Rapid Access to Indoline Spiropyran Scaffolds by Domino‐Knoevenagel/oxa‐Diels‐Alder (DKODA) Reaction at Room Temperature

Abstract

A facile method has been developed for the synthesis of a novel indoline spiropyran derivatives via three‐component, catalyst‐free domino Knoevenagel/oxa‐Diels‐Alder (DKODA) reaction strategy at room temperature. The key step of the methodology is the in situ generation of oxa diene from Knoevenagel condensation of 4‐hydroxycoumarin 1 and aldehyde 2 undergoes oxa‐Diels‐Alder cyclization with dienophile 1,3,3‐trimethyl‐2‐methyleneindoline 3 to give the indoline spiropyran derivative 4.