Ethanol → ethyl (3RS,4RS)-2-[(1SR,2SR)-2-aminocyclohexyl]-3-(2,4-dichlorophenyl)-1-oxo-1,2,3,4-tetrahydroisoquinoline-4-carboxylate

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Reaction Steps

To 4.33 g of (3RS,4RS)-2-[(1SR,2SR)-2-aminocyclohexyl]-3-(2,4-dichlorophenyl)-1-oxo-1,2,3,4-tetrahydroisoquinoline-4-carboxylic acid were added 50 ml of ethanol and 2 ml of concentrated sulfuric acid, followed by heating under reflux overnight. Ethyl acetate and water were added thereto to carry out a liquid separation operation, and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution and a saturated aqueous sodium chloride solution. The organic layer was dried over anhydrous sodium sulfate and then evaporated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane-ethyl acetate) to obtain 2.3 g of ethyl (3RS,4RS)-2-[(1SR,2SR)-2-aminocyclohexyl]-3-(2,4-dichlorophenyl)-1-oxo-1,2,3,4-tetrahydroisoquinoline-4-carboxylate as a yellow foam.

Provenance & Evidence