How is 4,5,6,7-Tetrahydro-2H-indazol-5-amine dihydrochloride (CAS: 74197-17-4) typically synthesized?

4,5,6,7-Tetrahydro-2H-indazol-5-amine dihydrochloride can be synthesized by the condensation of indole with an appropriate aldehyde or ketone followed by reduction to form the tetrahydroindazole ring. The dihydrochloride salt is then obtained by protonation. Commonly, this synthesis involves the use of a Lewis acid catalyst like aluminium chloride to promote the condensation step, and sodium borohydride for reduction.