Hydrochloric Acid → 1-(Pyridin-4-yl)piperidin-4-one

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Reaction Steps

A solution of 79.7 g of the ketal prepared in a) in 2 l tetrahydrofuran is admixed with 1 l 6 n hydrochloric acid and the reaction mixture is stirred for 2 h at room temperature. Subsequently the tetrahydrofuran is removed in a vacuum on a rotary evaporator, the hydrochloric acid is made alkaline with semi-concentrated ammonium hydroxide solution and extracted four times with 100 ml methylene chloride each time. After drying the combined organic extracts over sodium sulfate and removing the solvent, the residue is purified by means of column chromatography on silica gel. 64.2 g (100% yield) 2,3,5,6-tetrahydro-[1,4']bipyridinyl-4-one is obtained in this manner as a grey powder. m/e=176; f.p.=102° C.

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