[C:1]([N:6]1[CH2:10][CH2:9][O:8][C:7]1=[O:11])(=[O:5])/[CH:2]=[CH:3]/[CH3:4].[NH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.FC(F)(F)S(O)(=O)=O.[Cl-].[NH4+]>C1(C)C=CC=CC=1>[C:13]1([NH:12][CH:3]([CH3:4])[CH2:2][C:1]([N:6]2[CH2:10][CH2:9][O:8][C:7]2=[O:11])=[O:5])[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1
A solution of 3-crotonoyl-1,3-oxazolidin-2-one (47 mg, 0.3 mmol) and Pd((R)-binap)(H2O)2(OTf)2 (8.0 mg, 0.0075 mmol) in toluene (1.5 ml) in a stream of nitrogen was cooled to 0° C., and aniline (42 mg, 0.45 mmol) was added. To the solution was dropwise added trifluoromethanesulfonic acid (63 μL, 0.45 mmol), and the resulting mixture was stirred at room temperature for 24 hours. When no starting material was detected, a saturated aqueous solution of ammonium chloride was added to quench the reaction, and the resulting mixture was extracted with ethyl acetate. The organic layer was concentrated and purified by a silica gel column chromatography (hexane:ethyl acetate=1:1) to give the objective 3-(3-phenylaminobutyryl)-oxazolidin-2-one (66 mg, 89% yield). The enantiomeric excess ratio was determined to be 94%. e.e. by a liquid chromatography with an optical isomer separating column (column: AD-H).
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