Ethyl 4-oxoazepane-3-carboxylate--hydrogen chloride (1/1) → HCID 86754064, compound

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Reaction Steps

As in Example 2, 23.2 g of ethyl 4-oxo-azepan-3-carboxylate hydrochloride in 90 ml of ethanol were hydrogenated with a solution of 36.1 mg of the ruthenium catalyst in 10 ml of ethanol under 40 bar hydrogen pressure at 30° C. for 21 hours and at 50° C. for 3 hours. The residue, consisting of about 80% 3R,4R and 20% 3S,4R isomers, was triturated with tetrahydrofuran and ethanol at 50° C. for half an hour and at room temperature for 4 hours. The crystals were filtered off under suction, washed with a small amount of tetrahydrofuran/ethanol and dried to constant weight at 50° C./20 mbar, to yield 13.3 g of enantiomerically pure ethyl (3R,4R)-4-hydroxy-azepan-3-carboxylate hydrochloride in the form of white crystals.

Provenance & Evidence