Indazole

Indazole, also called isoindazole, is a heterocyclic aromatic organic compound. This bicyclic compound consists of the fusion of benzene and pyrazole.

Indazole is an amphoteric molecule which can be protonated to an indazolium cation or deprotonated to an indazolate anion. The corresponding pKa values are 1.04 for the equilibrium between indazolium cation and indazole and 13.86 for the equilibrium between indazole and indazolate anion.

Indazole derivatives display a broad variety of biological activities.

Indazoles are rare in nature. The alkaloids nigellicine, nigeglanine, and nigellidine are indazoles. Nigellicine was isolated from the widely distributed plant Nigella sativa L. (black cumin). Nigeglanine was isolated from extracts of Nigella glandulifera.

The Davis–Beirut reaction can generate 2H-indazoles.

Indazole, C7H6N2, was obtained by E. Fischer (Ann. 1883, 221, p. 280) by heating ortho-hydrazine cinnamic acid,

Drugs made from Indazole

Benzydamine, commonly branded as Tantum Verde and Difflam, is the most well known Indazole derivative. It is a nonsteroidal anti-inflammatory, with local anaesthetic and analgesic properties for pain relief and anti-inflammatory treatment of inflammatory conditions of the mouth and throat.

See also

• Indole, an analog with only one nitrogen atom in position 1.
• Benzimidazole, an analog with the nitrogen atoms in positions 1 and 3.
• Simple aromatic rings
• 7-Nitroindazole, an indazole-based nitric oxide synthase inhibitor

• Synthesis: Stadlbauer, W. (2002). "Product Class 2: 1H- and 2H-Indazoles". In Neier; Bellus (eds.). Category 2, Hetarenes and Related Ring Systems. Science of Synthesis. Houben-Weyl. doi:. ISBN 9783131122711.
• Review: Schmidt, Andreas; Beutler, Ariane; Snovydovych, Bohdan (2008). "Recent Advances in the Chemistry of Indazoles". European Journal of Organic Chemistry. 2008 (24): 4073–4095. doi:.