heterocyclic scaffolds, benzoazepinopyridoindolediones.

## Abstract

The base-enabled reaction of buta-2,3-dien-1-yl methanesulfonate with the readily available and cheap dye indigo resulted in the convenient one-pot synthesis of benzoindolonaphthyridinedione and benzoazepinopyridoindolediones, with the latter representing two novel heterocyclic scaffolds. Despite the low yields, the allenylic alkylation of indigo significantly contributes to the new chemistry of this compound, providing new mechanistic insights and reactivity boundaries.