Oxindole Explained

Oxindole (2-indolone) is an aromatic heterocyclic organic compound with the formula C6H4CHC(O)NH. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing ring. Oxindole is a modified indoline with a substituted carbonyl at the second position of the 5-member indoline ring. Classified as a cyclic amide, it is a pale yellow solid.

Formation and reactions

Oxindole is derived in nature from tryptophan, formed by gut bacteria ("normal flora"). It is normally metabolized and detoxified from the body by the liver. In excess, it can cause sedation, muscle weakness, hypotension, and coma. Patients with hepatic encephalopathy have been recorded to have elevated serum oxindole levels.^[1]

Treatment with phosphorus pentasulfide gives the thione.

Oxindoles

thumb|center|Rhynchophylline, a naturally occurring oxindole is a medicinal used as an NMDA antagonist and a calcium channel blocker.^[2] Beyond, the parent compound, oxindoles include many compounds,^[3] for example 3-methyloxindole^[4] and semaxanib.^[5]

Notes and References

1. Riggio. Oliviero. Mannaioni, Guido . Ridola, Lorenzo . Angeloni, Stefania . Merli, Manuela . Carlà, Vincenzo . Salvatori, Filippo Maria . Moroni, Flavio . Peripheral and Splanchnic Indole and Oxindole Levels in Cirrhotic Patients: A Study on the Pathophysiology of Hepatic Encephalopathy. The American Journal of Gastroenterology. 2 February 2010. 105. 6. 1374–1381. 10.1038/ajg.2009.738. 20125128. 20633097.
2. Kang TH, Murakami Y, Matsumoto K, Takayama H, Kitajima M, Aimi N, Watanabe H . Rhynchophylline and Isorhynchophylline Inhibit NMDA Receptors Expressed in Xenopus Oocytes . European Journal of Pharmacology . 2002 . 455 . 1 . 27–34 . 10.1016/S0014-2999(02)02581-5 . 12433591 .
3. 10.1055/s-0029-1216975. Asymmetric Syntheses of Oxindole and Indole Spirocyclic Alkaloid Natural Products . 2009 . Trost . Barry . Brennan . Megan . Synthesis . 2009 . 18 . 3003–3025 .
4. 10.15227/orgsyn.037.0060. Abraham S. Endler and Ernest I. Becker. Org. Synth.. 1957. 37. 60. 3-Methyloxindole.
5. 10.1016/j.tet.2010.03.018 . Tandem Horner–Wadsworth–Emmons/Heck procedures for the preparation of 3-alkenyl-oxindoles: The synthesis of Semaxanib and GW441756 . 2010 . Lubkoll . Jana . Millemaggi . Alessia . Perry . Alexis . Taylor . Richard J.K. . Tetrahedron . 66 . 33 . 6606–6612 .