Yield:-

Reaction Conditions:

Stage #1: 4-bromo-2-ethylbenzenamine hydrochloridewith hydrogenchloride;trifluoroacetic acid;sodium nitrite in water at 0; for 1 h;
Stage #2: with hydrogenchloride;tin(ll) chloride in water at 0 - 20; for 15 h;

Steps:

27.A

Example 27 8-Bromo-6-ethyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole hydrochloride Step A.; A solution of sodium nitrite (0.70 g, 10.2 mmol) and H₂O (2.1 mL) was added dropwise at 0° C. to a solution of 4-bromo-2-ethylbenzenamine hydrochloride (2.0 g, 8.45 mmol) in 12N HCl (20.1 mL) and TFA (2.6 ml). The reaction mixture was stirred at 0° C. for 1 h followed by the dropwise addition of a solution of tin(II)chloride (3.53 g, 18.6 mmol) in 12N HCl (5.0 mL) and H₂O (0.7 mL) at 0° C. The reaction mixture stirred for 15 h at 20° C. and was filtered to give 1-(4-bromo-2-ethylphenyl)hydrazine hydrochloride as an off-white solid (2.9 g, 11.5 mmol).

References:

US2007/27178,2007,A1 Location in patent:Page/Page column 24