Hydrochloric Acid → Ethyl 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine-6-carboxylate hydrochloride

Add 5 N hydrochloric acid (100 mL; 500.00 mmoles) and ethanol (200 mL) to a flask containing methyl imidazo[1,2-a]pyridine-6-carboxylate (4.98 g; 1.0 equiv; 28.27 mmoles) and 10% palladium on carbon (3.01 g; 0.1 equiv; 2.83 mmoles). Evacuate and backfill the reaction vessel with nitrogen (3×), then re-evacuate and backfill the reaction with hydrogen (3×). Heat the reaction mixture to 60° C. and vigorously stir under a hydrogen atmosphere for 24 hours, then evacuate and backfill the reaction vessel with nitrogen (3×) and filter the reaction mixture through Celite™, rinsing the filter cake with ethanol (100 mL). Concentrate the filtrate, add toluene (200 mL), and concentrate to dryness (repeat 2 times) to afford ethyl 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine-6-carboxylate hydrochloride (5.74 g; 88%) as a white solid. MS (m/z): 195(M+1).