Water → Benzyl 4-(2-oxo-2,3-dihydro-imidazo[4,5-b]pyridin-1-yl)-piperidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

1108 g (2.85 mol) of benzyl 4-[1-(2-chloro-pyridin-3-yl)-ureido]-piperidine-1-carboxylate were refluxed with 720 g (8.57 mol) sodium hydrogen carbonate in 14.5 L of tert-amyl alcohol. 3 L of solvent were distilled off. The reaction mixture was cooled to 35° C. and mixed with 11 mL water. Then 13 g (0.058 mol) palladium acetate and 49 g (0.115 mol) 1,4-bis-(diphenylphosphino)-butane (DPPB) were added and the mixture was heated to reflux temperature. It was stirred at 100° C. until the reaction was complete, then cooled to RT and 7.5 L of water were added. The organic phase was separated off, washed with 5 L water and then evaporated down. Two lots of 3 L of isopropyl acetate were added to the oily residue and it was distilled off. Then the residue was dissolved hot in 7 L of isopropyl acetate and the mixture was slowly cooled to ambient temperature. The solid that crystallised out was suction filtered, washed with 2 L isopropyl acetate and tert.-butyl-methylether and dried at 50° C.

Provenance & Evidence