Stannous chloride dihydrate → 3-Chloro-2-(3'-chloropropylthio)phenyl hydrazine

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3-Chloro-2-[(3-chloropropyl)sulfanyl]aniline (4.2 g, 15.4 mmol) was dissolved in TFA (24 mL) at 23° C. With stirring concentrated HCl (24 mL) was added. This mixture was cooled in an ice bath. A solution of NaNO2 (1.17 g, 10 mmol) in water (6 mL) was added dropwise over 10 min. The internal temperature of the reaction was maintained at 21 5° C. during this addition, and then maintained at 0° C. for 1 h at which time it was transferred via cannula over 10 min to a stirred solution (8 mL) of SnCl2.2H2O (7.65 g, 34 mmol) in concentrated HCl cooled in. an ice bath. The cooling bath was then removed and the reaction was allowed to warm to 23° C. for 1 h. It was recooled in an ice bath. Aqueous NaOH solution (50%) was added dropwise until pH>12 affording a heterogeneous product which was treated with CH2Cl2-MeOH (20:1, 250 mL). This mixture was filtered and the resulting two-phase filtrate was extracted with CH2Cl2 (2×200 mL). The combined organic extracts were dried (MgSO4) and concentrated in vacuo. to afford 3-Chloro-2-(3′-chloropropylthio)phenyl hydrazine (4.0 g, 90%) as a brown oil. The resulting oil was dissolved in CH2Cl2 (100 mL),and a stream of HCl gas was bubbled into this solution for 5 min. The resultant purple solid was isolated after evaporation of the solvent to afford 1-{3-chloro-2-[(3-chloropropyl)sulfanyl]phenyl}hydrazine hydrochloride and used without further purification. 1H NMR (CD3OD, 300 MHz) δ7.37 (t, 1H, J=8.0 Hz), 7.15 (dd, 1H, J=8.1, 1.1 Hz), 6.95 (dd, 1H, J=8.5, 1.1 Hz), 3.67 (t, 2H, J=6.3 Hz), 2.95 (t, 2H, J=7.0 Hz), 1.90 (quintet, 2H, J=6.6 Hz) ppm

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