The Groebke-Blackburn-Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019-2023).

The Groebke-Blackburn-Bienaymé (GBB) three-component reaction, discovered in 1998, is a very efficient strategy to assemble imidazo[1,2- a ]-heterocycles starting from amidines, aldehydes and isocyanides. This review aims to exhaustively describe innovative aspects of this reaction achieved during the last five years, and classifies them into five categories: synthetic methods, building blocks, scaffolds, biological activities and physical properties.