1,4-Dioxane hydrochloride → (R)-2-(4-propyl-benzylcarbamoyl)-piperazine-1-carboxylic acid benzyl ester

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Reaction Steps

To the compound (2.64 g) obtained in Step 2 in 1,4-dioxane (13 ml) was added, with stirring at room temperature, 4N hydrogen chloride/1,4-dioxane (13 ml). After stirring at room temperature for 3 hr, the reaction mixture was concentrated under reduced pressure. Toluene was added to the residue, and the mixture was concentrated again under reduced pressure. The residue was partitioned by adding ethyl acetate and saturated aqueous sodium hydrogen carbonate solution. The organic layer was washed successively with water and saturated brine, dried over anhydrous magnesium sulfate, filtrated, and concentrated under reduced pressure. The residue was purified by column chromatography (5%-10% methanol/chloroform) to give the title compound (1.59 g).

Provenance & Evidence