[C:1]([O:5][C:6]([N:8]1[C@@H:12]([CH2:13][CH2:14][C:15]2[CH:20]=[CH:19][C:18](Br)=[CH:17][CH:16]=2)[C@H:11]([CH3:22])[O:10][C:9]1([CH3:24])[CH3:23])=[O:7])([CH3:4])([CH3:3])[CH3:2].[C:25]1([C:31]([C:33]2[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=2)=[NH:32])[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1.CC(C)([O-])C.[Na+]>C1(C)C=CC=CC=1>[C:1]([O:5][C:6]([N:8]1[C@@H:12]([CH2:13][CH2:14][C:15]2[CH:20]=[CH:19][C:18]([N:32]=[C:31]([C:25]3[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=3)[C:33]3[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=3)=[CH:17][CH:16]=2)[C@H:11]([CH3:22])[O:10][C:9]1([CH3:24])[CH3:23])=[O:7])([CH3:4])([CH3:3])[CH3:2]To a solution of (4S,5S)-4-[2-(4-bromo-phenyl)-ethyl]-2,2,5-trimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (3.13 g) in toluene (30 ml) were added diphenylmethanimine (1.71 g) and sodium tert-butoxide (1.06 g). The reaction mixture was degassed by bubbling argon through the mixture for several minutes. BINAP (489 mg) and Pd2(dba)3 (216 mg) were then added and the reaction mixture was stirred at 100° C. for 20 h. The reaction mixture was then cooled to room temperature, poured into EtOAc, and extracted with water. The organic layer was separated, dried over Na2SO4, and concentrated in vacuo. The residue was purified by flash chromatography (silica gel, gradient: 0% to 30% EtOAc in hexane) to afford (4S,5S)-4-{2-[4-(benzhydrylidene-amino)-phenyl]-ethyl}-2,2,5-trimethyl-oxazolidine-3-carboxylic acid tert-butyl ester as a yellow oil (3.2 g, 82%). MS (ISP): 499.3 ([M+H).
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