Hydrazine hydrate (1:1) → 4-(3-bromo-5-chlorophenoxy)-5-chloro-1H-indazole

Participants

Reaction Steps

A suspension of 2-(3-bromo-5-chlorophenoxy)-3-chloro-6-fluorobenzaldehyde fluorobenzaldehyde (4.5 kg; 12.36 moles; 1.0 eq.) in DMSO (18 L) was degassed, after which hydrazine monohydrate (6.192 kg; 123.7 moles; 10.0 eqs.) was added over 20 minutes at room temperature. The reaction solution was degassed again, stirred at room temperature for 15 minutes, heated to 73° C., and then aged for 16 hours. After the mixture was cooled to room temperature, isopropanol (15 L) and then water (40 L) were added, and the resulting mixture cooled to room temperature, filtered under pressure, and washed with isopropanol:water (1:2; 10 L), water (12 L), and heptane (12 L). The title product as a solid was obtained after drying at 30° C.-35° C. under vacuum for four days.

Provenance & Evidence