N-Containing heterocyclic compounds are extremely important in the study of biological activity and for pharmaceutical utilization. Especially, imidazopyridines with both pyridine and imidazole moieties, which comprise a typical, privileged scaffold, exhibit gastroprotective properties and function as sedative, anxiolytic, and insomnia medicine. For this reason, the development of a synthetic method for imidazopyridine and its derivatives from easily accessible compounds is needed. So we developed a Cu-catalyzed, formal aza-[3 + 2] cycloaddition reaction with pyridine derivatives and α-diazo oxime ethers in trifluoroethanol to synthesize imidazopyridines with the release of molecular nitrogen and elimination of alcohol. This method enabled modular synthesis of a wide range of N-heterobicyclic compounds such as imidazopyridazines, imidazopyrimidines, and imidazopyrazines. This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2015H1C1A1035955).