Cl.[CH3:2][C:3]1([CH3:9])[NH:8][CH2:7][CH2:6][S:5][CH2:4]1.[N:10]([O-])=[O:11].[Na+].C(=O)([O-])[O-].[K+].[K+]>O>[N:10]([N:8]1[CH2:7][CH2:6][S:5][CH2:4][C:3]1([CH3:9])[CH3:2])=[O:11]12 ml of 10N HCl are added with cooling to a mixture of 15.7 g of 3,3-dimethyltetrahydro-1,4-thiazine (step c) and 60 ml of ice-water. A solution of 12.4 g of sodium nitrite in 40 ml of water is then added dropwise at 4° to 6° C. The mixture is subsequently stirred at room temperature for 4 hours, rendered alkaline with potassium carbonate and extracted by shaking with ethyl acetate. The organic phase is dried and concentrated in a water jet vacuum. Yield: 17.5 g; M.p.: yellow oil.
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