Visible-Light-Driven Multicomponent Cyclization by Trapping a 1,3-Vinylimine Ion Intermediate: A Direct Approach to Pyrimido[1,2-b]indazole Derivatives

Here we develop a novel visible-light-driven three-component cyclization by trapping an 1,3-vinylimine ion-intermediate for the direct synthesis of pyrimido[1,2-b]indazole derivatives from bromodifluoroacetic acid derivatives, enaminones, and 3-aminoindazoles under mild conditions. Notably, the robust methodology provides a valuable opportunity for the introduction of aliphatic substituents and enables good compatibility of complex bioactive molecules. Furthermore, this is the first example of photoinduced multicomponent reaction by employing bromodifluoroacetic acid derivatives as a C1-synthon.

Automated summary

This study introduces a novel visible-light-driven three-component cyclization to synthesize pyrimido[1,2-b]indazole derivatives, allowing for the introduction of aliphatic substituents and good compatibility with complex bioactive molecules. It represents the first example of a photoinduced multicomponent reaction using bromodifluoroacetic acid derivatives as a C1-synthon.