Abstract
Advances in the last decade for the synthesis of the imidazo[1,2-a]pyridine scaffold from various substrates employing approaches such as multicomponent
reactions, tandem processes, rearrangement reactions, inter- and intramolecular oxidative/reductive
cyclizations, and transition-metal-catalyzed C–H activation are summarized in this
review. The mechanisms for the selected transformations are also discussed.
1 Introduction
2 From 2-Aminopyridines
2.1 Revisiting Traditional Cyclocondensation
2.1.1 Regioselectivity in Cyclocondensation
2.2 Reactions of Carbonyl Compounds
2.3 Reactions of α,β-Unsaturated Carbonyl Compounds
2.4 Reactions of Nitroolefins
2.5 Reactions of Alkynes
2.6 Multicomponent Reactions
2.6.1 Three-Component Reaction of Aldehyde, 2-Aminopyridine, and Isocyanide
2.6.2 Three-Component Reaction of 2-Aminopyridine, Aldehyde, and Alkyne
2.6.3 Other Multicomponent Procedures
2.7 Reactions of N-Substituted 2-Aminopyridines
2.8 Miscellaneous Reactions
3 From Pyridines
3.1 Multicomponent Reactions
4 From Pyridinium Salts
5 From Imidazoles
5.1 Reactions of Heterocyclic Ketene Aminals
6 Miscellaneous Methods
7 Conclusion
Key words
imidazo[1,2-
a]pyridine - 2-aminopyridine - tandem reaction - multicomponent reaction - C–H activation
