[NH2:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[O-]S([O-])(=O)=O.[Na+].[Na+].[CH:15](=O)[CH3:16].[CH2:18]([O:25][C:26](=[O:30])[NH:27][CH:28]=[CH2:29])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1.B(F)(F)F.CCOCC>C(Cl)Cl>[CH2:18]([O:25][C:26](=[O:30])[NH:27][C@H:28]1[C:7]2[C:2](=[CH:3][CH:4]=[CH:5][CH:6]=2)[NH:1][C@@H:15]([CH3:16])[CH2:29]1)[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1Aniline (3.64 mL, 39.97 mmol, 1.0 equ) was dissolved in methylene chloride (100 mL) and Na2SO4 (2 g) was added and cooled to −25° C. Acetaldehyde (2.23 mL, 39.97 mmol, 1.0 equ.) was added to the solution and stirred for 1 h at −25° C. Sodium sulfate was filtered off and N-vinyl-carbamic acid benzyl ester (7.07 g, 39.97 mmol, 1.0 equiv) was added to the filtrate at −25° C., followed by boron triflouride diethyl etherate (0.50 mL, 3.9 mmol, 0.1 equ). The reaction was allowed to stir at −25° C. for 1 h and then warmed to room temperature and stirred for 10 h. The reaction was evaporated in vacuo and the residue was purified by Biotage flash system (20% ethyl acetate/80% hexane) to yield 4.0 g, 33% of (±)-cis-(2-methyl-1,2,3,4-tetrahydro-quinolin-4-yl)-carbamic acid benzyl ester as a white solid.
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