Solid-phase synthesis of thiazolo[4,5-b]pyridine derivatives using Friedländer reaction.

Traceless solid-phase synthesis of 2,5,6,7-tetrasubstituted thiazolo[4,5-b]pyridine derivatives is described. Thorpe-Ziegler type cyclization of solid supported cyanocarbonimidodithioate with alpha-halo ketones afforded thiazole resin, which were converted to the desired thiazolopyridine resin by the Friedländer protocol under microwave irradiation conditions. After oxidation of sulfides to sulfones, nucleophilic desulfonative substitution with amines gave the target thiazolo[4,5-b]pyridine derivatives in good overall yields.