Hydrochloric Acid → 1,2-Dihydro-3,5-dimethyl-5H-pyrido[1,2-a]-benzimidazolium perchlorate

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Reaction Steps

4-Ethoxycarbonyl-1,2-dihydro-3,5-dimethyl-5H-pyrido[1,2-a]benzimidazolium perchlorate (7.92g; 0.0213 mole) is boiled with stirring for 40 minutes in dimethylacetamide (50ml) containing concentrated HCl (3ml). During the reaction approximately half of the solution is allowed to boil away. The cooled reaction mixture is stirred overnight in a liter of ether. The ether is decanted and the residue is dissolved in hot water (300 ml) and filtered. Upon cooling to room temperature some gummy material separates on the walls of the flask. The clear solution is decanted, cooled with an ice bath, and treated with 30g of sodium perchlorate. The crude product which separates is filtered, washed with a little water then ether, and recrystallized from ethanol to give 3.28g (51.6%); m.p. 206°-210° d.

Provenance & Evidence