Tetrahydrofuran → (2S,4R)-1-(3-Benzothiazol-2-yl-5-chloro-2-oxo-2,3-dihydro-1H-indol-3-yl)-4-hydroxy-pyrrolidine-2-carboxylic acid dimethylamide

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Reaction Steps

(2S,4R)-4-hydroxy-pyrrolidine-2-carboxylic acid dimethylamide hydrochloride (0.78 g, 4.0 mmol) was added to a solution of the intermediate from step B in a mixture of dichloromethane (9 ml), THF (2 ml) and DIPEA (2 ml). The reaction mixture was stirred at room temperature for 48 h. After addition of water, the mixture was extracted four times with ethyl acetate. The combined organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure. The less polar diastereomer, as judged by thin-layer-chromatography using 5% MeOH in dichloromethane, precipitated on concentration and was filtered off. Purification by chromatography (silica gel, 5% MeOH in dichloromethane) resulted in 0.28 g of the less polar diastereomer. Purification by chromatography (silica gel, 5% MeOH in dichloromethane) of the mother liquor resulted in 0.36 g of the more polar diastereomer.

Provenance & Evidence