[CH3:1][CH:2]1[C:7](=[O:8])[NH:6][C:5]2[CH:9]=[C:10]([CH2:13][CH2:14][NH2:15])[CH:11]=[CH:12][C:4]=2[O:3]1.[Cl:16][C:17]1[CH:18]=[C:19]([CH:22]=[CH:23][CH:24]=1)[CH:20]=O.[BH4-].[Na+].O>CO.O1CCCC1>[CH3:1][CH:2]1[C:7](=[O:8])[NH:6][C:5]2[CH:9]=[C:10]([CH2:13][CH2:14][NH:15][CH2:20][C:19]3[CH:22]=[CH:23][CH:24]=[C:17]([Cl:16])[CH:18]=3)[CH:11]=[CH:12][C:4]=2[O:3]1
915 mg (4.437 mmol) of 2-methyl-3-oxo-6-(2-amino-ethyl)-3,4-dihydro-2H-1,4-benzoxazine is dissolved in 16 ml of a methanol/tetrahydrofuran mixture (4:1). After adding 623.7 mg (4.437 mmol) of 3-chlorobenzaldehyde, the batch is stirred for two hours at room temperature. Then, 91.1 mg (2.408 mmol) of sodium borohydride is added in portions and stirred for another two hours at room temperature. The batch is added to 50 ml of water, and after three-fold extraction with ethyl acetate, the combined organic extracts are washed with brine, dried and the solvent is spun off. The remaining residue is chromatographed on silica gel (mobile solvent: ethyl acetate/methanol). Yield 584.6 mg (39.8%).
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