Diisopropylethylamine → (2R,5R)-2-(2,2-Dimethylpropoxy)-5-formylmorpholine-4-carboxylic acid tert-butyl ester

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Reaction Steps

Add pyridine sulfur trioxide complex (4.82 g, 30.26 mmol) to (2R,5S)-2-(2,2-dimethylpropoxy)-5-hydroxymethylmorpholine-4-carboxylic acid tert-butyl ester (5.10 g, 16.81 mmol) and N,N-diisopropylethylamine (7.61 g, 58.83 mmol) in dimethylsulfoxide (42 mL) and dichloromethane (8 mL) at −4° C. Stir 20 minutes, pour into ice cold saturated aqueous sodium chloride. Extract with 10% ethyl acetate/hexanes. Wash with 0.1 N aqueous citric-acid and saturated aqueous sodium chloride. Dry (magnesium sulfate), filter and concentrate to give the desired compound of a colorless oil, which is used directly in the next step without further purification (5.02 g).

Provenance & Evidence