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

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Reaction Conditions

Reaction Steps

Dissolve (2R,5S)-2-(2,2-dimethylpropoxy)-5-hydroxymethylmorpholine-4-carboxylic acid tert-butyl ester (3.67 g, 12.1 mmol) in anyhydrous dimethylsulfoxide (25 mL) and dichloromethane (4 mL) and cool to 0° C. under nitrogen. Add diisopropylethylamine (7.4 mL, 42.3 mmol) then pyridine sulfur trioxide (3.47 g, 21.8 mmol) in 2 portions. Stir at 0° C. for 20 minutes and then remove from the cooling bath to allow all solids to dissolve. Pour into ice cold saturated aqueous sodium chloride, extract with 10% ethyl acetate/hexanes, wash with 0.1 N aqueous citric acid (30 mL), saturated aqueous sodium chloride (30 mL), dry (magnesium sulfate), filter and concentrate to give the desired compound as a colorless oil (3.37 g, 92%).

Provenance & Evidence