C[O:2][C:3]([C:5]1[C:10]2[O:11][CH2:12][C@H:13]([CH2:23][OH:24])[N:14]([C:15]3[CH:20]=[CH:19][C:18]([O:21][CH3:22])=[CH:17][N:16]=3)[C:9]=2[CH:8]=[CH:7][CH:6]=1)=[O:4].[Na+].[Cl-:26]>CO>[ClH:26].[OH:24][CH2:23][C@H:13]1[CH2:12][O:11][C:10]2[C:5]([C:3]([OH:4])=[O:2])=[CH:6][CH:7]=[CH:8][C:9]=2[N:14]1[C:15]1[CH:20]=[CH:19][C:18]([O:21][CH3:22])=[CH:17][N:16]=1To a solution of (S)-methyl-3-(hydroxymethyl)-4-(5-methoxypyridin-2-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine-8-carboxylate 3.6 g (11 mmol) of step 6 in methanol 40 mL was dropwise added 10 mL of 4N NaCl. The reaction mixture was refluxed at 60° C. for 3 hrs with stirring and then cooled to room temperature. Neutralization with 1N HCl 40 mL yielded the title compound as a precipitate. This was filtered, washed with distilled water and concentrated in a vacuum. Product: 2.6 g (yield 75%).
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