Solid-Phase Synthesis of Imidazo[1,2-a]-
pyridine-8-carboxamides

Significance

The polymer-bound 2-aminonicotinate 3, prepared from 4-hydroxyphenyl-sulfide resin 1 with protected 2-aminonicotinic acid 2 reacted with α-haloketones 4 (XCH₂COR¹) to give the resin-bound imidazo[1,2-a]pyridine-8-carboxlates 5. Halogenation of 5 with N-bromosuccin­amide or N-chlorosuccinamide took place selectively at the 3-position to give compound 6 or 7. The desired imidazo[1,2-a]pyridine-8-carbox­amides 9 were cleaved from the solid-supported compounds using an excess amount of primary or secondary amines 8. The simple and efficient one-step synthesis of triazolopyridines was described.