[S:1](Cl)(Cl)(=[O:3])=[O:2].[C:6]1([C:12]2[N:13]=[CH:14][S:15][C:16]=2[N:17]2C(=O)C3=CC=CC=C3C2=O)[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1.[NH3:28].NN>ClCCl.CO>[NH2:17][C:16]1[S:15][C:14]([S:1]([NH2:28])(=[O:3])=[O:2])=[N:13][C:12]=1[C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1.[NH2:17][C:16]1[S:15][CH:14]=[N:13][C:12]=1[C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1The crude mixture of sulfonyl chloride with 4-phenyl-5-phthalimido-thiazole (231 mg) in dichloromethane (10 ml) was treated with ammonia in methanol (900 μl, 2.0 M) dropwise at ambient temperature. After 10 min the mixture was concentrated in vacuo. The residue was suspended in ethanol (10 ml), treated with ethanolic hydrazine (660 μl, 1.0 M, 660 μmol) and heated to reflux. After 1.5 hr a further portion of ethanolic hydrazine was added (660 μl, 1.0 M, 660 mol) and reflux continued for 15 hr. The cooled mixture was filtered and concentrated in vacuo. Flash chromatography on silica gel (ethyl acetate/hexanes) yielded pure 5-amino-2-(aminosulfonyl)-4-phenylthiazole (56 mg, 36% for 3 steps) and 5-amino-4-phenylthiazole (17 mg, 16% for 3 steps).
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