Discovery of Novel Imidazo[1,2-a]-involved N-Heterocyclic Drugs by Groebke-Blackburn-Bienayme Three-Component-Reaction

Katrin Groebke, Christopher Blackburn, and Hugues Bienayme have individually reported a three-component-reaction (3CR) among 2-aminopyridine, aldehyde, and isocyanide to afford imid- azo[1,2-a]pyridine in 1998. This multicomponent reaction was so-called as Groebke-Blackburn- Bienayme reaction (abbreviated as Groebke 3CR). The Groebke 3CR led to a convenient way for ac- cessing to a great abroad of imidazo[1,2-a]-contained N-heterocycles, which were believed to be anti- cancer, antibacterial, and antimalarial drugs or to be inhibitors for epoxide hydrolase, 5-lipoxygenase, and non-nucleoside reverse transcriptase, etc. The potent applications of the imidazo[1,2-a]-contained N-heterocycles triggered the research enthusiasm on the Groebke 3CR, including the expanding of the substrates, the changing of the substrates, and the exploring of the catalytic process. In particular, other substrates instead of 2-aminopyridine were employed in the Groebke 3CR, leading to the formation of different N-heterocycles for screening pharmacological activities. Taken collectively, more details of the Groebke 3CR should be revealed in the following re- searches in order to produce much more N-polyheterocyclic candidates for finding novel drugs.