(S)-5-benzyloxymethyl-2,2-diphenylmorpholine-4-carboxylic acid tert-butyl ester → (R)-5-Formyl-2,2-diphenylmorpholine-4-carboxylic acid tert-butyl ester

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Reaction Steps

To 10% palladium on carbon (2.1 g) in ethanol (50 mL) add (S)-5-benzyloxymethyl-2,2-diphenylmorpholine-4-carboxylic acid tert-butyl ester (3.29 g, 7.16 mmol) in ethanol (75 mL) and stir under 1 atmosphere of hydrogen gas at room temperature for 4 hours. Filter and concentrate to give the desired compound as a white solid. Dissolve the solid in dimethylsulfoxide (20 mL) and add triethylamine (1.30 g, 12.82 mmol), then pyridine sulfur trioxide complex (1.84 g, 11.55 mmol). Stir at room temperature 3 hours and dilute with 10% ethyl acetate/hexanes (˜150 mL). Wash with water, 1 N aqueous citric acid and saturated aqueous sodium chloride, dry (magnesium sulfate), filter and concentrate to give the desired compound as a white solid.

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