Groebke-Blackburn-Bienaymé multicomponent reaction: emerging chemistry for drug discovery.

The Groebke-Blackburn-Bienaymé reaction (GBBR) is used for the one-pot synthesis of therapeutically relevant fused imidazoles bridgehead nitrogen heterocyclic compounds from readily available aldehyde, isocyanide and amidine building blocks. The reaction is driven by a wide range of catalysts and can be performed either under solvent or solvent-free conditions, or under microwave irradiation as heat source. The GBBR products can be used for the synthesis of a variety of more complex scaffolds via postmodification reactions. These include cyclization and nucleophilic substitution as well as further MCRs. The GBBR reaction has seen diverse applications in combinatorial and medicinal chemistry and its products are of great use in drug discovery. In this review, we summarize the efforts of the chemistry community in the progress and applications of GBBR since 1998. This review also includes some biological profiles and synthetic scopes of GBBR products. The component variations, postmodifications and secondary transformations will also be discussed throughout this review.