[NH2:1][C:2]1[S:3][C:4]2[C:10](=[O:11])[CH2:9][CH:8]([CH3:12])[CH2:7][C:5]=2[N:6]=1.C1CCN2C(=NCCC2)CC1.C1N=[CH:27][N:26]([C:29](N2C=NC=C2)=[O:30])[CH:25]=1.CNC>CC#N>[CH3:25][N:26]([CH3:27])[C:29]([NH:1][C:2]1[S:3][C:4]2[C:10](=[O:11])[CH2:9][CH:8]([CH3:12])[CH2:7][C:5]=2[N:6]=1)=[O:30]
To a solution of 2-amino-5-methyl-5,6-dihydro-4H-benzothiazol-7-one (30.0 g, 0.165 mol) in MeCN (750 mL) are added DBU (75.2 g, 0.495 mol) and CDI (80.1 g, 0.495 mol) at RT. The reaction mixture is stirred at 110° C. overnight. Dimethylamine (93.5 g, 1.15 mol) and another portion of DBU (175 g, 1.15 mol) are added to the mixture at RT and the stirring is continued overnight at 110° C. After cooling to RT, the reaction mixture is evaporated in vacuo and the residue is poured into ice water. The reaction mixture is treated with HCl (6 M) to pH to 5. The aqueous mixture is extracted with EtOAc (3×300 mL). The combined organic phase is washed with brine and dried over anhydrous Na2SO4. The solvent is evaporated and the residue is recrystallized from hexane to give 1,1-dimethyl-3-(5-methyl-7-oxo-4,5,6,7-tetrahydro-benzothiazol-2-yl)-urea (32.1 g, 77% yield).
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