Proline-catalyzed a-aminoxylation of aldehydes and ketones

Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan 

The direct catalytic enantioselective a-aminoxylation of carbonyl compounds is a synthetically useful method for the preparation of versatile a-hydroxy carbonyl compounds. We have developed the direct catalytic enantioselective a-aminoxyla- 

The reaction was quenched with addition of MeOH (1 mL) and NaBITj (114 mg, 3.0 mmol) and the reaction mixture was stirred for 10 min at room temperature. After addition of pH 7.0 phosphate bufter solution, the organic materials were extracted with ethyl acetate three times and the combined organic extracts were washed with brine, dried over anhydrous Na2S04, and concentrated in vacuo after filtration. 

Note Due to the instability of 2-anilinoxypropanal, it was isolated and characterized after conversion to 2-anilinoxypropanol by reduction with NaBH4. 

Purification by silica gel column chromatography (eluent ethyl acetate hexane = 1 10-1 5) gave (7 )-2-anilinoxypropanol (lOOmg, 0.6mmol) quantitatively. 

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