81111-93-5Relevant articles and documents
General Method for the Preparation of Electron-Deficient Imidazo[1,2-a]pyridines and Related Heterocycles
McDonald, Ivar M.,Peese, Kevin M.
, p. 6002 - 6005 (2015)
A new annulation method for the preparation of the imidazo[1,2-a]pyridine ring system under mild conditions is presented. Treatment of a 2-aminopyridine with a dimethylketal tosylate in acetonitrile at elevated temperature (80-140°C) in the presence of catalytic Sc(OTf)3 provides the imidazo[1,2-a]pyridine product in good yield. The annulation method is broadly applicable to electron-poor 2-aminopyridines and displays a complementary profile to the classic preparation of the imidazo[1,2-a]pyridine ring system by reaction of a bromoketone with electron-rich and -neutral substrates. The scope of the process and mechanistic considerations are discussed.